形变模式对3104铝合金板微取向流变行为的影响

探讨了不同形变模式(同步轧制、异步轧制和双向异步轧制)对3104铝合金板微取向流变的影响.对各主要冷轧织构组分:Brass({110}〈112〉)、S({123}〈634〉)、R/S({124}〈211〉)、Goss({110}〈001〉)和Copper({112}〈111〉),在三维取向空间的取向密度ω(g)沿板厚的分布进行了定量测定.结果表明:同步轧制时,各层织构组分取向密度呈对称分布;异步轧制与双向异步轧制时,各织构组分与传统的同步轧制的织构组分相同,只是表层各织构组分的强度级别明显提高,沿着轧板的厚度方向呈非对称分布;双向异步轧制下,除各层的织构组分取向密度略有变化外,基本与异步轧制相同.这种巨大的差异,主要是由于异步轧制时,搓轧区剪切应力的大小和方向不同,造成金属微取向流变行为的差异所致.     

同步、异步组合轧制取向硅钢极薄带的织构研究

采用同步、异步组合轧制方式将成品工业取向硅钢板冷轧到0.08mm,然后在纯氢气炉中高温退火,采用ODF和反极图定量分析硅钢薄带的冷轧和再结晶织构。研究结果表明,在同步、异步组合轧制方式下,冷轧薄带的变形织构与一般常规冷轧板的相同,但沿板厚呈现了不对称分布,经840℃保温6h退火,晶粒取向为集中的{110}〈001〉。     

异步累积叠轧纯铜材的取向变化过程与力学性能EI北大核心CSCD

室温下对纯铜薄板进行一到六道次的异步累积叠轧变形加工。采用金相显微镜、扫描电镜附带背散射电子衍射、X射线衍射仪附带织构附件及拉伸试验机进行组织、取向观察及力学性能测试,获得铜材异步叠轧过程的显微组织、轧制织构变化过程和力学性能。结果表明:经过六道次的异步累积叠轧变形,由于压缩变形与剪切变形作用,使晶粒细化,铜材晶粒尺寸由30～50μm细化到5μm。异步叠轧过程中出现:{112}〈111〉,{123}〈634〉,{011}〈211〉和{011}〈100〉几种主要组分轧制织构。材料的屈服强度与抗拉强度明显提高,六道次后分别达到348MPa和452MPa。材料的伸长率在二道次后显著下降到2.3%,然后随等效应变的增加略微下降。     

异步累积叠轧纯铜材的取向变化过程与力学性能

室温下对纯铜薄板进行一到六道次的异步累积叠轧变形加工。采用金相显微镜、扫描电镜附带背散射电子衍射、X射线衍射仪附带织构附件及拉伸试验机进行组织、取向观察及力学性能测试,获得铜材异步叠轧过程的显微组织、轧制织构变化过程和力学性能。结果表明:经过六道次的异步累积叠轧变形,由于压缩变形与剪切变形作用,使晶粒细化,铜材晶粒尺寸由30～50μm细化到5μm。异步叠轧过程中出现:{112}〈111〉,{123}〈634〉,{011}〈211〉和{011}〈100〉几种主要组分轧制织构。材料的屈服强度与抗拉强度明显提高,六道次后分别达到348MPa和452MPa。材料的伸长率在二道次后显著下降到2.3%,然后随等效应变的增加略微下降。     

冷轧形变量对异步轧制高纯铝箔织构的影响

应用取向分布函数(ODF)研究和分析了异步轧制高纯铝箔的形变织构和再结晶织构.结果表明:异步轧制高纯铝箔的形变织构除了C{112}<111>、B{110}<112>和S{123}<634>织构组分外,还有较强的CubeND{001}<110>和{102}织构.异步轧制高纯铝箔的再结晶织构由强的立方织构{001}<100>和弱的R{124}<211>织构组成.随着形变量的增加,异步轧制高纯铝箔的形变织构和再结晶织构呈现规律性的变化,{102}织构减少,S织构先增后减,速比较小时C织构近线性减少,速比较大时C织构则先增后减.异步轧制高纯铝箔的退火样品中有很强的立方织构,这与异步轧制提高高纯铝箔的形变储能有关,形变量过大时,立方织构随形变量的增加急剧减少.{102}织构有利于再结晶立方织构的加强.     

时效工艺对6061铝合金力学性能各向异性的影响及微观组织研究

采用单向拉伸试验研究了经不同时效工艺处理的6061铝合金轧制板材在轧制方向(0°)、倾斜方向(45°)和横向(90°)的力学性能各向异性.实验结果表明,轧制态6061铝合金的力学性能与热处理工艺密切相关,且表现出明显的各向异性.其中T6态6061铝合金力学性能各向异性最不明显.轧制态6061-T6铝合金有较强的立方织构{001}〈100〉和较弱的织构成分{001}〈100〉,目前采用的人工时效方法对其晶粒的显微组织和织构演化的影响不大.相对于经其他工艺处理的轧制态6061铝合金,经240℃高温时效处理的轧制态6061-T6铝合金位错密度大,且分布更均匀.轧制态6061-T6铝合金中明显的高密度β″析出物是其具备最高强度和最低各向异性的主要原因.     

超低碳、氮Cr17铁素体不锈钢低温轧制工艺中织构演变

研究了铁素体不锈钢在低温轧制过程中织构演变及γ纤维再结晶织构的形成机制。结果表明：1.冷轧退火板厚度方向各层织构特征存在显著差异,这主要是由于低温轧制过程中沿板厚方向不同应变状态导致的热轧织构悌度的遗传;2.热轧及退火后,表层织构以剪切织构组分为主,冷轧后得到主要组分集中在{112}〈110〉和{111}〈110〉的冷...     

GH4169合金楔横轧加工过程中动态再结晶及织构演变

为研究GH4169合金楔横轧加工过程中动态再结晶及织构演变规律,采用金相显微镜(OM)和电子背散射衍射(EBSD)对30%,50%两种断面收缩率下GH4169合金楔横轧件表层与心部的微观组织、晶体取向及织构进行分析。结果表明:GH4169合金楔横轧加工过程中,随着动态再结晶的发生,晶体取向逐渐变得随机化分布;轧制表层大角度晶界数量较轧件心部多,轧件表层织构强度变化不大,心部织构强度明显增强;经过楔横轧变形后织构发生转动,原始态织构类型为{001}〈110〉,{111}〈110〉,{111}〈011〉,轧制后主要织构类型为{001}〈010〉,{112}〈110〉,{110}〈111〉,{110}〈112〉;GH4169合金楔横轧件动态再结晶及织构演变规律是由楔横轧特殊变形特点决定的。     

轧制工艺对深冲钼带组织和性能的影响

通过轧制温度、轧制方式实验,以及织构和力学性能分析,研究了轧制工艺对液晶显示背光源用的深冲钼带的组织和性能的影响.结果表明:采用低温开坯,然后低温两次交叉轧制,再进行一次交叉轧制的工艺,使钼带在1 000℃退火后具有很强的{001}〈011〉板织构和弱的〈111〉丝织构;钼带纵、横向组织几乎完全一致,都为细小均匀、相互搭接的纤维状组织;钼带经过消除应力退火后,纵、横向不仅都具有较高并相近的延伸率,而且强度也相近,杯突值较高.由于强度和硬度适中,各项性能形成了很好的匹配,使钼带各向异性大大减弱,深冲性能良好.     

典型特殊制备技术对无取向电工钢织构的影响规律

电工钢又称硅钢,是一种重要的特殊钢,常被称作特殊钢中的“艺术品”,这主要是因为其加工制备流程复杂、性能影响因素繁多。其中无取向硅钢主要应用于旋转电磁场环境,为了获得优良的软磁性能,需要形成较多的{100}等有利织构,为此研究人员进行了大量探索,近年来发现一些特殊制备技术在形成大量{100}等有利织构方面有显著效果。本文综述二次轧制、斜轧、异步轧制及双辊薄带连铸四种典型特殊制备技术对无取向硅钢再结晶织构的影响规律,发现二次轧制与双辊薄带连铸均能增强λ与高斯织构,并削弱γ织构,斜轧也会增强λ织构,但对γ织构影响不大,异速异步轧制能增强η织构,而异径异步轧制对再结晶织构却基本没有影响。最后,总结目前各项特殊制备技术存在的缺陷,并提出一些发展方向,如借助斜轧原理在常规冷轧中产生更多剪切带、利用异步轧制进行二次加工以均匀化磁感等,为后续无取向硅钢的工业生产提供更多参考。     

Al-Zn-Mg-Cu系铝合金厚板冷轧过程中的织构演变

利用电子背散射衍射技术研究了Al-Zn-Mg-Cu系铝合金厚板冷轧过程中不同厚度处的织构演变.结果表明:厚板近表面处的剪切型织构{001}<110>,随着冷轧变形量的增加逐渐向轧制型织构Bs,S,Cu组分转变;厚板1/4厚度和中心厚度处的轧制型织构Bs,S,Cu组分,随着冷轧变形量的增加逐渐流向剪切型织构{001}<1...     

加磷高强Ti-IF钢的最优卷取温度和冷轧压下率的确定

以工业生产的加磷高强Ti-IF钢为试验材料,在实验室研究了卷取温度和冷轧压下率对试验钢显微组织、力学性能和织构的影响.结果表明:在试验条件下,试验钢在不同冷轧压下率下,卷取温度在550～600℃时,再结晶完成;不同卷取温度下,随着冷轧压下率的增加,晶粒变得细小均匀;卷取温度在600℃时,不同冷轧压下率下的屈服强度、抗拉...     

Textural Characteristic of 70-30 Brass Rolled by Cross Shear Rolling in Single Direction

70-30 brass is rolled with 90% reduction bycross shear rolling in single direction with speed ra-tio 1.39.The sheet is divided into five layers alongrolling plane normal to measure macroscopic statis-tical unsymmetric textures in every layer are des-cribed and analysed by means of three dimensionalorientation distribution function.The results indi-cate that the main textures in every layer of brassrolled by cross shear rolling in single direction arethe same as the main textures of brass rolled byconventional rolling.But the intensities,peak posi-tions and scatters of every texture component in{110}<112>are different,namely,there is amacroscopic statistical unsymmetry.It is found thatthe textures in every layer of brass rolled by crossshear rolling in single direction can be considered asthe textures of brass rolled by common rolling insingle direction at identical shear forces,themacroscopic statistical unsymmetry depends on theshear forces which are exerted on the layer.     

循环道次对高温叠轧AZ31镁合金板材组织与性能的影响

目的通过高温累积叠轧工艺制备出高强度的镁合金,并研究该过程中循环道次对AZ31镁合金板材的微观组织与性能的具体影响。方法对累积叠轧1～5次板材进行微观组织观察,并进行显微硬度的测试,得到不同板材的硬度值,通过X射线衍射分析得到不同板材的取向结果,最终进行力学性能实验,并对比分析。结果随着循环道次的增加,板材抗拉强度有明显改变。从260 MPa先增加至310 MPa,最后稳定在350 MPa左右;非基面织构比重增加;断裂伸长率先降低后升高并稳定在10%左右。结论累积叠轧工艺使得AZ31镁合金板材产生了加工硬化,并显著细化了晶粒。循环道次的增加、孪晶产生和晶界数量显著增多导致强度进一步提高。     

Effect of Coiling Temperature on the Evolution of Texture in Ferritic Rolled Ti-IF Steel

The effect of coiling temperatures on the evolution of texture in Ti-IF steel during ferritic hot rolling, cold rolling and annealing was studied. It was found that texture evolution at high temperature coiling is absolutely different from that at low temperature one. The hot band texture includes a strong α-fiber as well as a weak γ-fiber after ferritic hot rolling and low temperature coiling. Both of them intensify after cold rolling and a γ-fiber with peak at {111}〈112〉 is the main texture of annealed samples. However, the main component of the hot band texture after high temperature coiling is v-fiber. After cold rolling, the intensity of γ texture reduces; α fiber （except {111}〈110〉 component） intensifies and a strong and well-proportioned γ-fiber forms in the annealed samples.     

Influence of Widening on the Rolling and Recrystallization Texture in High Purity Al with Initial Cube Texture

The influence of widening and initial Cube tex-ture on formation of rolling and recrystallizationtexture was investigated in high purity Al.With in-creasing widening the initial Cube texture has ro-tated more around rolling direction(RD)and lessaround transverse direction(TD).Therefore,moreorientations rotate in x-fibre between G{110}<001>and B{110}<112>positions,and less inS{124}<211>texture component,which showsthe widening plays an important role in the forma-tion of S component during rolling.The relation-ship between rolling and recrystallization texturecomponents is discussed.Though the transitionband predicted by Dillamore and Katoh is alwaysformed during rolling,the most important factor in-fluencing recrystallization texture should be the ori-ented growth according to the changes of volumefractions and scatter widths of texture componentswith widening.     

Dynamic deformation behavior and microstructural evolution during high-speed rolling of Mg alloy having non-basal texture

The dynamic deformation behaviors and resultant microstructural variations during high-speed rolling(HSR) of a Mg alloy with a non-basal texture are investigated. To this end, AZ31 alloy samples in which the basal poles of most grains are predominantly aligned parallel to the transverse direction(TD) are subjected to hot rolling with different reductions at a rolling speed of 470 m/min. The initial grains with a TD texture are favorable for {10–12} twinning under compression along the normal direction(ND); as a result, {10–12} twins are extensively formed in the material during HSR, and this consequently results in a drastic evolution of texture from the TD texture to the ND texture and a reduction in the grain size. After the initial grains are completely twinned by the {10–12} twinning mechanism, {10–11} contraction twins and {10–11}-{10–12} double twins are formed in the {10–12} twinned grains by further deformation.Since the contraction twins and double twins have crystallographic orientations that are favorable for basal slip during HSR, dislocations easily accumulate in these twins and fine recrystallized grains nucleate in the twins to reduce the increased internal strain energy. Until a rolling reduction of 20%, {10–12}twinning is the main mechanism governing the microstructural change during HSR, and subsequently,the microstructural evolution is dominated by the formation of contraction twins and double twins and the dynamic recrystallization in these twins. With an increase in the rolling reduction, the average grain size and internal strain energy of the high-speed-rolled(HSRed) samples decrease and the basal texture evolves from the TD texture to the ND texture more effectively. As a result, the 80% HSRed sample, which is subjected to a large strain at a high strain rate in a single rolling pass, exhibits a fully recrystallized microstructure consisting of equiaxed fine grains and has an ND basal texture without a TD texture component.     

铸态AZ31镁合金板材等温轧制工艺及组织性能研究

为研究铸态AZ31镁合金轧制工艺及轧制后组织性能,通过试验得到不同道次和变形量对铸态AZ31镁合金板材显微组织和力学性能的影响规律,并采用扫描电子显微镜研究了轧制后板材组织.结果表明,铸态AZ31镁合金板材经等温4道次、等变形量轧制后,板材厚度由20mm变化到4.8 mm,抗拉强度和屈服强度分别达到275 MPa和18...     

Recrystallisation textures in cold rolled low carbon steel containing ferritic and bainitic microstructures

Abstract

Low carbon steel strip was heat treated to generate four different starting microstructures (fine and coarse polygonal ferrite, acicular ferrite and bainite) for investigating their influence on texture development during cold rolling and annealing. The starting materials were cold rolled to 50–90% reduction and annealed for various times in the temperature range 853–953 K. The resultant microstructures and textures were examined mainly by electron backscatter diffraction and X-ray diffraction. The initial microstructure strongly influenced the crystallographic rotation paths during cold rolling, whereby high strain deformation generated strong {223}〈110〉 texture components in the polygonal ferritic microstructures, whereas a strong {001}〈110〉 texture was produced in the acicular/bainitic microstructures. Subsequent annealing generated, to varying degrees, the classic {111}〈uvw〉 (γ-fibre) recrystallisation texture in all materials. Unexpectedly, coarse polygonal ferrite produced the strongest γ-fibre recrystallisation texture after 70–90% cold rolling reduction. Based on arguments involving the effect of carbon in solution, initial grain size and deformation textures on recrystallisation texture development, it was shown that a strong γ-fibre texture can indeed be generated in coarse polygonal ferrite.