Effects of finishing rolling temperatures and reduction on the mechanical properties of hot roll

王娜，刘玉叶，刘美玲，等. 响应面优化金丝小枣碱提多糖工艺及其抗氧化活性研究[J]. 食品工业科技，2023，44（7）：163−169. doi:10.13386/j.issn1002-0306.2022060026WANG Na, LIU Yuye, LIU Meiling, et al. Optimization of Alkali Extraction Process of ‘Jinsixiaozao’ Polysaccharide by Response Surface Methodology and Its Antioxidant Activity[J]. Science and Technology of Food Industry, 2023, 44(7): 163−169. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022060026· 工艺技术 ·响应面优化金丝小枣碱提多糖工艺及其抗氧化活性研究王　娜1，刘玉叶1，刘美玲1，刘孟军1,2，赵智慧1,2, *（1.河北农业大学园艺学院，河北保定 071001；2.河北农业大学枣研究中心，河北保定 071001）摘　要：以金丝小枣为原料，通过单因素考察提取温度、时间、料液比和NaOH 浓度对多糖得率的影响，在此基础上进行Box-Behnken 试验来优化碱提多糖的提取工艺，并对其进行总糖含量、扫描电镜、红外光谱及抗氧化活性测定。

结果表明，碱提多糖最佳工艺为：料液比1:35（g/mL ），提取温度80 ℃，提取时间120 min ，NaOH 浓度为0.2 mol/L ，在此条件下多糖的得率为11.44%，总糖含量为69.39%。

扫描电镜表明其具有不规则块状结构，内部紧实；红外光谱表明枣碱提多糖具有C=O 和C-H 等酸性多糖的特征吸收峰。

Wear253(2002)107–113Effects of carbon content on wear property in pearlitic steelsMasaharu Ueda a,∗,Koichi Uchino a,Akira Kobayashi ba Yawata Research and Development Laboratory,Nippon Steel Corporation,1-1Tobihata-cho,Tobata-ku,Kitakyushu804-8501,Japanb Yawata Works,Nippon Steel Corporation,1-1Tobihata-cho,Tobata-ku,Kitakyushu804-8501,JapanAbstractTo clarify the effects of carbon content on the rolling contact wear in steels,the authors conducted a two-cylinder rolling contact wear test using pearlitic steels with a carbon content in a range from0.8to1.0mass%and studied the relationship between the carbon content and the rolling contact wear.In addition,the authors examined the dominating factor in the rolling contact wear in pearlitic steels and the work-hardening rate of the rolling contact surface.The mainfindings obtained are as follows:(1)The wear resistance of pearlitic steels improve as carbon content increases.(2)The dominating factor in the rolling contact wear of pearlitic steels is the rolling contact surface hardness(RCSH).(3)The improved wear resistance of pearlitic steels is attributable to an increase in RCSH due to raising the work-hardening rate of the rolling contact surface as carbon content increases.(4)The reason why the work-hardening rate of the rolling contact surface of pearlitic steel rises as carbon content increases is considered to be as follows:an increase in the cementite density increases the amount of dislocation in the matrix ferrite and promotes the grain refinement of the matrix ferrite.As a result,the matrix ferrite is strengthened through the promotion of dislocation hardening and grain refinement.©2002Elsevier Science B.V.All rights reserved.Keywords:Wear resistance;Rail;Pearlitic steel;Work-hardening;Rolling contact surface hardness(RCSH)1.IntroductionIn recent years,railway companies have been increasing the speed of passenger trains and the load of freight trains to increase the efficiency of rail transport.This trend has been increasing the severity of the environment in which rails are used.Especially on heavy-haul railways in North America,the increasing wear of the railhead and the in-creasing frequency of internal fatigue defects in the railhead on curves have been causing a reduction in rail service life. Consequently,the railway companies have been calling for the development of rails having a longer life.A rail is worn by rolling contact involving slip with the wheel.The mechanism of rail wear is considered to be an adhesive wear,based on the minute shear fracture and plastic deformation of rolling contact surfaces[1,2].Therefore,how to increase the hardness of rail steels as an effective measure for improving the wear resistance of rails has been studied. In conventional rail steels with a pearlite structure,various high-strength rails have been developed by decreasing the ∗Corresponding author.Tel.:+81-93-872-6373;fax:+81-93-872-6809. E-mail address:uedam@yawata.nsc.co.jp(M.Ueda).lamellar spacing of the pearlite structure,thus contributing to a longer rail life on curves[3–5].The rolling contact wear property of rail steels is corre-lated with the hardness,as confirmed in the case of pearlitic steels.On the other hand,it is reported that rolling contact wear property of rail steels can not be evaluated by their hardness alone because the amount of wear greatly varies depending on changes in the microstructure and the carbon content of steels[6–9].However,the reason why rolling contact wear varies depending on these points have not been fully explained.To clarify the effects of carbon content on the rolling con-tact wear in steels,the authors conducted a two-cylinder rolling contact wear test using pearlitic steels with a car-bon content in a range from0.8to1.0mass%,and studied the relationship between the carbon content and the rolling contact wear.In addition,based on a microhardness mea-surement and microstructure observation of rolling contact surfaces,the authors examined the dominating factor in the rolling contact wear in pearlitic steels and the effects of car-bon content on this factor,and discussed the mechanism for the change in the microstructure of the rolling contact sur-face and work-hardening rate of the rolling contact surface.0043-1648/02/$–see front matter©2002Elsevier Science B.V.All rights reserved. PII:S0043-1648(02)00089-3108M.Ueda et al./Wear 253(2002)107–113Table 1Chemical composition ranges and hardness range of test steels.Chemical composition (mass%)Hardness (Hv,98N)C Si Mn P S Cr 0.78–1.010.18–0.520.48–1.01≤0.023≤0.0200.15–0.25294–395A 50kg ingot (1250◦C for 2h)→hot rolling (40t)→slack quench or salt-bath.Finally,newly developed Hyper-Eutectoid steel rails are in-troduced.2.Test methods 2.1.Test steelsThe chemical composition and hardness ranges of the test pearlitic steels are given in Table 1.The test steels had car-bon levels of 0.8,0.9and 1.0mass%,and were changed in hardness in the range from 294to 395Hv by heat treatment.These pearlitic steels are called 0.8,0.9and 1.0mass%C steel,respectively in the following discussion.Each steel was produced by vacuum melting electrolytic iron and al-loy,casting the molten steel into an ingot,and hot rolling ingot into a 40mm thick plate.Before specimen prepara-tion,each steel plate was reheated and either subject to accelerated-cooling or to salt-bath heat treatment to vary the hardness of the pearlite structure and to prevent the forma-tion of a proeutectoid cementite structure.2.2.Rolling contact wear testFig.1shows the dimensions and shapes of rolling con-tact wear test specimens and schematically illustrates a rolling contact wear test machine.A cylinder,measuringFig.1.Dimensions and shapes of wear test specimens and schematic illustration of rolling wear test machine.30mm in diameter and 8mm in thickness,was machined from each steel plate and was used as a test specimen.A cylinder of the same diameter and thickness as mentioned was machined from the 0.8mass%C steel with a hardness of 380Hv and was used as a wheel specimen.The rolling contact wear property of each test specimen was evaluated by a Nishihara wear test machine capable of simulating the rolling contact wear of the rail/wheel.The test condi-tions were set at a maximum Hertzian contact pressure of 640MPa and a slip ratio of 20%to simulate the extreme wearing condition of the railhead side in curved tracks.The rolling contact surface of the specimen was cooled with compressed air to prevent the change of the microstructure by heating and to remove wear debris.The weight loss was determined to be the difference between the pre-test weight and the post-test weight.The number of rolling cycles in this wear test was based on 700,000cycles of the test spec-imen.To evaluate the wear property of the test specimens under rolling cycles,some wear tests were ended after 100,000;300,000;or 500,000cycles.After the test,the hardness of the rolling contact surface was measured with a microhardness tester,and its thin-film microstructure was observed with a transmission electron microscope (TEM).3.Test results3.1.Effect of pre-test hardness on weight lossFig.2shows the relationship between the pre-test hardness and the weight loss of the test specimens.There is almost a linear relationship between the pre-test hardness and the weight ly,the weight loss decreases as the pre-test hardness increases.Moreover,there is a close correlation between the weight loss and the carbon content.3.2.Effect of carbon content on weight lossTo clarify the effect of the carbon content on the weight loss,the relationship between the carbon content and the weight loss was examined.Fig.3shows the relationship be-tween the carbon content and the weight loss of the test specimens in the hardness range of 385–395Hv.There is al-most a linear correlation between the carbon content and the weight ly,the weight loss of the test specimens decreases as the carbon content increases.M.Ueda et al./Wear 253(2002)107–113109Fig.2.Relationship between pre-test hardness and weight loss of test specimens.Thus,it can be seen that the rolling contact wear property of the pearlitic steels greatly depend not only on the pre-test hardness but also on the carbon content.3.3.Effects of number of rolling cycles on weight loss and post-test rolling contact surface hardness (RCSH)It has been reported that the rolling contact wear prop-erty of rail steels is closely correlated with the number of rolling cycles and the post-test rolling contact surface hard-ness (RCSH)[10,11].Accordingly,the authors investigated the relationship between the number of rolling cycles and the weight loss,and the relationship between the number of rolling cycles and the post-test RCSH by using test speci-mens with a pre-test hardness in the range from 385to 395Hv.The relationship between the number of rollingcycles Fig. 3.Relationship between carbon content and weight loss of test specimens with pre-test hardness range from 385to 395Hv.Fig.4.Relationship between number of rolling cycles and weight loss of test specimens with pre-test hardness range from 385to 395Hv.in the range from 100,000to 700,000and the weight loss of the test specimens is shown in Fig.4.The relationship between the number of rolling cycles in the same range as mentioned and the post-test RCSH of the test specimens is shown in Fig.5.There is little difference in weight loss in all of the test specimens up to 100,000cycles.As the number of rolling cy-cles exceed 100,000,the weight loss changes in accordance with the carbon content,and an increase in the weight loss of the test specimens with a high carbon content is suppressed.As the number of rolling cycles increase further,the test specimens with a high carbon content have less weight loss compared with the test specimens with a low carbon content.The post-test RCSH in all the test specimens increase as the number of rolling cycles increase up to 100,000.As the number of rolling cycles exceed 100,000,thepost-testFig.5.Relationship between number of rolling cycles and post-test rolling contact surface hardness of test specimens with pre-test hardness range from 385to 395Hv.110M.Ueda et al./Wear 253(2002)107–113Fig.6.TEM images beneath rolling contact surface of test specimens and selected area diffraction patterns after 700,000cycles:(a)bright-field image of 0.8mass%C steel;(b)dark-field image of 0.8mass%C steel;(c)bright-field image of 1.0mass%C steel;(d)dark-field image of 1.0mass%C steel.RCSH changes in accordance with the carbon content,and an increase in the post-test RCSH of the test specimens with a high carbon content is promoted.As the number of rolling cycles increase further,the post-test RCSH of the test spec-imens with a high carbon content is higher than that of the test specimens with a low carbon content.When the number of rolling cycles is 700,000,the post-test RCSH increases to 670Hv for the 0.8mass%C steel,to 710Hv for the 0.9mass%C steel,and to 750Hv for the 1.0mass%C steel.3.4.Observation of microstructure beneath rolling contact surfaceFig.6shows TEM images beneath the rolling contact sur-face of the test specimens of the 0.8and 1.0mass%C steel after 700,000cycles and the diffraction patterns obtained from a selected area of 1mm in diameter.In the bright field images,the fracturing in the cementite phase,dislocations,and some dislocation cells are observed in the matrix ferrite in each test specimen.In the diffraction patterns of the pho-tographed regions,diffraction spots of the cementite phase and the ferrite phase are dispersed,and the diffraction spots of the ferrite phase are formed in rings in each test specimen.This means that there are a lot of crystalline grains which are thought to be subgrains or nanocrystalline grains withinthe small area.Upon considering the difference between the carbon content and the size of crystalline grains in the dark field images,it is noted that the size of crystalline grains of the test specimen with a high carbon content is smaller than that of the test specimen with a low carbon content.This means that the matrix ferrite in the rolling contact surface is refined due to the increased carbon content of the pearlitic steels.4.DiscussionsThese test results showed that the change in the weight loss is closely correlated with the RCSH and that the RCSH depends on the number of rolling cycles in the wear test and the carbon content of the test specimens.In this chap-ter,the authors quantify the relationship between the RCSH and weight loss,and clarify the dominating factor in the rolling contact wear in pearlitic steels and the effects of car-bon content on this factor.Further,the authors discuss the mechanism whereby the microstructure beneath the rolling contact surface varies as carbon content increases and the work-hardening rate of the rolling contact surface from the wear test results and the observation results of rolling contact surfaces.M.Ueda et al./Wear253(2002)107–113111Fig.7.Relationship between average rolling contact surface hardness and wear rate of test specimens at200,000cycle intervals between100,000 and700,000cycles.4.1.Dominating factor in rolling contact wear in pearlitic steels and effects of carbon content on this factorTo clarify the relationship between the RCSH and the weight loss,the authors examined the relationship between the average RCSH and the wear rate in a range of rolling cycles where the RCSH and the weight loss clearly dif-fered in accordance with the carbon content.Fig.7shows the relationship between the average RCSH and the wear rate( W)of test specimens at200,000cycle intervals be-tween100,000and700,000cycles.There is almost a lin-ear relationship between the average RCSH and the wear rate,and the carbon content is not a factor ly, the weight loss of pearlitic steel decreases as the RCSH increases.To confirm the effect of the carbon content on the RCSH, the authors,noting the difference between the pre-and post-test RCSH,set the ratio of the increase in the post-test RCSH to the pre-test hardness.The authors referred to this as the work-hardening rate of the rolling contact surface shown by Eq.(1),and examined the relationship between the carbon content and the work-hardening rate of the rolling contact surface.Fig.8shows the relationship be-tween the carbon content of the test specimens and the work-hardening rate of the rolling contact surface.There is a little change in the work-hardening rate of the rolling contact surface at100,000cycles,at which the RCSH does not change as carbon content increases.However,there is a close relationship between the carbon content and the work-hardening rate of the rolling contact surface at 700,000cycles,at which the RCSH rises as carbon content increases.That is,the work-hardening rate of the rolling contact surface rises as the carbon content increases aftera Fig.8.Relationship between carbon content and work-hardening rate of rolling contact surface of test specimens.period of rolling contact.Work-hardening rate of rolling contact surface(%) =(post-test RCSH−pre-test hardness)(pre-test hardness)×100(1)where the hardness values are all expressed in Vickers hard-ness(Hv).From these results,it is concluded that the dominating factor in the rolling contact wear of pearlitic steels is the RCSH and that the increase in the RCSH depends on the rise in the work-hardening rate of the rolling contact surface as the carbon content ly,it is thought that the improved wear resistance of pearlitic steels is attributable to an increase in RCSH due to raising the work-hardening rate of the rolling contact surface as the carbon content increases.4.2.Mechanism for change in microstructure beneath rolling contact surface and rise in work-hardening rate of rolling contact surface with increase in carbon contentAccording to these test results and observations,the reason why the work-hardening rate of the rolling contact surface of pearlitic steels rises is considered to be as fol-lows:The rolling contact introduces strain into the ferrite phase and at the same time produces minute fractures in the cementite phase beneath the rolling contact surface.Re-peated rolling contact concentrates strain in the ferrite phase that is lower in hardness than the fractured cementite.The strain concentration forms many dislocations in the matrix ferrite,and promotes dislocation hardening and grain refine-ment in the matrix ferrite.As a result,the matrix ferrite is strengthened by dislocation hardening and grain refinement. Moreover,the mechanism whereby the work-hardening rate of the rolling contact surface rises as the carbon content of the pearlitic steels increases is explained as follows:The112M.Ueda et al./Wear 253(2002)107–113increase in the carbon content of the pearlitic steels raises the density of the hard cementite phase.The increase in the cementite density promotes the concentration of strain in the matrix ferrite,and accelerates the grain refinement in the matrix ferrite.As a result,the matrix ferrite is strengthened further through the promotion of dislocation hardening and grain refinement as the carbon content increases.Tarui et al.reported that when a high carbon wire is cold-drawn,the cementite phase in the pearlite structure is decomposed,and the carbon of the cementite phase is dis-solved into the matrix ferrite phase,and the ferrite phase is strengthened by the solid solution of carbon [12].The rolling contact surface is subject to a more severe processing condition than that of the wire drawing,and the cementite phase is presumed to be decomposed by the rolling contact.Therefore,the increased amount of carbon dissolving into the matrix ferrite as the cementite density increases is con-sidered to be one of the factors responsible for the raised work-hardening rate of the rolling contact surface.5.Status of trial rails installationBased on the results of the laboratory test described,it was confirmed that the wear resistance in pearlitic steels could be improved by increasing the carbon content of these steels.To confirm the properties of rails in actual use,therefore,pearlitic steel rails with a carbon content of 0.9mass%and hardness of HB 370were produced on a trial basis and installed in actual tracks.In this chapter,one example of the wear property of these pearlitic steel rails on heavy-haul tracks in North America is described.The new rails were tested in an actual track and compared with the conventional pearlitic steel rails with a carbon con-tent of 0.8mass%and hardness of HB 370(called DHH370).Fig.9shows the relationship between the passingtonnageFig.9.Relationship between passing tonnage and amount of head side wear of rails in a curved track.and the amount of head side wear of these rails in a curved track having a 290m radius.As for the new rail,the amount of head side wear was less than that of the DHH370rail in every passing tonnage.It was confirmed that the wear re-sistance was improved by increasing the carbon content of the pearlitic steels in the actual track.Moreover,when the service life of the new rail was compared with the DHH370rail in half inches in the head side wear,it was clear that the service life of the new rail had been improved by about 55%.Upon confirming the improvement of the service life in actual tracks,the authors developed the Hyper-Eutectoid steel rails (named HE370,HE400)with the carbon content of 0.9mass%and hardness of HB 370and HB 400.It is thought that these rails will contribute in the future to greatly improving the service life of rails in heavy-haul railways where excellent wear resistance is demanded.6.ConclusionsPearlitic steels with different carbon contents were two-cylinder wear tested to study the effect of the carbon content on the rolling contact wear.The dominating factor in the rolling contact wear in pearlitic steels and the effects of carbon content on this factor were examined.Further,the mechanism for the change in the microstructure beneath the rolling contact surface and the rise in the work-hardening rate of the rolling contact surface as the carbon content increases were discussed.The main findings obtained are as follows:(1)The wear resistance of pearlitic steels improve as thecarbon content increases.(2)The dominating factor in the rolling contact wear ofpearlitic steels is the RCSH.That is,the wear resistance of pearlitic steels improves as the RCSH increases.(3)The increase in the RCSH depends on the rise in thework-hardening rate of the rolling contact surface as the carbon content increases.(4)The improving wear resistance of pearlitic steels is at-tributable to an increase in the RCSH due to raising the work-hardening rate of the rolling contact surface as the carbon content increases.(5)The reason why the work-hardening rate of the rollingcontact surface of pearlitic steel rises as the carbon con-tent increases is considered to be as follows:an increase in the cementite density increases the amount of dislo-cation in the matrix ferrite and promotes the grain re-finement of the matrix ferrite.As a result,the matrix ferrite is strengthened through the promotion of dislo-cation hardening and grain refinement.(6)Newly developed Hyper-Eutectoid steel rails (HE370)with a carbon content of 0.9mass%show an improve-ment in service life of about 55%as compared with the conventional pearlitic steel rail (DHH370)with a carbon content of 0.8mass%in an actual track.M.Ueda et al./Wear253(2002)107–113113AcknowledgementsThe authors wish to thank Union Pacific Railroad and Burlington Northern Santa Fe for permitting the actual track tests to be conducted and Dr.Senuma for the fruitful dis-cussions with him and his helpful comments. References[1]G.A.Tomlinson,Philos.Mag.7(1927)905–911.[2]M.Ishida,Shinsenro49(1995)38–40.[3]H.Masumoto,K.Sugino,H.Hayashida,in:Proceedings of theConference on First International Heavy Haul Railway,IHHA, Session212,Colorado Springs,1978.[4]K.Sugino,H.Kageyama,H.Masumoto,in:Proceedings of theConference on Second International Heavy Haul Railway,IHHA, Perth,1982,pp.187–197.[5]K.Sugino,H.Kageyama, C.Urashima,in:Proceedings of the32nd Mechanical Working and Steel,ISS,Warrendale,1990, 171–176.[6]P.Clayton,N.Jin,Wear200(1996)74–82.[7]H.Yokoyama,S.Yamamoto,M.Fujikake,Y.Yoshida,in:Proceedings of the Fourth International Symposium on Rail Steels, ISS,Warrendale,1997,pp.1023–1028.[8]M.Ueda,K.Uchino,H.Kageyama,K.Kutaragi,K.Babazono,in:Proceedings of the Conference on Sixth International Heavy Haul Railway,IHHA,Cape Town,1997,pp.355–369.[9]M.Ueda,K.Uchino,H.Kageyama,M.Kaneta,A.Kobayashi,in:Proceedings of the Conference on IHHA’99STS,V ol.1,IHHA, Moscow,1999,pp.259–266.[10]K.Sugino,H.Masumoto,S.Nishida,C.Urashima,H.Kageyama,M.Hattori,Seitetsukenkyu303(1980)23–38.[11]W.R.Tyfour,J.H.Beynon, A.Kupoor,Wear180(1995)79–89.[12]K.Tarui,N.Maruyama,G.Shigesato,H.Tashiro,Zairyou-to-Process11(1998)1327.。

Chapter 14 Forging of Metals（金属的锻造/锻压）•14.1 Introduction•14.2 Open-Die Forging•14.3 Impression-Die and Closed-Die Forging•14.4 Related Forging Operations•14.5 Rotary Swaging•14.6 Forging-Die Design•14.7 Die Materials and Lubrication•14.8 Forgeability•14.9 Forging Machines•14.10 Forging Practice and Process Capabilities •14.11 Die Manufacturing Methods; Die Failures •14.12 The Economics of Forging14.1 Introduction•Forging（锻造/锻压）–A workpiece is shaped (formed) by compressive forces applied through various dies（模具）and tools（工具）.•one of the oldest metal working processes –4000bc •trationally be performed with a hammer（锤）and anvil（砧/平砧）•mostly require a set of dies and such equipment as a press（压力机）or a forging hammer（锤锻机）.•Typical forged products:–bolts （螺栓）–rivets （铆钉）–connecting rods （连杆）–gears （齿轮）–shaft （轴）–hand tool （手工具）–structural components （结构组件）discrete partsForging （锻件）(a)Source : Forging Industry Association.预锻件终锻件近净形/近成品形状净形/最终形状锻造齿净形挤出花键净形bevel gear （伞齿轮）ForgingFigure 14.1 (b) Landing-gear（起落架/着陆装置）components for the C5A and C5B transport aircraft, made by forging. Source: Wyman-Gordon Company.typical forged partsFigure 14.1 (c) general view of a 445 MN (50,000 ton) hydraulic press. Source: Wyman-Gordon Company.Hydraulic Press （液压机）Forging Process （锻压/锻造工艺）Forging Process-2锻造在制坯中的应用•一般机器或机械上的金属零件的传统生产过程是：冶炼——制坯——切削加工——热处理。

李欣，华建新，罗杰洪，等. 不同提取方法对井冈蜜柚皮精油组成与性质的影响[J]. 食品工业科技，2024，45（3）：83−97. doi:10.13386/j.issn1002-0306.2023030289LI Xin, HUA Jianxin, LUO Jiehong, et al. Effects of Different Extraction Methods on the Composition and Properties of Jinggang Pomelo Peel Essential Oil[J]. Science and Technology of Food Industry, 2024, 45(3): 83−97. (in Chinese with English abstract). doi:10.13386/j.issn1002-0306.2023030289· 研究与探讨 ·不同提取方法对井冈蜜柚皮精油组成与性质的影响李　欣1，华建新1，罗杰洪1，王国庆2，陈　赣2，周爱梅1,*（1.华南农业大学食品学院，广东省功能食品活性重点实验室，广东广州 510642；2.吉安井冈农业生物科技有限公司，江西吉安 343016）摘　要：以井冈蜜柚皮精油（Jinggang pomelo peel essential oil ，JPPEO ）为研究对象，采用水蒸气蒸馏法、低温连续相变法两种方法进行提取，以精油得率为主要指标，研究了萃取温度、压力、时间等因素对井冈蜜柚皮精油得率的影响，并通过正交法进行低温连续相变法提取工艺优化，同时对精油的理化性质及化学组成进行分析。

研究表明，低温连续相变提取井冈蜜柚皮精油（Low-temperature continuous phase transition extraction essential oil ，L-JPPEO ）的最佳工艺为：颗粒度30目，萃取温度55 ℃，萃取压力0.6 MPa ，萃取时间60 min ，解析温度70 ℃，此时精油得率为10.99‰，比水蒸气蒸馏法提取的精油（Hydro distillation essential oil ，H-JPPEO ）得率高出了2.88倍；理化性质实验结果表明，低温连续相变萃取的井冈蜜柚皮精油的不饱和脂肪酸含量较高，游离脂肪酸含量较低，酯类成分含量较低；傅里叶衰减全反射中红外光谱法（Fourier transform infrared spectroscopy ，FTIR ）鉴定出L-JPPEO 和H-JPPEO 含萜烯类化合物、醇类、酚类、醛类以及含羰基化合物。

unit1all polymers are built up from bonding together a single kind of repeating unit. At the other extreme ,protein molecules are polyamides in which n amino acide repeat units are bonded together. Although we might still call n the degree of polymerization in this case, it is less usefull,since an amino acid unit might be any one of some 20-odd molecules that are found in proteins. In this case the molecular weight itself,rather than the degree of the polymerization ,is generally used to describe the molecule. When the actual content of individual amino acids is known,it is their sequence that is of special interest to biochemists and molecular biologists.并不是所有的聚合物都是由一个重复单元链接在一起而形成的。

在另一个极端的情形中，蛋白质分子是由n个氨基酸重复单元链接在一起形成的聚酰胺。

尽管在这个例子中，我们也许仍然把n称为聚合度，但是没有意义，因为一个氨基酸单元也许是在蛋白质中找到的20多个分子中的任意一个。

在这种情况下，一般是分子量本身而不是聚合度被用来描述这个分子。

润滑油专用名词英语和润滑油英语词汇工业润滑油Industry Lubricants水容性加工液与清洗剂Soluble Oil & Cleaner 液压油Hydraulic OIls压缩机油Compressor Oils油性加工油Metal Woking Oils齿轮油Gear Oils涡轮机油Turbine Oils防锈油Rust Preventives纺织机油Textile Knitting Oils热媒油Heat Transfer Oils冷冻机油Refrigerator Oils淬火油Quenching Oils绝缘油Electrical Oils高温链条油Chain Lubricants放电加工油Dielectric Oils镜片研磨液Lens Grinding Coolant导轨油Slideway高品质气缸油High Quality Cylinder Lubricants水箱精Coolant Booster刹车油Break Fluid自动变速箱油Automatic Transmission Fluid齿轮油Gear Oil太空磁铀油精Oil Treatment柴油引擎用油Synthetic Diesel Engine Oil汽车引擎用油Synthetic Motor Oil全天候四行程机油All Seasons 4T Synthetic Motor Oil 摩托车专用齿轮油Motor Cycle Gear Oil农机用油Multi Purpose Tractor Oil复合高温锂基润滑油High Temperature Lithium Complex Grease车用多效润滑脂Auto Grease超强喷合油Low Smoke Engline Oil常见润滑油名词中英文对照:naphthenic base crude 环烷基原油 mixed base crude 混合基原油sour crude 含硫原油feedstock oil 原料油natural gas 天然气refinery gas 炼厂气distillate 馏分lubricating oil distillate 润滑油馏分bottoms(residue) 渣油neutral oil 中性油additive 添加剂multipurpose additive 多效添加剂thickener 增稠剂viscosity index improver 粘指剂pour-point depressant 降凝剂inhibiter 抑制剂detergent additives 清净剂dispersant additives 分散剂ashless additive 无灰添加剂antirust additive(or rust preventive additive or rust inhibiter) 防锈剂extreme-pressure additive 极压剂antiwear additive 抗磨剂oilness additive 油性添加剂anti-oxidant(or oxidation inhibiter) 抗氧剂antifoam additive 抗泡剂emulsifying agent 乳化剂anticorrosion additive 抗氧抗腐添加剂Acid Number(AN) Milligrams Of KOH requirdd in tests tO neutralize all the acidic constituents present in a lg sample Of a petroleum product．Also formally called the Neutralization Number，this property is often used tO indicate the extent ofcon-tamination or oxidation Of used oils.酸值(AN) 也称中和值，指中和1克油品试样中所有酸性物质所需氢氧化钾的毫克数。

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system加入系统tint (to)调色etch (to)蚀刻pickle (to)泡bill (to)开帐单给…debit (to)借encumber (to)障碍illumination照明lamp bracket车灯架degree of illumination照明强度exposure暴露ventilation system通风系统wet (to)加湿wetting变湿wetting power润湿力problems问题wetting defects润湿力缺陷gas气体dividends made payable可分配的股息reporting system通报系统grids格子professional association专业协会proximity measurement仔细测量procurement获得employment雇佣job工作work工作capacity variances容量变化coat (to)给。

The effects of rolling and sensitization treatments on the stress corrosion cracking of 304L stainless steel in salt-spray environmentW.J.Li a ,M.C.Young b ,i b ,W.Kai a ,L.W.Tsay a ,⇑a Institute of Materials Engineering,National Taiwan Ocean University,Keelung 202,Taiwan,ROCbInstitute of Nuclear Energy Research,Division of Nuclear Fuels and Materials,Lungtan,Taoyuan 325,Taiwan,ROCa r t i c l e i n f o Article history:Received 28June 2012Accepted 27October 2012Available online 23November 2012Keywords:A.Stainless steel C.Stress corrosionC.Hydrogen embrittlementa b s t r a c tU-bent and notched tensile tests in a 80°C salt-spray environment were conducted to evaluate the effect of cold rolling at room temperature (CR),warm rolling at 150°C (WR),and a sensitization at 650°C/10h (CRS and WRS)on the hydrogen embrittlement (HE)susceptibility of the 304L stainless steel.The CR specimen exhibited the highest crack growth rate with a greater number of short cracks found in the CRS specimen in U-bent tests.The CR specimen was resistant to HE in notched tensile tests relative to other specimens.Cracking in these specimens was more likely to initiate at the slip bands.Ó2012Elsevier Ltd.All rights reserved.1.IntroductionAISI 304L stainless steel (SS)is used for building dry storage canister for the spent fuel produced in nuclear power plants.In Asian countries,the interim storage canisters are planned to be lo-cated near the coastline,thus,the canister will face the problems of corrosion/stress corrosion in the saline atmosphere with a maxi-mum surface temperature below 180°C.Machining,rolling and multiple-pass welding of the SS plates are unavoidable during the manufacture of canisters.However,these processes impose thermal cycles and/or induce high stress/strain on the materials.Unstable austenitic SSs,such as AISI 304and 316,are known to un-dergo a martensitic transformation during straining.The induced martensite in unstable austenitic SSs is susceptible to hydrogen embrittlement (HE)and/or hydrogen-induced cracking under sta-tic tension [1–4].In a boiling MgCl 2solution at 143°C,the suscep-tibility to stress corrosion cracking (SCC)of hydrogen-charged 304SS increases with an increase in the amount of hydrogen-induced martensite by slow strain rate tests [5].Both SCC and HE are responsible for the environment-induced cracking of 304and 316SSs in boiling MgCl 2solutions [6,7].The mechanism by which the cracking occurs strongly depends on the test temperature.For example,SCC is the dominant mechanism for the cracking of 304SS above 143°C,while HE prevails at the lower temperatures and high loads [6,7].Transgranular SCC is the results of synergistic effects between the corrosion process at the crack tip and slip steps of the specimens [8].Moreover,intergranular HE of 304and 316SSs is caused by the formation of a 0-martensite and dislocation pile-up at austenite grain boundaries [9].Cold-rolled 304specimens (20%reduction in thickness)exhibit not only higher strength but also better HE or SCC resistance than the solution-treated specimen [10–13].The cold-worked 316L specimen has a longer reverse-bending life than the annealed spec-imen after hydrogen charging [14].Improved HE resistance is re-ported to be associated with an increase in the fraction and stability of e -martensite in modified austenitic SSs [15,16].It has been reported that the rolling temperature affects the SCC resis-tance of 304SS [17].In crevice bent-beam tests in 288°C water for 500h,304SS specimens rolled at 150–200°C demonstrate much better SCC resistance than those rolled at 25°C [17].More-over,the surface-machined 304L SS is reported to be susceptible to SCC in 1M HCl at room temperature by U-bent tests,as com-pared with the solution-annealed and cold worked specimens [18,19].It is well known that sensitization not only reduces the resis-tance to grain boundary corrosion,but also increases the HE susceptibility of austenitic SSs [20–22].The influence of sensitiza-tion in austenitic SSs becomes more severe after cold deformation [23].For instance,a sensitized 304L SS suffers from intergranular SCC in a boiling water reactor-simulated environment [24].In re-cent studies,both the sensitized and un-sensitized austenitic SSs show intergranular SCC in a boiling saturated MgCl 2solution [6–10,25,26].However,studies on the simultaneous effects of rolling temperature and sensitization treatment on the HE and/or SCC behavior of 304L SS are still lack of study.In this work,both slow extension rate tensile and U-bent immersion tests were conducted to evaluate the effects of the rolling temperature at 25and 150°C0010-938X/$-see front matter Ó2012Elsevier Ltd.All rights reserved./10.1016/j.corsci.2012.10.027Corresponding author.Tel.:+886224622192x6410;fax:+886224625324.E-mail address:b0186@.tw (L.W.Tsay).and sensitization treatment on the HE susceptibility of304L SS in a salt-spray environment.The fracture appearance of various specimens was examined,with attention paid to the regions show-ing the changes in fracture modes.The relationship between the crack path,fracture features,and cracking susceptibility of rolled specimens was also evaluated.2.ExperimentalThe chemical composition of AISI304L employed in this study by weight percent was18.20Cr,8.04Ni,0.019C,1.53Mn,0.50 Si,0.030P,0.003S,0.40Cu and balanced Fe.The as-received plate (6mm thick)in the solution-annealed condition was designated as the SA specimen.Unidirectional rolling was applied for the thick-ness reduction of the specimens in this work.The SA specimen was rolled to thefinal thickness of4.8mm(a20%reduction in thickness)at25and150°C;the corresponding specimens were named as the CR(cold-rolled)and WR(warm-rolled)specimens, respectively.To evaluate the influence of grain boundary precipi-tates on the HE susceptibility for a given specimen,a sensitization treatment at650°C for10h was performed.For sensitized speci-mens,the suffix‘‘S’’was added to the specimen designation.For example,the designated CRS indicated that the CR specimen underwent a650°C/10h sensitization treatment.Fig.1is a schematic diagram showing the test specimen sec-specimens for each testing condition.The percentage loss of NTS of various specimens was expressed as follows:NTS lossð%Þ¼½NTSðin airÞÀNTSðin saltÞ =NTSðin airÞÂ100%ð1ÞThe U-bent specimen was tested in the same salt-spray condi-tion as the notched tensile specimen.The U-bent specimen with dimensions of120mm(L)Â10mm(W)Â2mm(T)was wire-cut from the surface of the rolled plate.The augmented strain(e) generated at the outer surface of the bent specimen was calculated according to the following equation:eð%Þ¼ðt=2RÞÂ100%ð2Þwhere t is the sample thickness and R is the radius of the die block. Samples with a10%augmented strain were imposed using a die block of10mm in radius.Fig.1(b)shows the configuration of U-bent specimen used in this work.Before bending,the surfaces of the U-bent specimen were ground with2000#abrasive paper. The outer surface of the U-bent specimen is in a tensile stress state, while,the inner surface is in a compressive stress state.To facilitate the initiation and inspection of crack growth during the U-bent test, a hole with a diameter of 1.55mm was drilled through the specimen using an electro-discharged machine.For the crack observations,the U-bent specimens were taken out of the salt-spray chamber periodically then washed carefully with water.Outer surface cracks were inspected by a stereo-microscope at magnifica-tions from15toÀ60X if cracks were present.Only surface cracks were inspected for the comparison of cracking susceptibility of the specimens.The content of strain-induced a0-martensite in various specimens was determined by a Ferritescope which measures the volume fraction of strained-induced a0-martensite [27].The fractured specimens were examined using a Hitachi S4100scanning electron microscope(SEM),with an emphasis on the region showing the changes in the fracture appearance.More-over,electron backscatter diffraction(EBSD)was used to locate the sites of a0(bcc)martensite or e(hcp)martensite formed in the specimens.The crack growth path of the specimens was related with the location of induced martensite.3.Results3.1.Microhardness and microstructuresFig.2shows the optical microstructures of the specimens.The surface hardness and ferrite content of the specimens are listed in Table1.The microstructures of the SA specimen with a hardness of HV163revealed equaxial grains with twins inside the austenite matrix.Rolling introduced slip bands into the specimen and increased the hardness,whereas,the sensitization treatment re-sulted in reverse effects.The CR specimen consisted of denser intersecting slip bands(Fig.2(a))and higher hardness(HV345) relative to other specimens.Moreover,warm rolling led to a less degree of strain-hardening as compared to the room-temperature rolling.The WR specimen(Fig.2(b))with the hardness of HV311 revealed a lower density of slip bands than the CR specimen.After sensitization treatment,reduced slip band density in the CRS specimen(Fig.2(c))led to a decrease in hardness to HV283,as compared with the CR specimen.Further,the WRS specimen exhibited sparser slip bands(Fig.2(d))and moderate strain-hardening(HV273).As shown in previous studies,a0-martensite is more likely to be found at the intersection of two variants of e-martensite[13],and the considerable retransformation of martensites to austenite occurs after sensitization.This results in a lowering of the hardness of the sensitized specimens.The ferrite content of the CR specimen was about9.1%but decreased to2.5%1.A schematic diagram showing(a)the notched tensile and U-bent specimenssectioned from the rolled plate and(b)the configuration of the U-bent specimen.Note that RD is the rolling direction of the plate.26W.J.Li et al./Corrosion Science68(2013)25–33was found that the WR and WRS specimensamount of a0-martensite,0.36and0.33,certain amount of e-martensite could berolled specimens[28].It was clear the transfor-a0-martensite was suppressed during rollingthe higher degree of strain-hardening while temperature could be partly attributed to the for--martensite in the specimen,as compared to that of 3.2.Notched tensile testsFig.3shows the NTS values of various specimens tested in air and the salt-spray environment at80°C.The NTS loss was used as an index to reveal the influence of the harsh environment on the degradation of notched tensile strength.The results indicated the NTS of the CR specimen was the highest,whereas,the SA was the lowest among the tested specimens,regardless of testing conditions.Less strain-hardening of warm rolling also reflected the fact of a lower NTS in the warm-rolled specimens relative to the cold-rolled.Furthermore,sensitization treatment resulted in softening and a decrease in the NTS of the specimen,in comparison with the un-sensitized specimens.In the salt-spray environment, all the specimens suffered from SCC to varying degrees.The SA specimen was most susceptible to SCC,having a NTS loss as high as26%.Clearly,the as-rolled(CR and WR)specimens had much lower NTS loss than the SA and sensitized(CRS and WRS)speci-mens.This result is consistent with those reported in open litera-tures[10–13]indicating that a suitable amount of cold work reduces the HE or SCC susceptibility of304SS.Moreover,the sensitization treatment inevitably increased the SCC susceptibility of the specimens(14–16%for the CRS and WRS specimens)with respect to the un-sensitized specimens(11–9%for the CR and WR specimens).3.3.U-bent tests in salt-spray environmentFig.4shows the typical surface features of the U-bent speci-mens after salt-spray tests.With the ground surface,hairline scratches were left on the specimen before testing.However,these scratches disappeared and showed a moderately rough shiny sur-face after the salt-spray test.This implied the dissolution of top surface material in salt-spray environment,which accompanied with hydrogen absorption at the crack tip[29].In contrast to prior tests in H2S solution[28],corrosion pits were less likely to be found in the salt-spray condition.Fig.5shows the variation in crack length of the U-bent specimens vs.testing period in salt-spray environment.The results showed no crack over the testing interval indicating the SA and WR specimens were more resistant to SCC than other specimens.After85h of testing,afine crack,2.08mm in length wasfirst seen in the CR specimen(Fig.5(a)).The crack grew to a length of about2.79mm after99h in the salt-spray test,Fig.2.Optical micrographs showing the microstructures of the(a)CR,(b)WR,(c)CRS and(d)the WRS specimens.ferrite content of the specimens.SA CR CRS WR WRS1633452833112730.319.10 2.500.360.33Fig.3.The NTS values of various specimens tested in air and salt-spray environ-ment.Note that the percentages indicate the NTS losses in the salt-sprayenvironment.then,showed little change in crack length with increasing time. The cease in the crack growth could be related to strain relaxation after extensive cracking in the CR specimen.Regarding the incuba-tion time,it was longer for the WRS specimen than the CRS.This meant even in the sensitized condition the warm-rolled specimen was less susceptible to cracking than the cold-rolled specimen. Fig.5(b)shows the SCC susceptibility of distinct specimens ranked by using the total crack length.Although two different indexes were applied,the trend of SCC susceptibility of the specimens was similar.It is worth mentioning that the SCC susceptibility of the CRS specimen was equivalent to that of the CR specimen as evaluated by total crack length.The total crack length of the CRS specimen was even longer than that of the CR specimen at thefinal stage of the salt-spray test.The appearance of many short,fine cracks in the CRS specimen resulted in the increased SCC susceptibility.3.4.Fractographic examinations of notched tensile specimenThe macroscopic fracture appearance of the notched tensile specimens is displayed in Fig.6.The SA specimen revealed an obvi-ous reduction in thickness after testing in air.Even in the salt-spray environment,the SA specimen also showed a high reduction in thickness but with small facet regions ahead of notch front (Fig.6(a)).For the CR and CRS specimens tested in air,a lesser reduction in thickness revealed a decreased ductility of the specimens(Fig.6(b))in comparison with the SA specimen.For the case of testing in salt-spray environment,the CR(Fig.6(c)) and CRS(Fig.6(d))specimens exhibited an enlargedflat fracture region and much rougher fracture surface relative to the same specimen tested in air.It was noticed that secondary cracks were easily found on the fracture and lateral surfaces of the CRS speci-men,as shown in Fig.6(d).For the WR and WRS specimens tested in air,the improved ductility,which was associated with the re-duced strain-hardening,resulted in an increase in the shear frac-ture region as compared to the CR and CRS specimens, respectively.While testing in the salt-spray environment,the WR specimen still displayed a moderate reduction in thickness but was characterized by lamellar separations with deep secondary cracks in theflat fracture region(Fig.6(e)).Similar to the CRS spec-imen tested in the salt-sprayed condition,the relatively high NTS loss of the WRS specimen was related to a wide brittle fracture re-gime(Fig.6(f)).The detailed fracture appearance of various notched tensile specimens after testing is shown in Fig.7.For the specimens tested in air,fine dimples were seen in the SA specimen.In addition,the fracture appearance of the CR and CRS specimens was similar, which consisted offine dimples and inter-dispersed facet separa-tions(Fig.7(a)).For the WR and WRS specimens tested in air,par-allel tear ditches and dimples oriented in the crack growth direction were observed(Fig.7(b)).The variations in fracture features could be associated with the degree of strain-hardening or reduced ductility between the cold-rolled and warm-rolled4.The typical surface feature of the U-bent specimens after salt-spray tests: CR;(b)the CRS;(c)the HRS specimens.Fig.5.The variation in crack length of the U-bent specimens vs.testing period in the salt-spray environment:(a)maximum crack length;(b)total crack length.specimens.For all of the specimens tested in the salt-spray envi-ronment,quasi-cleavage fracture occurred in the regimes suffering from severe embrittlement ahead of notch front (Fig.7(c)).Some stepwise facets were observed in the early crack growth regions,especially for the rolled specimens (Fig.7(d)).The fracture mor-phology changed to featureless facets along with dimples of differ-ent sizes at a depth of a few hundreds of micrometers away from the severely embrittled zone (Fig.7(e)).Moreover,the occurrence of intergranular separations on the surface just beneath the notch of the sensitized specimens was noted,particularly in the WRS specimen (Fig.7(f)).It was deduced that the sensitized specimens had a tendency to show intergranular fracture in the embrittled condition.These brittle features could account for the lower NTS for the specimens tested in the salt-spray environment.3.5.Fractographic examinations of the U-bent specimenFig.8shows the fracture features and the crack path of the U-bent specimens.After salt-spray tests,assorted specimen sizes were sliced from the tested specimen then bent into two pieces after immersion in liquid nitrogen for a few seconds.Fig.8(a)and (b)reveal the half of broken specimens symmetrical to the centerline of the drilled hole.The macroscopic fracture appearance of the CR (Fig.8(a))and CRS (Fig.8(b))specimens displayed transgranular fracture was dominant at the crack initiation stage.In the case of the CRS specimen,the crack path changed from transgranular into intergranular fracture after propagating about 1mm into the specimen,as revealed in the lower portion of Fig.8(b).Overall,the fracture appearance of the WRS specimen was quite similar to that of the CRS.In addition,it was found that fine surface cracks were more likely to be along the prior austenite grain boundaries of the WRS specimen (Fig.8(c)),whereas,the main crack continued propagating in a transgranular manner.Metallographical examinations of surface cracks to reveal the crack growth path related with the microstructures were prepared by using un-broken U-bent specimens.At the crack initiation sites of all specimens,cracks were found to propagate along the slip bands (Fig.8(d)),resulting in the terrace fracture features (Fig.8(e))characterized by quasi-cleavage fracture in all of the specimens.In the case of the sensitized specimens,the transition in fracture modes from quasi-cleavage to intergranular fracture (Fig.8(f))occurred during crack growth.It is reasonable to believe that the deflected crack path along grain boundaries was strongly associated with the microstructural effects of the specimens.It has been reported the carbide precipitation at the grain boundaries would enhance the formation of martensite adjacent to the grain boundaries [13,22],thus,an increase in cracking susceptibility of the sensitized specimensoccurred.fracture appearance of the specimens after notched tensile tests:(a)the SA specimen in salt;(b)the CR specimen in air;WR specimen and (f)the WRS specimen in salt.Figs.9and 10are the EBSD maps of the CR and CRS specimens after U-bent tests.The results indicated that martensite was formed extensively in the grain interior of the CR specimen (Fig.9).Moreover,the cracks tended to propagate along the slip bands with martensite (Fig.9(a)and (b)).Such characteristics re-sulted in forming stepwise crack growth on the fracture surfaces of the specimens (Fig.8(e)).In the case of the sensitized specimen,a change in crack growth path from transgranular to intergranular fracture,as shown in Fig.8(b),should be related with the forma-tion of grain boundary martensite in the specimen shown in Fig.10.It was noticed that the crack tended to grow along a 0martensite at the grain boundary.4.DiscussionThe appearance of e martensite was expected to be located within the slip bands and a 0-martensite at the intersection of slip bands [13],which would increase the sensitivity to HE.Therefore,numerous slip bands became the most probable sites for crack ini-tiation in the U-bent specimens.At the beginning of the test,high applied strain promoted crack initiation at the slip bands,hence,cracks propagated alongside the slip bands (Fig.8(d)).This resulted in the terrace fracture features (Fig.8(e))seen in all the specimens.For the CR specimen,martensite formed extensively in the grain interior (Fig.9),thus,easing crack initiation and propagation led to a high crack growth rate in the U-bent tests.The applied strain was relieved constantly after crack growth into the specimen.Such events reduced the crack growth driving force as confirmed by the lowered crack growth rate if long crack was present,as shown in Fig.5.With a low applied strain or driving force for crack growth,the crack tended to search for the weakest path to propagate,resulting in intergranular fracture (Fig.8(f))in the sensitized spec-imen in the U-bent tests.In previous studies,the change in fracture modes from inter-granular to quasi-cleavage prior to the final (dimple)rupture has been pointed out for high strength steels suffering from HE in notched tensile tests [30,31].The decrease in tensile displacement rate or ample supply of hydrogen will cause more extensive inter-granular fracture [30,31].It was obvious that the fracture features of the embrittled specimens were related to the crack growth rate,i.e.intergranular for a low crack growth rate but quasi-cleavage for a high crack growth rate.Furthermore,the fatigue crack growth of sensitized 304/316/316L SS in gaseous hydrogen also shows a tendency of altering fracture modes from intergranular to quasi-cleavage fracture with increasing D K range [32–33].Intergranular fracture is predominant within the low D K range,which is accom-panied with the low fatigue crack growth rate for thesensitizedvarious specimens after notched tensile tests:(a)the CR specimen,(b)the WRS specimen in air;(c)the SA specimen,WRS specimen as in (d)but viewed in a plane ahead of notch front in salt-spray environment.austenitic SSs in hydrogen.Therefore,the application of low stress/strain along with an ample supply of embrittling species would as-sist in intergranular fracture of sensitized SSs.Heating during the sensitization treatment led to a recovery of cold-worked structures.It was obvious that the density of mar-tensite and slip bands in the sensitized specimens was lower rela-tive to the un-sensitized specimens;shown in the comparison of the EBSD map between the CR and CRS specimens in Figs.9and 10.The sensitized specimens were expected to have lower HE sus-ceptibility relative to the as-rolled specimens due to the reduced martensite or defects in sensitized specimens.However,grain boundaries of the sensitized specimens became the weakness,resulting in increasing the HE susceptibility of the specimens,as shown in Fig.5(b).The results of EBSD map showed the crack had a trend of growing along a 0martensite at the grain boundary (Fig.10),which was responsible for the change in fracture mode.The CR specimen had a relatively low NTS loss compared to other specimens in the notched tensile tests.However,the U-bent tests showed the reverse results;the CR specimen was more likely to crack.The difference in HE susceptibility was also associated with the extent of the brittle fracture region.Extensive brittle frac-ture was seen in all U-bent specimens,whereas,severe brittle frac-ture could only be found at the sites ahead of notch front after the tensile tests.The reasons for this observation might be that the prolonged testing period assisted brittle fracture in U bent speci-mens might be the reasons for such consequence.Constantly increasing the applied stress/strain during notched tensile tests en-hanced the austenite-to-martensite phase transformation ahead of the notch tip over a short testing interval for all samples.Such an event caused quasi-cleavage fracture of all specimens in notched tensile tests.In this study,the dissolution of surface material was accompa-nied with hydrogen absorption at the crack tip in the salt-spray environment.HE was the major mechanism for the fracture and cracking of all specimens in the salt-spray environment [6,7,34].It is known that hydrogen transport to the strained regionisof the U-bent specimens tested in the salt-spray environment:macro-fracture appearance of (a)CR and (b)CRS specimen;micrograph of WRS specimen;SEM fractographs of the (e)CR and (f)CRS specimens.assisted predominantly by mobile dislocations[35].For the SA specimen during the notched tensile tests,the ease of forming localized martensite in the plastic zone ahead of the advancing crack coupled with hydrogen transportation by dislocation motion led to severe embrittlement and a high NTS loss.Cold rolling intro-duced numerous defects,such as dislocations,slip bands and mar-tensite,which would become the additional hydrogen traps. Moreover,the hydrogen transportation to highly strained zones by newly generated dislocations would be effectively suppressed owing to the interference actions of the pre-existing dislocations. Therefore,the CR and WR specimens showed low NTS loss in notched tensile tests.The improved ductility together with benefi-cial traps for hydrogen caused the WR specimen show increased resistance to HE than other specimens tested in the salt-spray con-dition,regardless of test methods.5.Conclusions1.In the salt-spray environment,all the specimens sufferedfrom HE to various degrees in notched tensile tests.The SA specimen was the most susceptible to HE(highest NTS loss) among the specimens.The as-rolled(CR and WR)specimens had lower NTS loss than the other specimens.Sensitization treatment(CRS and WRS specimens)inevitably increased the HE susceptibility of the specimens.2.For the U-bent specimens in salt-spray environment,the SAand WR specimens were resistant to HE,which showed no cracking over the testing interval.The CR specimen had higher HE susceptibility than other specimens when consid-ering the maximum crack length.It was noticed that the HE susceptibility of CRS specimen was equivalent to that of the CR specimen when evaluated by the total crack length.The formation of many shortfine cracks in the CRS specimen resulted in the increased HE susceptibility.3.For all of the specimens tested in the salt-spray environment,quasi-cleavage fracture occurred in the regimes suffering from severe embrittlement.Stepwise facets in the embrittled regions were associated with crack growth along the slip bands with the formation of martensite in them.4.The macroscopic fracture appearance of the specimensshowed that transgranular fracture was the dominant mode at the crack initiation stage in U-bent specimen.A change in fracture mode from transgranular to intergranular fracture was observed in sensitized specimen.At the early stage of testing,the application of high stress/strain dictated crack ini-tiation and propagation along slip bands.As the crack grew into the specimen,a reduced crack growth rate was observed due to the constant relief of strain.With an ample supply of embrittling species associated with low crack growth rate, sensitized specimens predominantly displayed intergranular fracture.AcknowledgementThe authors gratefully acknowledge support for this study by the National Science Council of the Republic of China(NSC100-NU-E-019-001).References[1]A.Valiente,L.Caballero,J.Ruiz,Hydrogen assisted failure of precrackedspecimens of316L stainless steel,Nu.Eng.Design188(1999)203–216. [2]D.Eliezer,D.G.Chakrapani,C.J.Altstetter,E.N.Pugh,The influence of austenitestability on the hydrogen embrittlement and stress-corrosion cracking of stainless steel,Metall.Trans.10A(1979)935–941.[3]N.Narita, C.J.Altstetter,H.K.Birnbaum,Hydrogen-related phasetransformations in austenitic stainless steels,Metall.Trans.13A(1982) 1355–1365.[4]C.Pan,W.Y.Chu,Z.B.Li,D.T.Liang,Y.J.Su,K.W.Gao,L.J.Qiao,Hydrogenembrittlement induced by atomic hydrogen and hydrogen-induced martensites in type304L stainless steel,Mater.Sci.Eng.A351(2003)293–298.[5]H.Chen,W.Y.Chu,K.W.Gao,L.J.Qiao,Effect of hydrogen-induced martensiteon stress corrosion cracking of type304stainless steel in boiling MgCl2,J.Mater.Sci.Lett.21(2002)1337–1338.[6]Osama M.Alyousif,R.Nishimura,The effect of test temperature on SCCbehavior of austenitic stainless steels in boiling saturated magnesium chloride solution,Corros.Sci.48(2006)4283–4293.[7]Osama M.Alyousif,R.Nishimura,The stress corrosion cracking behavior ofaustenitic stainless steels in boiling magnesium chloride solutions,Corros.Sci.49(2007)3040–3051.9.(a)The microstructure and(b)the EBSD maps of the CR specimen afterU-bent test.Note that the light blue,red,and yellow areas are the c,a0and e phases,respectively.10.(a)The EBSD maps and(b)the grain boundary of the adjacent grains withdifferent orientation in the CRS specimen after the U-bent test.Note that the lightblue,red,and yellow areas are the c,a0and e phases,respectively.Science68(2013)25–33。

１ 前 言丙烯酸树脂残余单体的存在，使树脂气味大，导致自然环境受到污染，空气质量恶化，危害人们的健康，而且影响涂料涂膜的性能和应用。

因而对丙烯酸残余单体进行分析，可以了解树脂的转化率，为工艺控制和配方调整提供依据，以便最大限度地降低残余单体的含量。

目前，关于丙烯酸树脂残余单体含量的检测还没有国家标准和行业标准方法，而本方法采用气相色谱法（氢火焰离子化检测器）使丙烯酸树脂中残余单体得到较好分离，灵敏度高，重现性好，能够定量检测残余单体含量，应用于丙烯酸树脂的科研与生产中，取得满意效果。

２　实验部分２．１ 仪器ＳＣ—１００１气相色谱仪：配有氢火焰离子化检测器（ＦＩＤ）；色谱柱：５％　１，２—丙二醇己二酸聚酯填充柱，３ｍｍ×２ｍ；微量注射器：１０μＬ，５０μＬ；配样瓶：１０ｍＬ，具有可密封瓶塞；移液管：５ｍＬ。

２．２　试剂和材料载气：氮气，纯度≥９９．８％；燃气：氢气，纯度≥９９．８％；助燃气：空气；乙酸丁酯，甲基丙烯酸甲酯（ＭＭＡ），丙烯酸丁酯（ＢＡ），苯乙烯（Ｓｔ），丙烯酸—β—羟丙酯（ＨＰＡ），丙烯酸（ＡＡ），均为分析纯。

２．３ 样品前处理２．３．１　稀释样品精确称取样品１　ｇ左右（精确至０．０００２ｇ）于配样瓶中，再称取４ｇ左右乙酸丁酯，使样品完全溶解在乙酸丁酯中，备用。

２．３．２　标准样品的配制用移液管取５ｍＬ乙酸丁酯于配样瓶中，再用微量注射器按表１所示的体积数将分析纯的甲基丙烯酸甲酯、丙烯酸丁酯、苯乙烯、丙烯酸—β—羟丙酯、丙烯酸加入到配样瓶中，精确称取所有化合物的总质周亚莉（重庆三峡油漆股份有限公司，４０００５１）摘要：乙酸丁酯稀释丙烯酸树脂后，用气相色谱法使丙烯酸树脂中的各种残余单体得到较好分离，再采用氢火焰离子化检测器（ＦＩＤ）定量测定。

该方法灵敏度高，重现性好，应用于丙烯酸树脂的科研与生产中，取得满意效果。

关键词：气相色谱法；残余单体；丙烯酸树脂；氢火焰离子化检测器（ＦＩＤ）中图分类号：ＴＱ６３０．７＋２ 文献标识码：Ｂ 文章编号：１００６－２５５６（２００６）０３－００３３－０２量为４．４１３ｇ，并充分摇匀（此标准样品当天配制）。