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Vol.54 N o.4 Apr. 2021凝固冷却速率对2507超级双相不锈钢微观组织的演变及耐蚀性能的影响沈楚，邹德宁，赵洁，陈阳(西安建筑科技大学冶金工程学院，陕西西安710055)[摘要]为探究凝固冷却速率对2507超级双相不锈钢微观组织与耐蚀性能的影响，采用光学显微镜（0M)和 扫描电子显微镜（S E M)研究了不同凝固冷却速率2507超级双相不锈钢的微观组织演变规律，并结合Image-P r o图像分析软件与铁素体分析仪，确定了各不同凝固冷速试样组织中的各相含量，得到了凝固冷却速率对c t相析出的 影响规律及(T相的析出机理。
再采用动电位极化法与交流阻抗谱法研究了各不同凝固冷却速率2507超级双相不 锈钢的耐蚀性能。
结果表明：试样组织中的（T析出相含量随着凝固冷却速率的降低而增加，试样的耐蚀性能随着 凝固冷却速度的降低而减弱。
[关键词]2507超级双相不锈钢；凝固冷却速率；<7析出相；微观组织；耐蚀性能[中图分类号]T G506.7+1 [文献标识码]A[文章编号]100卜1560(2021)04-0074-06Effect of Solidification Cooling Rate on the Microstructure Evolution andCorrosion Resistance of 2507 Super Duplex Stainless SteelS H F.N C h u,Z O U De-ning, Z H A O Jie, C H E N Y a n g(School of Metallurgy and Engineering, X i*a n University of Architecture and Technology, X i'a n 710055, China)Abstract：For exploring the influence of solidification cooling rate on the microstructure evolution and corrosion resistance of 2507 super duplex stainless steel, the law of the microstructure evolution of 2507super duplex stainless steel with different solidification cooling rates was investigated by optical microscope (O M)and scanning electron microscope (S E M). T h e contents of each phase in the samples with different solidification cooling rates were determined by Image-Pro image analysis software and ferrite analyzer, and the effect of solidification rate on the precipitation of a phase and the precipitation m e c h a n i s m of a phase were obtained. Furthermore, the corrosion resistance properties of 2507 super duplex stainless steel with different solidification and cooling rates were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. Results showed that the content of a phase in the samples structure increased with the decrease of solidification cooling rate, and the corrosion resistance of the samples weakened with the decrease of solidification ccxjling rate.Key words：2507 super duplex stainless steel；solidification cooling rate；a p h ase；microstructure；corrosion resistance〇前言2507超级双相不锈钢是超低碳并具有较高合金含 量的一种高性能不锈钢，它兼具有铁素体不锈钢和奥 氏体不锈钢的优点，而其中最为突出的是它具有比普 通双相不锈钢更优异的耐腐蚀性能。
第43卷第1期50 2021 年 1 月上海金属SHANGHAI METALS Vol. 43 , No. 1January , 2020热轧后冷却速度和卷取温度对汽车用低合金高强钢板中析出物的影响王畅"2于洋"2王林"2张亮亮李振2陈瑾2(•首钢技术研究院，匕京100043； 2.绿色可循环应铁流程北京市重点实验室，北京100043；3.首首股份公司迁安钢铁公司，河北迁安064404)【摘要】采用Gleeble-3500热模拟试验机研究了层流冷却速度和卷取温度对汽车用低合 金高强钢板热轧过程中析出行为的影响。
结果表明：热轧过程中钢中析出物主要为多边形Nb (C,N)和细小NbC ；随着热轧后层冷速度的增大，析出物尺寸减小、长大速度减慢，其密度从 200个/p m 2减少到了 50个/p m 2。
试样热轧后层冷至400 C 的卷取过程中，由于析出驱动力不足，析出物的数量骤减，其密度从250个/ p m 2减小到了 25个/ p m 2。
控制热轧过程中析出物的 尺寸和数量并尽量减少含Nb 析出物的数量，有利于连续退火后得到细小均匀的组织，产生细晶强化和析出强化的双重强化效果。
【关键词】 低合金高强钢 第二相 析出 铌 层冷速度 卷取温度Effect of Cooling Rate and Coiling Temperature after Hot- rolling onPrecipitates in Low- alloy High- strength Steel for AutomobileWANG Chang 1'2 YU Yang 1'2 WANG Lin 1'2 ZHANG Liangliang 1，LI Zhen 2 CHEN Jin 2(1. Shougang Research Institute of Technology , Beijing 100043 , China ; 2. Beijing Key Laboratory ofGreen Recyclable Process for Iron and Steel Production Technology , Beijing 100043 , China ;作者简介:王畅，女，硕士，高级工程师，主要从事热轧及冷轧产品表面质量控制工作,E-mail ： ustb 0321033@3. Qian'an Iron and Steel Company of Shougang Co. , Ltd. , Qian'an Hebei 064404, China )【Abstract 】 Effect of laminar cooling rates and coiling temperatures after hot-rolling on precipitating behavior of low-alloy high-strength steel plate for automobile was investigated by aGleeble- 3500 thermal simulation test machine. The results showed that phases precipitated during hot-rolling were predominantly polygonal Nb (C,N ) and fine NbC , and as the laminar cooling rateafter hot- rolling increased , the precipitates became finer and grew more slowly , with their number density decreasing from 200 per p m 2 to 50 per p m 2. The precipitates in the sample undergoing hot-rolling and laminar cooling to 400 C followed by coiling decreased drastically in amount ，with their number density decreasing from 250 per p m 2 to 25 per p m 2, because of insufficient precipitation driving force. The control of both amount and size of the phases precipitated during hot- rolling and minimizing the amount of niobium- containing precipitates will help to obtain fine and uniform structureand to develop double strengthening effects of fine-grained strengthening and precipitationstrengthening after continuous annealing .【Key Words ] low-alloy high-strength steel , second phase , precipitation , niobium , laminar cooling rate ，coiling temperature第1期王畅等:热轧后冷却速度和卷取温度对汽车用低合金高强钢板中析出物的影响51为了满足减重节能的需要,汽车零部件越来越多地采用高强度钢板制造。
张哲，郎元路，吴巧燕，等. 降温速率对梨瓜细胞冻干特性的影响[J]. 食品工业科技，2022，43（19）：31−42. doi: 10.13386/j.issn1002-0306.2021120035ZHANG Zhe, LANG Yuanlu, WU Qiaoyan, et al. Effect of Cooling Rate on Freeze-drying Characteristics of Pear Melon Cells[J].Science and Technology of Food Industry, 2022, 43(19): 31−42. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2021120035· 研究与探讨 ·降温速率对梨瓜细胞冻干特性的影响张 哲*，郎元路，吴巧燕，张志强，陈佳楠，计宏伟，田津津（天津商业大学机械工程学院，天津 300134）摘 要：为了探究降温速率对梨瓜细胞冻干过程中的影响，基于低温显微镜成像及真空冷冻干燥技术，对梨瓜细胞进行了不同降温速率（5、15、25、35、50 ℃/min ）下的冻干可视化实验，分析了脱水干燥过程中的细胞形态学参数（当量直径、面积、周长、体积）以及内压在冻干过程中的变化规律，并对干燥组织的多孔物料特征参数（孔隙率）进行了研究。
结果表明：冻结温度随着降温速率的增长整体呈逐渐降低的趋势；冻干过程中，降温速率为25 ℃/min 时，细胞形态学参数和内压变化最小，其中，细胞形态学参数变化率与内压均随降温速率的增大呈先减小再缓慢增加的趋势；过高和过低的降温速率下，梨瓜细胞形态与内压变化较大，不利于梨瓜的冻干处理；当降温速率大于5 ℃/min 时，孔隙率较大且受降温速率的影响较小，只在一定范围内发生微小波动；梨瓜的最佳降温速率为25 ℃/min ，该降温速率下的细胞形态及溶质损害最小。
塑化聚乙烯醇的流变性能及发泡行为研究吴文倩;贾青青;高伦巴根;项爱民【摘要】采用毛细管流变仪对聚乙烯醇（PVA）的流变性能进行了表征，用差示扫描量热仪研究了降温速率对PVA结晶性能的影响，并通过在PVA中添加化学发泡剂熔融挤出的方法制备了PVA发泡材料，用扫描电子显微镜和密度测试仪分别对发泡材料的泡孔形态和密度进行了表征。
结果表明，PVA对剪切作用非常敏感，在低剪切速率下熔体黏度较大，泡孔分布均匀，材料密度较小；在高剪切作用下熔体黏度低，气体容易逃逸，导致发泡材料泡孔破裂或合并；低降温速率下熔体黏度小，泡孔易合并、塌陷；在较高的降温速度下，由于气体压力过大而造成气泡合并、连通，材%The rheological behavior of plasticized poly （vinyl alcohol）（PVA） was investigated with capillary rheometer. The effect of cooling rate on crystallization properties of PVA was studied with differential scanning calorimetry analyzer （DSC）. The PVA foams were fabricated by filling chemical foaming agent through melt extrusion, and the cell morphology and the density of the foams were investigated with scanning electron microscope （SEM） and density tester. It showed that PVA was sensitive to the shearing effect. At low shear rate, the melt viscosity of PVA was high, leading to the homogeneous distribution of the cells and a low density; at high shear rate, the melt viscosity of PVA was low and the gas was easy to escape, leading to the break or combination of the cells. At lower cooling rate, the melt viscosity was lower, leading to the combination or collapse of the cells. At higher cooling rate, the cellcombined due to the excessive gas pressure, resulting in the higher density of the foams.【期刊名称】《中国塑料》【年(卷),期】2011(025)008【总页数】6页(P69-74)【关键词】聚乙烯醇;流变性能;结晶性能;泡孔形态;表观密度【作者】吴文倩;贾青青;高伦巴根;项爱民【作者单位】北京工商大学材料与机械工程学院,北京100048;北京工商大学材料与机械工程学院,北京100048;北京工商大学材料与机械工程学院,北京100048;北京工商大学材料与机械工程学院,北京100048【正文语种】中文【中图分类】TQ325.9PVA是亲水性很好的环境友好高分子材料。
TA039Interpreting Unexpected Events and Transitions in DSC ResultsFigure 1: Artificial DSC curveINTERPRETATION OF EVENTS AND TRANSITIONSEvent 1: Large Endothermic Start-up Hook CausesAt the beginning of a programmed heating experiment, there may be significant baseline change (usually endothermic) which occurs primarily based on differences in the heat capacity of the sample and reference. Since heat capacity is directly related to weight, an endothermic shift indicates that the reference pan is too light to offset the sample weight. This effect is heightened by faster heating rates.When operating subambient, the thermocouple junctions in the DSC cell base may get cold as cold is transferred from the cell cooling head. This effect increases as the temperature is lowered and/or the time at lower temperatures is increased.Effects on ResultsA large “start-up hook” or a sloping baseline make detection of weak transitions difficult. In addition, during the first 2-3 minutes of the experiment, transition temperatures and measured heat flow (DH) may not be reproducible.SolutionsUsing aluminum foil or additional pan lids, make upINTRODUCTIONThe purpose of this paper is to assist DSC users with interpretation of unusual or unexpected transitions in DSC results. The transitions discussed in the paper are several of the ones that most frequently create problems for the new user, and which can also fool even an experienced thermal analyst.By applying some of the recommended procedures and solutions, most laboratories will be able to improve the overall quality and interpretation of DSC results.BACKGROUNDDifferential scanning calorimetry (DSC) is a thermal analysis technique which measures the temperature and heat flow associated with transitions in materials as a function of temperature and time. Such measurements provide quantitative and qualitative information about physical and chemical changes that include endothermic/exothermic processes or changes in heat capacity. Specific information that can be obtained include:• Glass transition temperatures • Melting points & boiling points • Crystallization time & temperature • Percent crystallinity• Heats of fusion and reaction • Specific heat• Oxidative stability • Rate of cure • Degree of cure • Reaction kinetics • Purity• Thermal stabilityBecause of the wealth of information provided and because DSC is easy-to-use, DSC has become the most commonly used thermal analysis technique. Ease-of-use in this case refers to sample preparation and experimental setup, as well as interpretation of the results. There are, however, some common DSC events/transitions that can be the cause of less than optimum results and/or misinterpretation. This paper describes several of these events with causes and solutions. Figure 1 is an artificial DSC curve which was generated to illustrate these events/transitions. The curve is artificial in the sense that all of these events would not occur in the same real world DSC curve.a series of reference pans of different weight (2 mg. increments). When running a sample use a reference pan that weighs 0–10% more than sample pan. Figure 2 shows results with an epoxy prepreg sample. Best results are achieved with 1.5 lids. 2 lids results in overcompensation and an exothermic start-up hook. Figures 3 and 4 show how the glass transition results are affected by correct compensation. Note: these results are obtained heating at 20°C/minute from a 100°C isothermal hold. The impact of the start-up hook can also be reduced by initiating the heating at a temperature that is at least 2-3 minutes below the range of interest at the heating rate chosen (ie. at 20°C/minute, start experiment at least 50°C belowthe first thermal event of interest.)Figure 2: Effect of reference pan weightFigure 3: Start-up hook and T gwith no reference panFigure 4: Start-up hook and T g with correct reference panIf operating below 0°C, use 50cc/minute dry nitrogen purge gas through the cell base VACUUM PORT plus the normal purge gas. Figure 5 illustrates the typicalimprovement obtainable.Figure 5: Proper gas purging improves subambient baselineperformanceEvent 2: Transition(s) at 0°C CausesWeak transitions around 0°C indicate the presence of water in the sample or the purge gas. These transitions are usually endotherms, but may appear different than a melting peak. Since water can condense on both the sample and reference pans, the transition often appears as shown in Figure 6. Furthermore, the peaks may appear slightly lower than 0°C due to impurities dissolved by the moisture from the cell and pans.Effects on ResultsIf water is in the sample, results may not be reproducible because it can act as a plasticizer and reduce transition temperatures. The water will also volatilize during the run, causing an endothermic peak and a shift in the baseline.If water is in the purge gas, it causes a perturbation in the baseline that makes it difficult to detect real transitions near 0°C.SolutionsK eep hygroscopic samples in a dessicator and load them into pans in a dry box.Weigh the complete sample pan (with sample) before and after the run. A change in weight could explain anunexpected transition.Figure 6: DSC transition due to moisture in the purge gasDry the purge gas by placing a drying tube in the line. Figure 7 shows an epoxy sample after loading at -100°C. The absence of any transitions at 0°C indicates that with proper precautions water condensation in the cell can be eliminated even under conditions which favor condensation. Note: Loading a sample at temperature below 0°C is only possible when using the liquid nitrogen cooling accessory (LNCA). Samples should always beloaded above 0°C with any other cooling accessory.Figure 7: Quench cooling samples at subambient temperaturesEvent 3: Apparent “Melting” at Glass Transition (T g )CausesStresses built into the material as a result of processing, handling or thermal history are released when the material is heated through its glass transition. The reason this occurs at T g is that the molecule goes from a rigid to a flexible structure and thus can move to relieve the stress.Effects on ResultsMolecular relaxation usually appears as a weak endothermic transition near the end of a glass transition. As shown in Figure 8, this behavior can be pronounced enough to either shift the measured glass transition temperature several degrees or lead to misinterpretation of the T gas an endothermic melting peak.Figure 8: Molecular relaxation can cause T g to appear as a meltSolutionsRelieve the internal stresses in the material by heating it to at least 25°C above the T g and then quench cooling it to a temperature below the T g . Figure 9 shows the same material as in Figure 8 after curing at 200°C and thenquench cooling to 25°C.Figure 11: DSC scan of PET after quench coolingFigure 10: Effect of cooling rate on shape of T gEvent 4: Exothermic Peaks Below Decomposition Temperature While Heating CauseExothermic behavior results during curing of a thermosetting resin or crystallization of a thermoplastic polymer. The amount of heat associated with these transitions can be used to determine degree of cure and % crystallinity respectively provided scans of suitable standards are available.When an exotherm is obtained in a polymer’s DSC profile at a temperature which the operator suspects is too low to be a decomposition, running the material in the TGA aids evaluation. The absence of a TGA weight loss which coincides with the DSC exotherm indicates that the exotherm is crystallization or curing.Effects on ResultsThe presence or absence of exothermic crystallization peaks in thermoplastic materials is very dependent on thermal history. Therefore, DSC results will not be reproducible if thermal history of the sample is not tightly controlled. Figures 11 and 12 illustrate the different results obtained for PET after quench cooling and programmed cooling at 10°C/minute respectively. The quenched material has a well-defined T g indicating significant amorphous structure which rearranges on heating to a crystalline structure before melting at about 235°C. The DH of crystallization is slightly less than the DH of melting which indicates that the initial structure is mostly amorphous. The slowly cooled material has a weak T g , indicating an initial structure that is almost entirely crystalline. Since it is crystalline at the start of the DSC experiment, no additional crystallization occurs prior to the melt at 235°C.SolutionsWhen comparing thermoplastic materials, give the materials a common known thermal history by either quench cooling or program cooling from above the melting temperature. ASTM D3418-82 defines recommended procedures for giving polymers a knownthermal history.Figure 11: DSC scan of PET after quench coolingFigure 12: DSC scan of PET after slow cooling Event 5: Baseline Shift After Endothermic or Exothermic Peaks CausesBaseline shifts are caused by changes in sample weight, heating rate, or the specific heat of the sample. A change in specific heat often occurs after the sample has gone through a transition such as curing, crystallization, or melting. Sample weight often changes during volatilization or decomposition.Effects on ResultsSince ΔH is calculated on the basis of sample weight (J/g, BTU/lb, etc.), any calculation of DH after a weight change will be in error.Integration of a peak which has a baseline shift is difficult and typically less accurate because of operator subjectivity in setting integration limits and baseline type.SolutionsWeigh the sample before and after a run to determine if weight loss has occurred.If crystallization or melting is the cause of the transition, compare the DH of the transitions, using different limits and types of baselines. Figure 13 illustrates an example where useof sigmoidal baseline is required.Figure 13: DSC scan of PET crystallization and T g on coolingEvent 6: Sharp Endothermic Peaks During Exothermic Reactions CausesSharp peaks similar to those in Figure 1 above 300°C, are usually the result of experimental phenomena rather than real material transitions. For example, rapid volatilization of gases trapped in the material can cause sharp peaks, as can rapid volatilization of gases trapped in a partially sealed hermetic pan.Effects on ResultsErroneous interpretation of these sharp endotherms as melting peaks associated with minor components is possible.Volatilization can be detrimental to obtaining accurate quantitative results since sample mass changes. If the volatiles are corrosive, such as halogenated flame retardants, DSC cell damage can occur with extended operation.SolutionsWeigh the sample before and after the run to determine if weight loss has occurred.Reduce the temperature limit of further experiments if no useful information is obtained because of the e a Pressure DSC cell.By Leonard C. ThomasFor more information or to place an order, go to to locate your local sales office information.。
Ti 穀臧Vol. 38 No. 1February 2021第38卷第1期2021年 2月TA12A 钛合金热处理过程中等轴和片层！相演变行为研究陈飞1,周瑜2,王柯2(1.陕西宏远航空锻造有限责任公司，陕西 咸阳713801)(2.重庆大学材料科学与工程学院，重庆400044)摘要：对近a 型TA12A 钛合金进行热处理实验，利用扫描电子显微镜(SEM )和电子背散射衍射！ EBSD )技术对热处理后的微观组织进行观察，研究了两相区固溶温度和冷却速率对微观组织的影响。
研究表明：TA12A 钛合金在980和1000 ＞保温后冷却时，"相向a 相转变，一方面可以使得等轴a 相长大，另一方面也可析出片层a 相。
等轴 a 相长大过程中，大的区域与初始 a 相存在成分差异，从 大的区域在背散射电子成像模式下表现出a 环状组织。
空冷时，因冷却速率较快，使得片层a 相快速大，从而抑制了等轴a 晶粒的长大。
但是，固溶温度对 a 晶粒的长大和 a 相的 行为影响 。
同时，冷却速率显著影响 a 相的 ，这与等轴a 相的含量密切相关$关键词：TA12A 钛合金；热处理；等轴a 晶粒；片层a 相中图分类号：TG166. 5 ； TG146. 23文献标识码：A 文章编号：1009-9964(2021 )01B001-05Evolution of Equiaxed and Lamellar a Phase during Heat Treatment of TA12A Titanium AlloyChen Fei 1，Zhou Yu 2，Wang Ke 2(1. Shaanxi Hongyuan Aviation Forging Company Ltd.，Xianyang 713801，China )(2. School of Materials Science and Engineering ，Chongqing University ，Chongqing 400044，China )Abstract : Heat treetmeni expermenis werr conducted on the neer-9 titanium Hoy TA12A. The microstructurr was observed using sccnning electron microscopy ( SEM) and electron backscattered difraction ( EBSD) method, and theeffect of solution Omperature in tmo phase region and cooling rate on the microstructure evolution wat 0x 630164. The resultt show that ，during the cooling proceso after holding at 980 and 1000 ＞，the transformation from " phase te aphase could make equiaxed a grain grow up and Umellar a phase precipimm. During the growth of equiaxed a grain ， the composition of the new-9rowth region is dnferent from that of the initial equiaxed a grain ，which makes the new-growth region show an a eng structure under the SEM observation. The air cooling makes the lamellar a phase nucleate and grow rapidly ，thus inhibiting the growth of equiaxed a graine. However ，the solution temperature has little effecOon thegoowth otequoaeed a goaon and thepoecopotatoon otaameaao a phaee.Fuotheomooe ， thecooaongoatehaeaeognotocanafect on the nucleation site of lamellar a phase ，which is closely related te the content of equiaxed a grain.Key words ： TA12A titanium Cloy ； heat treetment ； equiaxed a grain ; lamellar a phase钛合金具有比强度高、断裂韧性好、高温性能， 航空航一 重要的金属材料。
Cooling Curves(冷却曲线)Fig shows the effect of cooling rate on the formation of different reaction products, e.g., pearlite, bainite and austenite.(1)Cooling curve-a: Very slow cooling rate, typical ofconventional annealing. Transformation product is coarsepearlite with low hardness.(2)Cooling curve-b: Transformation will start at 3 with theformation of coarse pearlite and finish at 4 with theformation of medium pearlite. Since there is a greatertemperature difference between point 3 and 4 than there isbetween 1 and 2, the structure will show a greater variationin the fineness of pearlite and a smaller proportion of coarsepearlite and a smaller proportion of coarse pearlite ascompared to that of curve-a.Curve-b involves a faster cooling rate than curve-a(annealing) and may be considered typical of normalizing.(3)Cooling curve-c: This curve is typical of a slow oil quenchand the microstructure will be a mixture of medium and finepearlite.(4)Cooling curve-d: This curve is typical of an intermediatecooling rate and austenite will start to transform (at point 5)to fine pearlite. As Ms line is crossed, the remaining austenite will transform to martensite. The final structure at room temperature will thus consist of martensite and fine pearlite.(5)Cooling curve-e: This curve is typical of a drastic quench,the substance remains austenitic until the Ms line is reached, and changes to martensite between the Ms and M f lines. (6)Cooling curve-f obtains a bainitic structure by coolingrapidly enough to miss the nose of curve and then holding in the temperature range at which bainite is formed until transformation is complete.(7)Cooling curve-g: This curve is tangent to the nose of TTTcurve. The cooling rate associated with curve-g is approximate critical cooling rate (CCR) for this steel.Any cooling rate equal to or faster than CCR (e.g., cooling rate-e) will form only martensite and any cooling rate slower than CCR (e.g., cooling rates a, b and c) will form some softer transformation products such as pearlite or bainite.（下页是冷却曲线和时间、温度、转变关系图（奥氏体转变））timeBainite 贝氏体conventional 惯例的；常规的Anneal 退火（动）annealing 退火（名）Coarse 粗糙；未加工的variation 变化；变动Fineness 细度；细化程度normalize 正火，把······正火Normalizing 正火quench 淬火，淬硬；急冷Quenching 淬火intermediate 中间的；居中的Drastic 急剧的；猛烈的drastic quench 急冷；急淬Miss 未碰到；未击中TTT diagram=Time-Temperature-Transformation diagram 时间、温度、奥氏体转变关系图Tangent 切线，正切；相切的tangent to 与······相切Associate with ·······与······相联系martensite 马氏体。
