柱状晶Ni在冷轧过程中晶粒取向的演变及模拟

将具有{001)取向的柱状晶Ni样品分别冷轧到0％,10％,30％和50％,用电子背散射图(EBSP)技术测量晶粒取向,跟踪晶粒取向在轧制过程中的演变,得到晶粒取向演变的统计性结果.采用Taylor模型模拟晶粒取向的演变,并与实验结果比较.结果表明,晶粒取向的演变主要受原取向的影响,只有一部分晶粒取向的演变符合Taylor模型.     

针状铁素体管线钢的低温韧性与“有效晶粒尺寸”的新定义

研究了试验钢的系列温度夏比冲击和落锤撕裂(DWTT)韧性性能,统计了沿解理裂纹扩展方向上的各种微观结构晶界的位向差角,计算了5个不同轧制方向上(0°、30°、45°、60°和90°)解理裂纹扩展路径上{100}解理面的夹角,重新定义了高等级针状铁素体试验钢的有效晶粒尺寸(晶界位相差大于15°),并定量分析了重新定义的有效晶粒尺寸和低温韧性性能(夏比冲击和DWTT)的关系。结果表明,不同方向上试验钢的微观组织相同,都是典型的针状铁素体(AF)+多边形铁素体(QF)+M/A岛。不同方向上大角度晶界都主要分布在45°~65°区间范围内。随着重新定义的有效晶粒尺寸(晶界间{100}解理面小于35°的晶粒组成的解理单元)的细化,5个方向的冲击吸收能量(ASTM A370-2017)和DWTT撕裂剪切面积均增大,而韧脆转变温度也随之降低。重新定义的有效晶粒晶界可以强烈阻碍解理断裂扩展,是断裂裂纹解理的有效组织单元。     

柱状晶对Fe-3%Si电工钢冷轧织构演变规律的影响

Fe-3%Si电工钢铸锭中普遍存在柱状晶,其晶体学及形状各向异性对随后的热轧、冷轧及退火织构产生很大的影响.利用xRD与EBSD技术对长轴分别平行于轧面法向(ND),轧制方向(RD)和横向(TD)的柱状晶冷轧样品的织构及组织进行了研究,并对晶界的特殊作用进行了分析.结果表明,中等压下量下,3种柱状晶样品具有不同程度的{001}织构遗传性,即3种样品均不同程度的摆脱了{111}线织构的形成;柱状晶长轴平行于ND和TD时,{001}取向在冷轧时得到大的保留;柱状晶长轴平行于RD时,得到最强的{111}〈112〉织构;柱状晶长轴平行于TD时,冷轧组织中旋转立方织构及{111}〈110〉织构较强.此外,3种样品的织构均表现出由立方→{001}〈130〉→{113}〈251〉的过渡路径,与等轴多晶样品沿α线和γ线转动的路径不同.不同方向的柱状晶晶界对冷轧变形过程中晶粒转动的作用不同,但因晶粒尺寸大而作用有限,且与初始取向相关.     

不同晶粒尺寸5083铝合金晶间腐蚀和应力腐蚀开裂的差异性

通过冷轧和退火获得具有不同晶粒尺寸(8.7～79.2μm)的5083铝合金板.研究其微观结构、晶间腐蚀(IGC)、应力腐蚀开裂(SCC)和裂纹扩展行为.结果表明,粗晶粒样品表现出更好的抗IGC性能,其腐蚀深度为15μm.慢应变速率测试结果表明,细晶粒样品表现出更好的抗SCC性能,敏感性指数ISSRT为11.2％.此外,...     

Final thickness reduction and development of Goss texture in C- and Al-free Fe-3%Si-0.1%Mn-0.012%S electrical steel

The correlation between final thickness reduction and development of Goss texture has been investigated in a C- and Al-free Fe-3%Si electrical steel. During final annealing, the annealing texture is transited from {110}⊥ND to {100}⊥ND texture with increasing final thickness reduction. This is due to the decrease in primary grain size after pre-annealing with increasing final thickness reduction which accelerates the selective growth rate of the {100} grains at the expense of the other {hkl} grains. At an optimal final thickness reduction of 75.8%, the high magnetic induction of 1.95 Tesla, which arises from the sharp {110}<001> Goss texture and is comparable to that of conventional grain-oriented electrical steels, is obtained from the C- and Al-free Fe-3%Si-0.1%Mn electrical steel. Such a high magnetic property is produced through the surface-energy-induced selective grain growth of the Goss grains under the lower surface-segregated condition of sulfur which makes the surface energy of the {110} plane lowest among the {hkl} planes.     

铁素体轧制对普通用冷轧钢板组织和性能的影响

采用光学显微镜和扫描电镜对比研究了铁素体区热轧工艺及奥氏体区热轧工艺对普通用冷轧钢板(SPCC)产品热轧组织、冷轧组织及性能的影响。结果表明,与奥氏体区轧制工艺相比,采用铁素体区热轧工艺生产的SPCC热轧板晶粒尺寸会增大约17 μm,{111}面织构数量减少了8.74%,强度略微降低,而{001}<110>织构数量增加了12.40%,强度提高了19.81。此外,采用铁素体区热轧工艺生产的SPCC成品晶粒呈近似等轴状,与奥氏体区热轧工艺相比平均晶粒尺寸增大了4.5 μm。SPCC铁素体区轧制热轧板中更大的晶粒尺寸、更少的{111}面织构及更强的{001}<110>取向织构导致了冷轧成品更低的屈服强度和塑性应变比r值,较奥氏体区热轧工艺而言平均屈服强度降低了19 MPa,平均r值下降了1.1。     

Effect of the reduction ratio per pass on the microstructure of a hot-rolled AZ31 magnesium alloy sheet

The effect of the reduction ratio per pass on the microstructural evolution of an AZ31 gravity cast plate during hot rolling was evaluated systematically. {10$ \bar 1 $ \bar 1 2} extension twinning was observed in large grains after an earlier rolling pass, but it disappeared upon a subsequent rolling pass due to the reorientation of the grains in an unfavorable direction caused by repetitive rolling. The finer grains were newly formed at the boundaries of the original large grains and twin boundaries by dynamic recrystallization. The grain size distribution was changed from a bimodal distribution upon a small total reduction to a homogeneous distribution upon a large total reduction due to the formation of finer grains that continued at the grain boundaries of large grains by repetitive hot rolling. The size and distribution of the grains were affected not only by the reduction ratio per pass but also by the total reduction (number of rolling passes).     

一种5083铝合金中晶界面热轧织构的研究

通过电子背散射衍射技术,测定了一种5083铝合金中的热轧织构。结果表明：在结构中的不同位置,织构组分呈现非均匀发展的特点,特别地,晶界面亦呈现取向织构。在样品的中心位置,晶界面趋向于{111}取向,且其数量高出随机晶界50%;同时,在样品的边缘位置,晶界面趋向于{110}与{112} 取向,且其数量高出随机晶界28%。更具体地,小角和大角晶界中均呈现这种晶界面的各向异性分布。     

HYDROGEN INDUCED CRACKING IN FERRITICAUSTENITIC DUPLEX STAINLESS STEEL

Hydrogen induced cracking in a ferritic-austenitic duplex stainless steel has been investigatedusing compact tension tests.The stress intensity threshold K_H of the steel rises with increasingaustenite content and decreases with increasing current density during hydrogen charging.Thehydrogen induced cracking initiates and propagates on {100} planes of the ferrite grains.Theaustenite grains play a “fibre-toughened” role during obstructing crack propagation.     

表面机械研磨处理的IF钢结构、织构与力学性能的变化

对冷轧IF钢进行表面机械研磨处理,获得表面为纳米晶、晶粒尺寸沿厚度方向逐渐增大的梯度结构,对梯度结构进行织构分析和性能测试.结果表明:冷轧IF钢的表面纳米化主要是通过位错运动实现的,织构对纳米化方式并不构成影响;在晶粒细化和取向差逐渐增大的过程中,织构组分不变,但强度下降,直至完全消失;冷轧IF钢纳米化的速率与轧面织构有关,具有{100}或{111}面织构的晶粒更容易细化;表面纳米化使IF钢板材的强度、延伸率和成形性均有所提高.     

Microstructure Evolution and Hardness of an Ultra-High Strength Cu-Ni-Si Alloy During Thermo-mechanical Processing

Microstructure evolution and hardness changes of an ultra-high strength Cu-Ni-Si alloy during thermo-mechanical processing have been investigated. For hot-compressive deformation specimens, dynamic recrystallization preferentially appeared on deformation bands. As deformation temperature increased from 750 to 900 °C, elongated grains with the Cubic texture {001} 〈100〉 were substituted by recrystallized grains with Copper texture {112} 〈111〉. For the samples having undergone cold rolling followed by annealing, static recrystallization preferentially occurred in the deformation bands, and then complete recrystallization occurred. Goss, Cubic, and Brass textures remained after annealing at 600 and 700 °C for 1 h; R texture {111} 〈211〉 and recrystallization texture {001} 〈100〉 were formed in samples annealed at 800 and 900 °C for 1 h, respectively. For samples processed under multi-directional forging at cryogenic temperature, the hardness was increased as a result of work hardening and grain refinement strengthening. These were attributed to the formation of equiaxed sub-grain structures and a high dislocation density.     

Effect of the hot-rolling microstructure on texture and surface roughening of Al-Mg-Si series aluminum alloy sheets

This study investigates the effect of microstructural changes induced by hot rolling on the formation of the texture in high-strength aluminum alloy sheets used in automotive applications. Fully (S2) and partially (S1) re-crystallized samples were fabricated by controlling the final hot-rolling temperature. Optical microscopy (OM) was used to observe the microstructure of the transverse direction (TD)-plane of the hot-rolled strips, and the electron back-scattered diffraction (EBSD) technique was used to evaluate the texture of the normal direction (ND)-plane of the finished sheets that were subjected to hot rolling, followed by cold rolling and a solid-solution heat treatment (SSHT). The grains in S1 showed a low-angle grain boundary, and the concentrations of Cube {001}〈100〉 and Goss {011}〈100〉 orientations were detected at different sheet thicknesses. In contrast, a randomized texture was observed in S2. On the basis of the above results, this paper discusses how the microstructure and texture achieved after hot rolling can influence the final microstructure, texture and surface roughening behavior.     

STUDY ON FRACTOGRAPHY OF TRANSGRANULAR SCC OF 70Cu-3OZn IN AN AMMONIACAL SOLUTION

1.IntroductionThemechanismsofstresscorrosioncracking(SCC)havenotyetbeenresolved,andthisproblemremainsasignificalltengineeringconcernandisofacademicillterest.Ofparticularinterestisthecaseoftransgranularstresscorrosioncracking(TSCC)oftheductileface-centeredcubic(FCC)metalsandalloyssincethesematerialshavemultipleslipsystemsandarecharacterizedbyhighdislocationvelocities.SinceSCCisacrackingphenomenon,thepropagationmechanismsmustbeabletofullyexplainthedetailsonthefracturesurfacesproducedbyanddu…     

Correlating oriented grain number density of recrystallisation in particle-containing aluminium alloys

The recrystallized grain structure of Al–(Mn)–Fe–Si alloys after isothermal annealing was studied by electron backscatter diffraction (EBSD) technique. Statistical correlation suggests that the frequency of forming P-oriented ({011}«566») grains at a particle larger than the critical diameter (about 1.1 μm) is about 2% when the effect of fine dispersoids and concurrent precipitation is negligible. The overall grain number density is correlated linearly with the number densities of P and Cube ({001}«100») grains. The grain number densities of typical orientations (P, ND-rotated cube {001}«310» and Cube) and the overall recrystallized grains increase as rolling strain increases, following a similar exponential law.     

中低应变量冷轧AA1050铝合金中晶粒取向与形变位错界面的演变

采用ECC和EBSD技术研究了AA1050铝合金冷轧至中低应变量下位错界面结构的演变. 结果表明, 冷轧至中低应变量下形成典 型的位错胞块结构,其微观组织结构强烈依赖于晶粒的取向. 变形后主要形成三种典型的组织结构: Type A------两组交叉的几何必须位错界面 (GNBs) 结构,Type B------一组GNBs结构, Type C------近似等轴的普通胞状结构. 绝大多数Copper, Brass和Goss取向的晶粒具有Type A结构, S取向的晶粒具有Type B结构, 而Cube取向的晶粒主要具有Type C结构. 变形过程中的GNBs不仅具有与RD成±(30°---40°) 的宏观取向, 而且大多数GNBs位错界面近似平行于由最大Schmid因子所确定的{111}滑移面的迹线.     

冷轧变形量对Al-Mg-Si合金织构的影响

利用光学显微镜、扫描电镜分析了不同冷轧变形量对Al-Mg-Si合金显微组织和微观织构的影响。结果表明:随着变形量的增加,再结晶织构Cube{001}<100>会经由Goss{011}<100>逐渐演变为以Copper{112}<111>和S{123}<634>为主要取向的形变织构,而Goss{011}<100>的体积分数表现为先增大后减小的趋势;合金形变带织构主要由强度较高的Copper{112}<111>织构和强度较弱的Cube{001}<100>织构组成;当变形量小于20%时,晶粒主要取向为{001}、{012},变形量大于40%时,{011}、{112}、{123}成为主要的晶粒取向。     

Relationships between deformation mechanisms and initial textures in polycrystalline magnesium alloys AZ31

1　INTRODUCTIONMagnesiumisthelightestmetallicstructuralma terialwithhighspecificstrengthandisusedinauto motive ,electronicsandaerospacefield[1,2 ] .Howev er ,magnesiumoftenshowspoorformabilityatroomtemperatureduetoitshexagonalstructurewithlessindependentslipsystems ,whichlimitsitsuse .Dif ferentslipsystemshavebeendetectedinmagnesiumsuchasbasalslipof { 0 0 0 1}〈112 0〉 ,prismslipof{ 10 10 }〈112 0〉[3,4 ] andpyramidslip (includingthea typeof {hkil}〈112 0〉andthea +ctypeof {hkil}〈112 3〉[…     

Recrystallized microstructural evolution of UFG copper prepared by asymmetrical accumulative rolling-bonding process

Copper sheet with grain size of 30-60μm was processed by plastic deformation of asymmetrical accumulative rolling-bonding(AARB)with the strain of 3.2.The effects of annealing temperature and time on microstructural evolution were studied by means of electron backscattered diffraction(EBSD).EBSD grain mapping,recrystallization pole figure and grain boundary misorientation angle distribution graph were constructed,and the characteristics were assessed by microstructure,grain size,grain boundary misorientation and texture.The results show that ultra fine grains(UFG)are obtained after annealing at 250℃ for 30?40 min.When the annealing is controlled at 250℃for 40 min,the recrystallization is finished,a large number of small grains appear and most grain boundaries consist of low-angle boundaries.The character of texture is rolling texture after the recrystallization treatment,but the strength of the texture is faint.While second recrystallization happens,{110}1ī2+{112}11ī texture component disappears and turns into{122}212cube twin texture component.     

The Effect of Texture on the Corrosion Behavior of AZ31?Mg Alloy

Magnesium (Mg) grains show anisotropic corrosion behavior, which implies that the single-phase, hot-rolled Mg alloy AZ31 sheet, if highly textured, will have different corrosion performance depending on its crystallographic orientation of the grains. Its rolling surface, dominated by (0001) basal crystallographic planes, is more corrosion resistant than its cross-section surface, which is mainly composed of $ \{ 10\overline{1} 0\} $ and $ \{ 11\overline{2} 0\} $ prismatic crystallographic planes. Furthermore, grain refinement by hot rolling is beneficial to the overall corrosion resistance of AZ31 because of the dissolution of AlMn(Fe) intermetallic precipitates in the alloy. Surface compressive deformation machining can lead to refined grains and an expected preferred grain orientation, thus improving the corrosion resistance of AZ31 alloy.     

Interpretation of hot rolling and cold rolling texture in high purity aluminium

In high purity aluminium two different types of hot band textures were produced by changing the final hot rolling temperatures. The texture of the hot bands was found to be inhnmogeneous through thickness. The strong preferred orientation of {001}<110> developed in the surface layer of the hot band which had been rolled at the higher finishing temperature. For the lower finishing temperature sample, the cold rolling type of texture was formed in the hot band. The cold rolling texture was dependent on the initial hot rolling texture. The hot band which had strong {001}<110> at the surface layer led to the maximum orientation density at {44 11}<11 11 8> after the subsequent cold rolling. Preferred orientations near {123}<634> in the hot band caused the maximum at {123}<634> in the cold rolling texture. The experimental results were discussed based on the simulation test of deformation texture in which the rotation of orientations was calculated from the Taylor model. In this calculation, the strain state of the deformation zone in the rolling gap is assumed to vary with shears induced from the geometry and the friction.