Effect of aging on the corrosion resistance of 2101lean duplex stainless steel
Lihua Zhang a ,Yiming Jiang a ,Bo Deng a ,Wei Zhang b ,Juliang Xu a ,Jin Li a,?
a Department of Material Science,Fudan University,Shanghai 200433,PR China b
Institute of stainless steel,Baosteel Co.,Ltd,Shanghai 200431,PR China
A R T I C L E D A T A
A B S T R A C T
Article history:Received 7May 2009Received in revised form 14August 2009
Accepted 29August 2009The microstructure and localized corrosion behavior of a 2101lean duplex stainless steel aged at 700°C were investigated.The results showed that changes in the microstructure of the duplex stainless steel,due to the formation of precipitates,affected its pitting corrosion resistance.The values of the pitting potential and the critical pitting temperature dropped drastically before aging time up to 30min.The potentiostatic pitting corrosion measurement indicated more sensitive to the small amount of precipitates compared to the potentiodynamic test.Pitting nucleated mainly in the ferrite phase for the solution-annealed specimen,while the initiation of pitting corrosion for the aged specimen took place at Cr-depletion area around the precipitates,i.e.in the newly formed secondary austenite phase.
?2009Elsevier Inc.All rights reserved.
Keywords:
Duplex stainless steel Aging Precipitation Pitting corrosion
1.Introduction
Duplex stainless steels (DSS)are being increasingly employed in chemical,petrochemicals,nuclear,and marine industries primarily due to their excellent mechanical property in combination with good corrosion performance [1].It is well established that DSS exhibit optimum properties when their ferrite to austenite (α/γ)volume ratios are about 1:1[2]and no other tertiary phases are present.However,during fabrication,such as welding and other thermal treatments,the ferrite to austenite volume ratios may be changed along with the precipitation of various compounds (e.g.chromium carbides and nitrides)and some other intermetallic phases (like sigma (σ),chi (χ),secondary austenite (γ2))[3–5].These microstruc-tural modifications have a detrimental effect on mechanical and corrosion resistance properties of the DSS.A significant amount of work,that studied the effect of heat treatment and
precipitation on the corrosion behavior of commonly used DSS grades such as 2205(UNS S32205),2304(UNS S32304),and 2507(UNS S32507),had been published [6–9].
Since 2000,with the high fluctuation of the nickel price,DSS 2101(EN 1.4162,UNS S32101)containing less than 2%nickel has made it attractive.The reduced nickel content is compensated by an increase in the amount of manganese and nitrogen in the steel to stabilize the austenite phase in duplex microstructures [10].The molybdenum content of this steel is also significantly reduced to limit the precipitation of delete-rious phases.Liljas [11]in the review article on DSS 2101explored the utility of this new duplex family in a wide variety of applications,replacing austenitic steels of type 304and also,to some extent,structural steels.Westin [12]addressed the effect of alloying elements and thermal cycles on phase balance and microstructure in the high temperature heat-affected zone (HTHAZ)of DSS 2101.The authors [13]also
M A T E R I A L S C H A R A C T E R I Z A T I O N 60(2009)1522–1528
?Corresponding author.Tel.:+862165643648;fax:+862165643648.E-mail address:jinli@https://www.doczj.com/doc/cc6424420.html, (J.
Li).
1044-5803/$–see front matter ?2009Elsevier Inc.All rights reserved.doi:
10.1016/j.matchar.2009.08.009
a v a i l a
b l e a t w w w.s
c i e n c e
d i r
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w w w.e l s e v i e r.c o m /l o c a t e /m a t c h a r
investigated the effect of annealing temperatures in the1000–1200°C range on the microstructure and corrosion behavior of 2101lean duplex stainless steel.Despite some studies on the DSS2101,research about the microstructure and properties of DSS2101is still limited[14,15].Very little data are available on the corrosion resistance,especially the pitting corrosion in the existence of precipitation.Exposure of DSS to temperature above~350°C can result in the formation of precipitates, depending on the temperature and duration of exposure[16]. The presence of these precipitates may lead to chromium depletion in the adjacent matrix,adversely affecting the localized corrosion resistance of steels.Sigma phase(σ)was found to have the strongest influence on toughness and corrosion resistance because of its relatively large volume fraction and rapid formation[17,18].Secondary austenite(γ2) had lower chromium content as compared to the former austenite,resulting in a poorer corrosion resistance[19].Cr2N particles had been believed to be nucleation sites for pitting [20].Therefore,the examination of the effect of precipitation on the pitting corrosion within DSS would be very effective in improving their overall corrosion resistance.Zhang[21]found that DSS2101aged at700°C had minimum impact energy when subjected to thermal aging at temperatures from500to 1050°C for30min,and investigated the precipitation behavior of DSS2101aging at700°C and its effect on the mechanical properties.This aim in this work concerned the influence of precipitation on the corrosion behavior of DSS2101aging at 700°C in chloride solution.
2.Experimental
The material was a hot-rolled2101duplex stainless steel plate (EN1.4162,UNS S32101)with the following chemical compo-sition in wt.%:21.4Cr,5.7Mn,1.2Ni,0.31Mo,0.23N,0.03C,0.4 Si,0.019P,0.005S,balance Fe.The specimens were subjected to solution-annealed at1050°C for30min,followed by water quenching.Then,they were isothermally aged at700°C for different times in the3min to240min range,and quenched by water.
The electrochemical measurement was carried out with a PARSTAT2273potentiostat.A platinum foil and a saturated calomel electrode(SCE)were used as the counter electrode and reference electrode,respectively.Unless otherwise stated in this paper,all potentials recorded were referred to SCE.The specimens acting as the working electrodes were embedded in epoxy resin.Prior to each experiment,the working electrode was ground mechanically using successive grade emery papers up to1500grit,polished with1.5μm alumina water suspension,rinsed with distilled water and dried in air.In order to avoid crevice corrosion,the interfaces between specimen and resin were sealed with special silica gel sealant and dried in the air.The exposed electrode surface area was 1cm2.The test solution,1mol L?1NaCl,was made up from analytical grade reagents and distilled water.
Potentiodynamic polarization measurement was con-ducted at30±1°C with a scan rate of0.33mV s?1,from ?300mV SCE(lower than the open circuit potential)to the potential where the current indicated that stable pitting or transpassivity had occurred.Pitting potential(E p)was identi-fied as the potential where the current density continuously exceeded100μA cm?2.On the other hand,potentiostatic measurement was performed to obtain the critical pitting temperature(CPT)by applying an anodic potential of250mV SCE and continuously increasing the electrolyte temperature at a rate of1°C min?1until stable pitting occurred.The CPT was defined as the temperature at which the current density reached100μA cm?2.The electrolyte was bubbled with pure nitrogen gas(N2)to get rid of the oxygen gas(O2)throughout the whole test.Each type of electrochemical measurements was repeated at least three times.Any crevice corrosion observed on the specimen after testing means that the test results were invalid and must be discarded.
For the microstructure study,the aged specimens were electrochemically etched in a30%KOH solution.This etching process made precipitates appear black,austenite phase bright and ferrite phase gray.Scanning electron microscope (SEM,FEI Quarter400)with a Robinson backscattered electron detector was used to observe the microstructure evolution during isothermal aging and the morphology of pits.Mean-time,the composition of different phases was analyzed by energy dispersive X-ray spectroscope(EDS),which attached to scanning electron microscope(SEM).
3.Results and Discussion
3.1.Microstructure
Fig.1shows a series of micrographs of the specimens aged at 700°C for various aging times.The solution-annealed material was characterized by a ribbonlike microstructure,consisting of elongated austenite islands in the ferrite matrix.No intermetallic precipitate was seen in Fig.1(a).Aging at700°C for6min,few of nucleated intermetallic precipitates were observed at theα/γinterfaces.After a certain aging time of 30min,the intermetallic precipitates along the phase bound-ary were noticeable and some precipitates were also observed atα/αinterfaces in the specimen.With the further increase of aging time to240min,the amount of intermetallic precipi-tates increased drastically along theα/γinterfaces andα/αinterfaces,as shown in Fig.1(d).
For the composition analysis of different phases,EDS was performed on the unetched specimen aged at700°C for 240min.To obtain reproducibility,10different areas were analyzed and the average composition of these phases was given in Table1.From the micrographs and EDS results,it could be found that the precipitates formed in theα/γinterfaces andα/αinterfaces had a high-chromium content. Meantime,the lighter region near the precipitates showed lower chromium content as compared to other phases,i.e. ferrite phase,austenite phase and precipitates.This low-chromium region was regarded as the so-called secondary austenite phase(γ2)[22].In related work performed[21],the precipitates formed in DSS2101,aged at700°C,were identified as Cr2N by using X-ray diffraction analysis(XRD) and transmission electron microscope(TEM),together with Thermo-Calc software.Hence,from the experimental result
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and published work,it could be deduced that the high chromium-containing precipitates formed in the α/γinter-faces and α/αinterfaces were Cr 2N,which also resulted in the formation of low chromium-containing secondary austenite.The content of precipitates and secondary austenite was not determined quantitatively,since it was hard to evaluate small precipitates,e.g.chromium nitrides [23].3.2.Pitting Corrosion Behavior
The influence of isothermally aging on the pitting corrosion resistance was estimated with potentiodynamic polarization measurement.Fig.2shows the typical polarization curves of the aged specimens exposed to 1mol L ?1NaCl solution.It appeared from the diagram that the aging time affected the passivation properties of the steel.The polarization curves of
specimens aged before 6min was similar to the one of the solution-annealed specimen.These curves showed lower passive current density values (i pass was almost equal to 1×10?6A cm ?2)and larger passive potential regions.However,longer aging time (from 15min to 240min)increased the susceptibility of the steel to the localized corrosion.As a matter of fact,the passive potential rang decreased
noticeably
Fig.1–Scanning electron micrographs of specimens aged at 700°C for:(a)solution-annealed,(b)6min,(c)30min,and (d)240min.Secondary electron image (SEI)in (a),(b),and (c);backscattered electron image (BEI)in (d).
Table 1–EDS analysis (wt.%)of different phases present in DSS 2101aged at 700°C for 240min.Phase
Fe
Cr
Ni
Mo Mn
Ferrite (α)69.5423.730.860.53 5.18Austenite (γ)
70.6020.69 1.480.42 6.07Depleted zone near the precipitation 71.8618.66 2.020.49 6.36Precipitation
58.77
34.95
0.72
0.34
5.2
Fig.2–Polarization curves obtained for DSS 2101in 1mol L ?1NaCl solution aged at 700°C for different times.
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and the passive current density increased relatively,especially at aging times of 120min and 240min.The reduction in the passive potential range and the increase in the passivity current density may be attributed to the increased amount of precipitates in the matrix,as shown in the microstructure evolution of Fig.1.Many current peaks,associating with events of metastable pitting [24],were observed before the appearance of E p in all tested specimens.It was found from Fig.2that the amount of metastable pitting had no much relating with the increasing of aging time.
In order to corroborate the polarization data,potentiostatic CPT measurement also was performed in chloride solution.The typical curves of current density versus temperature for the aged specimens were showed in Fig.3.The CPT curves for the solution-annealed specimen and for the specimens aged before 10min were almost identical.It was found that the current density kept steady at a lower value of about 1×10?6Acm ?2during the initial heating,corresponding to the stainless steel protected well by the passive film.As the temperature increased further above the CPT,the current density rose abruptly and increased continuously,indicating the occurrence of stable pitting.However,the curves of the specimens aged for longer than 10min were apparently different from those of specimens aged for shorter time.With approaching CPT,the specimens aged for more than 10min showed a moderate increase in current density due to the occurrence of selective corrosion around precipitates.In addition,the passivation current density of specimens aged for more than 10min was slightly higher than that of specimens aged for shorter time.This seemed to be related to the increased amount of precipitates as the aging time increased.Meantime,metastable pits were also observed before the appearance of CPT in all tested specimens.
The effect of aging time on the E p and CPT is present in Fig.4.A variation of 10mV~30mV in the E p curve was found before aging time of 6min.With the increase of aging time,the E p values sharply dropped between 10min and 30min.When aging time was longer than 120min,the E p of specimens gradually came to a steady value of about 100mV.The curve of CPT versus aging time present in Fig.4showed the same trend as the E p curve.As a matter of fact,the CPT sharply dropped before aging time up to 30min and aging longer than 30min
lowered the CPT slightly.Rapid deterioration of corrosion resistance with aging time was seen,which coincided with the evolution of Cr 2N precipitates.The nucleation and growth of Cr 2N precipitates were governed by the diffusion of Cr atoms and N atoms,respectively [25].The formation of Cr 2N precipitates containing higher concentration of Cr caused localized depletion areas in Cr around the Cr 2N.This Cr-depletion zones became unstable and transformed into secondary austenite (γ2),leading to the decrease of E p and CPT values.The E p and CPT values both settled at a constant value after aging for 120min,revealing that the zones with a maximum depletion of Cr had formed in γ2after this aging time [22].Only an increase in the amount of maximum depleted γ2was expected after further aging.This was confirmed by the larger passivation current density after aging time longer than 120min.In other words,the values of E p and CPT referred to the least resistant locations at the surface of specimens,while the value of passivation current density was connected to the average of surface conditions.However,a difference between these two curves in Fig.4also can be found that the E p varied slightly before aging time of 6min (from 340mV to 310mV)while the CPT dropped greatly (from 34°C to 26°C).The fact that the decrease in pitting potential (E p )lagged behind the drop in CPT during the initial aging seemed to be attributed to slowness of response to critical condition of the potentiodynamic test compared to the potentiostatic CPT measurement.This result was consistent with the finding reported in previous literature [26].In a word,it can be inferred from the results above that the deleterious effect of Cr 2N on pitting corrosion was associated with the formation of Cr-depletion zone adjacent to Cr 2N precipitates and the pitting corrosion resistance was strongly dependent on the amount of precipitates.
Deterioration of the toughness of DSS 2101,due to Cr 2N precipitates,was found to occur before reduction of corrosion resistance in chloride solution.The effect of 700°C aging on the Cr 2N formation and mechanical properties of DSS 2101had been previously reported [21].It was interesting to note that the drop in the impact strength was in contradiction with results found for corrosion resistance in 1mol L ?1NaCl solution.With aging to 15min,the impact energy
was
Fig.3–Curves of current density and temperature for DSS 2101in 1mol L ?1NaCl solution aged at 700°C for different
times.
Fig.4–Critical pitting temperature (CPT)and pitting potential (E p )as a function of aging time.
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negatively shifted to 38J corresponding to a drop of about 68%,which was higher than the decrease of 44%in CPT value under the same aging condition.Thus,it could be concluded that the effect of Cr 2N on the mechanical properties was more severe than that on the corrosion resistance during the initial aging.Before the corrosion resistance of DSS 2101in chloride solution was affected,the material had experienced unac-ceptable change in mechanical properties (toughness).
3.3.Pit Morphology
Surface morphologies of the specimens were investigated after the electrochemical tests.Most of metastable pitting occurred in the ferrite phase and a few nucleated in the ferrite/austenite interface for the solution-annealed specimen,while for the aged specimens,the metastable pitting was seen to initiate around the precipitates and few was also observed in the ferrite phase.Fig.5(a)and (b)shows two kinds of typical metastable pits formed on the annealed-solution and aged for 10min specimens,respectively.The metastable pit with diameter of ~3μm for the annealed-solution specimen was mainly found in the ferrite phase,which had been reported in preliminary work [13].This could be explained with the different chemical compositions between the two phases,namely the pitting resistance equivalent (PRE)of the two phases [27].It has been considered widely that higher PRE means better pitting corrosion resistance.The average com-
position of the main alloying elements in the austenite and ferrite phases in the annealed at 1050°C is shown in Table 2together with the PRE values of the two phases.It indicated that the PRE of ferrite phase (21.03)was lower than that of austenite phase (29.00),resulting in the fact that the ferrite phase became prime sites for pit nucleation.However,PRE can only be used to predict the preferential initiation of pits for solution-annealed materials.The situation became complex when DSS were submitted to welding or heat treatment in temperature ranges where outstanding phase transformation and precipitation of intermetallic phases occurred.Fig.5(b)shows the metastable pit with a diameter of ~5μm formed on the specimen aged at 700°C for 10min.It was found that pit firstly initiated around the precipitates at the α/γboundaries and then propagated obviously into the ferrite phase and repassivated without growing into stable pit,which attributed to the small amount of precipitates.For the aged DSS 2101,the pit initiated around the precipitates,i.e.in the newly formed secondary austenite phase γ2,because γ2had lower Cr content than ferrite phase and austenite phase,resulting in poorer pitting corrosion resistance.
With increasing the aging duration,the amount of precipitates became larger.Fig.6demonstrates the stable pits formed surface of the specimen aged for 240min.It suggested in this figure that pitting was initiated along the α/γboundaries and α/αboundaries and had continued into the ferrite phase.The secondary austenite phases seemed to serve as a path for the corrosive environment to penetrate from
the
Fig.5–SEM morphologies of the corrosion attack on the DSS 2101below the CPT:(a)metastable pit formed on the
solution-annealed specimen,(b)metastable pit formed on the specimen aged for 10min.
Table 2–The chemical composition (wt.%)and PRE of αand γfor DSS 2101in solution-annealed condition.Material
Phase Fe Cr Ni
Mo Mn N a PRE b
DSS 2101
Ferrite 69.3523.040.820.59 5.450.0521.03Austenite 70.6020.95 1.300.47 6.120.4229.00Both phases 69.9922.03 1.050.53 5.770.2324.91
a
Nitrogen in ferrite is taken as the saturation value ≈0.05%,the rest partitions to austenite [28].b
According to the following equation:according to the following equation:PRE =%Cr +3.3%Mo +30%N ?1×
%Mn.
Fig.6–SEM morphologies of the pitting corrosion occurred on the sample aged for 240min above the CPT.
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outer surface to the inside of the specimens.Consequently, the characteristic mechanism of pitting corrosion for aged specimens was the selective dissolution of secondary austen-ite phase,which is consistent with the results reported in previous literature[29].From the corrosion morphology study it can be concluded that the amount of precipitates played an important role in pit initiation and propagation.
4.Conclusions
The aging treatment of lean DSS2101at700°C produced intermetallic precipitates along theα/γandα/αboundaries. These precipitates contained higher chromium content as compared to the ferrite and austenite phases.Adjacent to the precipitates,a low-chromium region called secondary austenite phase was found.The pitting potential(E p)and critical pitting temperature(CPT)dropped drastically before aging time of 30min.The potentiostatic CPT measurement showed more sensitive to the small amount of precipitates compared to the potentiodynamic polarization test.Pit initiation was found to be around the precipitates due to the selective dissolution of the secondary austenite phases.Once initiated,these pits grew into the ferrite phase.After being aged at700°C,DSS2101showed unacceptable change in mechanical properties(embrittlement) before the corrosion resistance in chloride solution was affected.
Acknowledgements
The authors would like to thank Mr.Hu Gang for his great help with SEM analysis.This work was supported by the National Natural Science Foundation of China(grant.No.10621063and 50871031),the Chinese National Science and Technology Infrastructure Platforms Construction Project（Grant.No. 2005DKA10400-Z13）,the Shanghai Science and Technology Development Funds(0725nm004),the China Postdoctoral Science Foundation(No.20080430670)and the Shanghai Leading Academic Discipline Project(No.B113).
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1528M A T E R I A L S C H A R A C T E R I Z A T I O N60(2009)1522–1528
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一般过去式 时间状语：yesterday just now (刚刚) the day before three days ag0 a week ago in 1880 last month last year 1. I was in the classroom yesterday. I was not in the classroom yesterday. Were you in the classroom yesterday. 2. They went to see the film the day before. Did they go to see the film the day before. They did go to see the film the day before. 3. The man beat his wife yesterday. The man didn’t beat his wife yesterday. 4. I was a high student three years ago. 5. She became a teacher in 2009. 6. They began to study english a week ago 7. My mother brought a book from Canada last year. 8.My parents build a house to me four years ago . 9.He was husband ago. She was a cooker last mouth. My father was in the Xinjiang half a year ago. 10.My grandfather was a famer six years ago. 11.He burned in 1991
●I wonder if it’s because I have been at school for so long that I’ve grown so crazy about going home. ●It is because she wasn’t well that she fell far behind her classmates this semester. ●I can well remember that there was a time when I took it for granted that friends should do everything for me. ●In order to make a difference to society, they spent almost all of their spare time in raising money for the charity. ●It’s no pleasure eating at school any longer because the food is not so tasty as that at home. ●He happened to be hit by a new idea when he was walking along the riverbank. ●I wonder if I can cope with stressful situations in life independently. ●It is because I take things for granted that I make so many mistakes. ●The treasure is so rare that a growing number of people are looking for it. ●He picks on the weak mn in order that we may pay attention to him. ●It’s no pleasure being disturbed whena I settle down to my work. ●I can well remember that when I was a child, I always made mistakes on purpose for fun. ●It’s no pleasure accompany her hanging out on the street on such a rainy day. ●I can well remember that there was a time when I threw my whole self into study in order to live up to my parents’ expectation and enter my dream university. ●I can well remember that she stuck with me all the time and helped me regain my confidence during my tough time five years ago. ●It is because he makes it a priority to study that he always gets good grades. ●I wonder if we should abandon this idea because there is no point in doing so. ●I wonder if it was because I ate ice-cream that I had an upset student this morning. ●It is because she refused to die that she became incredibly successful. ●She is so considerate that many of us turn to her for comfort. ●I can well remember that once I underestimated the power of words and hurt my friend. ●He works extremely hard in order to live up to his expectations. ●I happened to see a butterfly settle on the beautiful flower. ●It’s no pleasure making fun of others. ●It was the first time in the new semester that I had burned the midnight oil to study. ●It’s no pleasure taking everything into account when you long to have the relaxing life. ●I wonder if it was because he abandoned himself to despair that he was killed in a car accident when he was driving. ●Jack is always picking on younger children in order to show off his power. ●It is because he always burns the midnight oil that he oversleeps sometimes. ●I happened to find some pictures to do with my grandfather when I was going through the drawer. ●It was because I didn’t dare look at the failure face to face that I failed again. ●I tell my friend that failure is not scary in order that she can rebound from failure. ●I throw my whole self to study in order to pass the final exam. ●It was the first time that I had made a speech in public and enjoyed the thunder of applause. ●Alice happened to be on the street when a UFO landed right in front of her. ●It was the first time that I had kept myself open and talked sincerely with my parents. ●It was a beautiful sunny day. The weather was so comfortable that I settled myself into the
高中英语~词性~句子成分~语法构成 第一章节：英语句子中的词性 1.名词：n. 名词是指事物的名称，在句子中主要作主语.宾语.表语.同位语。 2.形容词;adj. 形容词是指对名词进行修饰~限定~描述~的成份，主要作定语.表语.。形容词在汉语中是（的）.其标志是: ous. Al .ful .ive。. 3.动词：vt. 动词是指主语发出的一个动作，一般用来作谓语。 4.副词：adv. 副词是指表示动作发生的地点. 时间. 条件. 方式. 原因. 目的. 结果.伴随让步. 一般用来修饰动词. 形容词。副词在汉语中是（地）.其标志是：ly。 5.代词：pron. 代词是指用来代替名词的词，名词所能担任的作用，代词也同样.代词主要用来作主语. 宾语. 表语. 同位语。 6.介词：prep.介词是指表示动词和名次关系的词，例如：in on at of about with for to。其特征：
介词后的动词要用—ing形式。介词加代词时，代词要用宾格。例如：give up her（him）这种形式是正确的，而give up she（he）这种形式是错误的。 7.冠词：冠词是指修饰名词，表名词泛指或特指。冠词有a an the 。 8.叹词：叹词表示一种语气。例如：OH. Ya 等 9.连词：连词是指连接两个并列的成分，这两个并列的成分可以是两个词也可以是两个句子。例如：and but or so 。 10.数词：数词是指表示数量关系词，一般分为基数词和序数词 第二章节：英语句子成分 主语：动作的发出者，一般放在动词前或句首。由名词. 代词. 数词. 不定时. 动名词. 或从句充当。 谓语：指主语发出来的动作，只能由动词充当，一般紧跟在主语后面。 宾语：指动作的承受着，一般由代词. 名词. 数词. 不定时. 动名词. 或从句充当. 介词后面的成分也叫介词宾语。 定语：只对名词起限定修饰的成分，一般由形容
M A: Has the case been closed yet? B: No, the magistrate still needs to decide the outcome. magistrate n.地方行政官，地方法官，治安官 A: I am unable to read the small print in the book. B: It seems you need to magnify it. magnify vt.１．放大，扩大；２．夸大，夸张 A: That was a terrible storm. B: Indeed, but it is too early to determine the magnitude of the damage. magnitude n.１．重要性，重大；２．巨大，广大 A: A young fair maiden like you shouldn’t be single. B: That is because I am a young fair independent maiden. maiden n.少女，年轻姑娘，未婚女子 a.首次的，初次的 A: You look majestic sitting on that high chair. B: Yes, I am pretending to be the king! majestic a.雄伟的，壮丽的，庄严的，高贵的 A: Please cook me dinner now. B: Yes, your majesty, I’m at your service. majesty n.１．［Ｍ－］陛下（对帝王，王后的尊称）；２．雄伟，壮丽，庄严 A: Doctor, I traveled to Africa and I think I caught malaria. B: Did you take any medicine as a precaution? malaria n.疟疾 A: I hate you! B: Why are you so full of malice? malice n.恶意，怨恨 A: I’m afraid that the test results have come back and your lump is malignant. B: That means it’s serious, doesn’t it, doctor? malignant a.１．恶性的，致命的；２．恶意的，恶毒的 A: I’m going shopping in the mall this afternoon, want to join me? B: No, thanks, I have plans already. mall n.（由许多商店组成的）购物中心 A: That child looks very unhealthy. B: Yes, he does not have enough to eat. He is suffering from malnutrition.
意见应以事实为根据. 3 来自辞典例句 192. The bombers swooped ( down ) onthe air base. 轰炸机 突袭 空军基地. 来自辞典例句 193. He mounted their engines on a rubber base. 他把他们的发动机装在一个橡胶垫座上. 14 来自辞典例句 194. The column stands on a narrow base. 柱子竖立在狭窄的地基上. 14 来自辞典例句 195. When one stretched it, it looked like grey flakes on the carvas base. 你要是把它摊直, 看上去就象好一些灰色的粉片落在帆布底子上. 18 来自辞典例句 196. Economic growth and human well - being depend on the natural resource base that supports all living systems. 经济增长和人类的福利依赖于支持所有生命系统的自然资源. 12 1 来自辞典例句 197. The base was just a smudge onthe untouched hundred - mile coast of Manila Bay. 那基地只是马尼拉湾一百英里长安然无恙的海岸线上一个硝烟滚滚的污点. 6 来自辞典例句 198. You can't base an operation on the presumption that miracles are going to happen. 你不能把行动计划建筑在可能出现奇迹的假想基础上.
英语造句大全English sentence 在句子中，更好的记忆单词！ 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character. （2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n.
主语+谓语 1. 理解主谓结构 1) The students arrived. The students arrived at the park. 2) They are listening. They are listening to the music. 3) The disaster happened. 2．体会状语的位置 1) Tom always works hard. 2) Sometimes I go to the park at weekends.. 3) The girl cries very often. 4) We seldom come here. The disaster happened to the poor family. 3. 多个状语的排列次序 1) He works. 2) He works hard. 3) He always works hard. 4) He always works hard in the company. 5) He always works hard in the company recently. 6) He always works hard in the company recently because he wants to get promoted. 4. 写作常用不及物动词 1. ache My head aches. I’m aching all over. 2. agree agree with sb. about sth. agree to do sth. 3. apologize to sb. for sth. 4. appear (at the meeting, on the screen) 5. arrive at / in 6. belong to 7. chat with sb. about sth. 8. come (to …) 9. cry 10. dance 11. depend on /upon 12. die 13. fall 14. go to … 15. graduate from 16. … happen 17. laugh 18. listen to... 19. live 20. rise 21. sit 22. smile 23. swim 24. stay (at home / in a hotel) 25. work 26. wait for 汉译英： 1.昨天我去了电影院。 2.我能用英语跟外国人自由交谈。 3.晚上7点我们到达了机场。 4.暑假就要到了。 5.现在很多老人独自居住。 6.老师同意了。 7.刚才发生了一场车祸。 8.课上我们应该认真听讲。9. 我们的态度很重要。 10. 能否成功取决于你的态度。 11. 能取得多大进步取决于你付出多少努力。 12. 这个木桶能盛多少水取决于最短的一块板子的长度。
【it's time to和it's time for】 ——————这其实是一个句型,只不过后面要跟不同的东西. ——————It's time to跟的是不定式（to do）.也就是说,要跟一个动词,意思是“到做某事的时候了”.如： It's time to go home. It's time to tell him the truth. ——————It's time for 跟的是名词.也就是说,不能跟动词.如： It's time for lunch.(没必要说It's time to have lunch) It's time for class.(没必要说It's time to begin the class.) They can't wait to see you Please ask liming to study tonight. Please ask liming not to play computer games tonight. Don’t make/let me to smoke I can hear/see you dance at the stage You had better go to bed early. You had better not watch tv It’s better to go to bed early It’s best to run in the morning I am enjoy running with music. With 表伴随听音乐 I already finish studying You should keep working. You should keep on studying English Keep calm and carry on 保持冷静继续前行二战开始前英国皇家政府制造的海报名字 I have to go on studying I feel like I am flying I have to stop playing computer games and stop to go home now I forget/remember to finish my homework. I forget/remember cleaning the classroom We keep/percent/stop him from eating more chips I prefer orange to apple I prefer to walk rather than run I used to sing when I was young What’s wrong with you There have nothing to do with you I am so busy studying You are too young to na?ve I am so tired that I have to go to bed early
《The Kite Runner》追风筝的人--------------------------------美句摘抄 1.I can still see Hassan up on that tree, sunlight flickering through the leaves on his almost perfectly round face, a face like a Chinese doll chiseled from hardwood: his flat, broad nose and slanting, narrow eyes like bamboo leaves, eyes that looked, depending on the light, gold, green even sapphire 翻译：我依然能记得哈桑坐在树上的样子，阳光穿过叶子，照着他那浑圆的脸庞。他的脸很像木头刻成的中国娃娃，鼻子大而扁平，双眼眯斜如同竹叶，在不同光线下会显现出金色、绿色，甚至是宝石蓝。 E.g.: A shadow of disquiet flickering over his face. 2.Never told that the mirror, like shooting walnuts at the neighbor's dog, was always my idea. 翻译：从来不提镜子、用胡桃射狗其实都是我的鬼主意。E.g.:His secret died with him, for he never told anyone. 3.We would sit across from each other on a pair of high
一、翻译 1. The idea of consciously seeking out a special title was new to me., but not without appeal. 让我自己挑选自己最喜欢的书籍这个有意思的想法真的对我具有吸引力。 2.I was plunged into the aching tragedy of the Holocaust, the extraordinary clash of good, represented by the one decent man, and evil. 我陷入到大屠杀悲剧的痛苦之中，一个体面的人所代表的善与恶的猛烈冲击之中。 3.I was astonished by the the great power a novel could contain. I lacked the vocabulary to translate my feelings into words. 我被这部小说所包含的巨大能量感到震惊。我无法用语言来表达我的感情（心情）。 4，make sth. long to short长话短说 5.I learned that summer that reading was not the innocent(简单的) pastime(消遣) I have assumed it to be., not a breezy, instantly forgettable escape in the hammock(吊床)，( though I’ ve enjoyed many of those too ). I discovered that a book, if it arrives at the right moment, in the proper season, will change the course of all that follows. 那年夏天，我懂得了读书不是我认为的简单的娱乐消遣，也不只是躺在吊床上，一阵风吹过就忘记的消遣。我发现如果在适宜的时间、合适的季节读一本书的话，他将能改变一个人以后的人生道路。 二、词组造句 1. on purpose 特意，故意 This is especially true here, and it was ~. (这一点在这里尤其准确，并且他是故意的) 2.think up 虚构，编造，想出 She has thought up a good idea. 她想出了一个好的主意。 His story was thought up. 他的故事是编出来的。 3. in the meantime 与此同时 助记：in advance 事前in the meantime 与此同时in place 适当地... In the meantime, what can you do? 在这期间您能做什么呢？ In the meantime, we may not know how it works, but we know that it works. 在此期间，我们不知道它是如何工作的，但我们知道，它的确在发挥作用。 4.as though 好像，仿佛 It sounds as though you enjoyed Great wall. 这听起来好像你喜欢长城。 5. plunge into 使陷入 He plunged the room into darkness by switching off the light. 他把灯一关，房
The effective sentences:(improve the sentences!) 1.She hopes to spend this holiday either in Shanghai or in Suzhou. 2.Showing/to show sincerity and to keep/keeping promises are the basic requirements of a real friend. 3.I want to know the space of this house and when it was built. I want to know how big this house is and when it was built. I want to know the space of this house and the building time of the house. 4.In the past ten years,Mr.Smith has been a waiter,a tour guide,and taught English. In the past ten years,Mr.Smith has been a waiter,a tour guide,and an English teacher. 5.They are sweeping the floor wearing masks. They are sweeping the floor by wearing masks. wearing masks,They are sweeping the floor. 6.the drivers are told to drive carefully on the radio. the drivers are told on the radio to drive carefully 7.I almost spent two hours on this exercises. I spent almost two hours on this exercises. 8.Checking carefully,a serious mistake was found in the design. Checking carefully,I found a serious mistake in the design.
M1 U1 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： add up (to) be concerned about go through set down a series of on purpose in order to according to get along with fall in love (with) join in have got to hide away face to face 1 We’ve chatted online for some time but we have never met ___________. 2 It is nearly 11 o’clock yet he is not back. His mother ____________ him. 3 The Lius ___________ hard times before liberation. 4 ____________ get a good mark I worked very hard before the exam. 5 I think the window was broken ___________ by someone. 6 You should ___________ the language points on the blackboard. They are useful. 7 They met at Tom’s party and later on ____________ with each other. 8 You can find ____________ English reading materials in the school library. 9 I am easy to be with and _____________my classmates pretty well. 10 They __________ in a small village so that they might not be found. 11 Which of the following statements is not right ____________ the above passage? 12 It’s getting dark. I ___________ be off now. 13 More than 1,000 workers ___________ the general strike last week. 14 All her earnings _____________ about 3,000 yuan per month. 二.用以下短语造句： 1.go through 2. no longer/ not… any longer 3. on purpose 4. calm… down 5. happen to 6. set down 7. wonder if 三. 翻译： 1.曾经有段时间，我对学习丧失了兴趣。（there was a time when…） 2. 这是我第一次和她交流。（It is/was the first time that …注意时态） 3.他昨天公园里遇到的是他的一个老朋友。（强调句） 4. 他是在知道真相之后才意识到错怪女儿了。（强调句） M 1 U 2 一. 把下列短语填入每个句子的空白处（注意所填短语的形式变化）： play a …role (in) because of come up such as even if play a …part (in) 1 Dujiangyan(都江堰) is still ___________in irrigation(灌溉) today. 2 That question ___________ at yesterday’s meeting. 3 Karl Marx could speak a few foreign languages, _________Russian and English. 4 You must ask for leave first __________ you have something very important. 5 The media _________ major ________ in influencing people’s opinion s. 6 _________ years of hard work she looked like a woman in her fifties. 二.用以下短语造句： 1.make (good/full) use of 2. play a(n) important role in 3. even if 4. believe it or not 5. such as 6. because of
English sentence 1、(1)、able adj. 能 句子：We are able to live under the sea in the future. (2)、ability n. 能力 句子：Most school care for children of different abilities. (3)、enable v. 使。。。能 句子：This pass enables me to travel half-price on trains. 2、(1)、accurate adj. 精确的 句子：We must have the accurate calculation. (2)、accurately adv. 精确地 句子：His calculation is accurately. 3、(1)、act v. 扮演 句子：He act the interesting character.（2）、actor n. 演员 句子：He was a famous actor. (3)、actress n. 女演员 句子：She was a famous actress. (4)、active adj. 积极的 句子：He is an active boy. 4、add v. 加 句子：He adds a little sugar in the milk. 5、advantage n. 优势 句子：His advantage is fight. 6、age 年龄n. 句子：His age is 15. 7、amusing 娱人的adj. 句子：This story is amusing. 8、angry 生气的adj. 句子：He is angry. 9、America 美国n. 句子：He is in America. 10、appear 出现v. He appears in this place. 11. artist 艺术家n. He is an artist. 12. attract 吸引 He attracts the dog. 13. Australia 澳大利亚 He is in Australia. 14.base 基地 She is in the base now. 15.basket 篮子 His basket is nice. 16.beautiful 美丽的 She is very beautiful. 17.begin 开始 He begins writing. 18.black 黑色的 He is black. 19.bright 明亮的 His eyes are bright. 20.good 好的 He is good at basketball. 21.British 英国人 He is British. 22.building 建造物 The building is highest in this city 23.busy 忙的 He is busy now. 24.calculate 计算 He calculates this test well. 25.Canada 加拿大 He borns in Canada. 26.care 照顾 He cared she yesterday. 27.certain 无疑的 They are certain to succeed. 28.change 改变 He changes the system. 29.chemical 化学药品