低碳钢压缩变形时的形变不均匀性及其对铁素体转变的影响

宏观的形变不均匀性会导致相变和再结晶的差异 ,从而造成最终组织和性能的变化。本文观察并测量了单向压缩的低碳钢形变强化相变、铁素体热、冷形变时样品中心与边缘的铁素体形貌、珠光体或渗碳体分布和织构的差异。分析了不同区域相变及再结晶时的组织演变特点。讨论了形变储存能、渗碳体粒子及形变温度对铁素体相变及再结晶的影响。     

Influence of initial textures on dynamic recrystallization and textures in AZ31 magnesium alloys

1　INTRODUCTIONMagnesiumisthelightestmetallicstructurema terialwithhighspecificstrengthandthereforeiswidelyusedinautomotive ,electronicsandaerospaceindustries[1,2 ] .However ,magnesiumoftenshowsinsufficientplasticityatroomtemperatureduetoitsHCPstructurewithlessindependentsystemsofbasalslip .Toenhanceformabilityofmagnesium ,ahigherdeformingtemperatureisusuallyusedwithtwopur poses .Thefirstistoactivatenewslipsystemsbesidesbasalslip ,sothatmorethanfiveindependentslipsystemscanbeprovided ,be…     

微碳深冲钢板的再结晶与{111}织构的形成过程

采用试验和微观组织分析的方法,研究了冷轧微碳深冲钢板的再结晶组织和织构的特点以及AlN相析出对{111}织构形成过程的影响.研究结果表明,{111}织构从再结晶的形核阶段就已经开始形成,而且在其形成和初始长大过程中吞噬了非{111}织构组分.退火时采用慢速升温有利于AlN相充分析出和长大,促进了{111}织构的形成,从而抑制了非{111}织构组分,提高了微碳深冲钢板的成形性能.     

电场作用下AZ31镁合金的组织与织构的演变

利用X射线衍射技术（ODF分析）并结合透射电子显微镜观察（TEM）,研究了电场对A23l镁合金回复和再结晶的组织演变的影响,织构形成和发展的过程。结果表明：电场对镁合金回复和再结晶的作用不明显,使再结晶后的组织趋于均匀。再结晶织构的强度趋于一致。     

钽丝的拉拔及退火织构

对不同拉拔变形程度及不同温度退火后的钽丝织构, 借助极图与现代ＯＤＦ 分析术进行了研究。结果表明钽丝的拉拔织构主要聚集在α取向线上,形成〈１１０〉丝织构,织构组分主要有｛４４１｝〈１１０〉,｛３３２｝〈１１０〉,｛３３４｝〈１１０〉及｛１１５｝〈１１０〉。丝织构的形成与发展的主要特征可用｛１１０｝〈１１１〉位错滑移和轴对称变形的Ｔａｙｌｏｒ 完全限制模型进行解释。两种不同减面率的钽丝具有明显不同的退火织构组分。７７ ％ 冷拉减面率的钽丝退火后具有与拉拔丝基本相同的织构组分, 钽丝发生了原位再结晶。９０ ％ 冷拉减面率的钽丝低温退火后产生同样的效果, 然而经高温退火后出现新的织构组分｛１１１｝〈１１０〉和｛１１１｝〈１１２〉随退火温度的升高而增强, 其形成由定向长大机制控制。     

The deposition and recrystallization textures of copper electrodeposits obtained from a copper cyanide bath

The textures of copper electrodeposits obtained from an alkaline copper cyanide bath changed from <110> to <111> with increasing cathode current density and with decreasing bath temperature. The <111> and <110> textures of copper electrodeposits changed to the <100> and textures, respectively, when they were recrystallized. These results are similar to those in copper electrodeposits obtained from acid copper sulfate and acid copper fluoborate baths.     

电脉冲处理对低碳钢显微组织的影响

将15钢淬火-冷轧处理得到薄饼晶层状结构,在不同条件下对试样进行电脉冲处理,用TEM对组织结构进行对比观察,研究不同电脉冲处理条件对显微组织的影响.结果表明:电容量增加使温度升高达到再结晶温度是材料发生再结晶的主要因素,脉冲次数增加能促进材料再结晶;其它参数一定时,电容放电时间越短,组织细化效果越明显.     

Laser–ultrasonic absorption measurements in low carbon steels

We have refined the contactless laser–ultrasound reverberation technique to measure ultrasonic absorption on small metallic samples. In this technique, a sample is supported by a holder which is ultrasonically decoupled from the sample. A pulsed laser is used to generate an acoustic pulse. After the pulse has mode converted and scattered sufficiently to fully insonify the sample, the decrease in the noise-like ultrasonic signal is recorded as a function of time using a laser-interferometer. A joint time–frequency analysis technique is used to extract an absorption spectrum from the signal. In this paper, the technique is demonstrated in a frequency bandwidth ranging from 1 to 7 MHz, and in a dynamic range of 0.003 to 0.3 dB μs⁻¹. Measurements made on samples of three low-carbon steel grades, namely ultra low carbon (ULC), low carbon (LC), and high strength, low-alloy steels (HSLA), clearly show that ultrasonic absorption varies with steel grade. The technique was utilized to study the effect of a magnetic field on the ultrasonic absorption of an annealed ultra low carbon steel sample. It was found that magnetoelastic effects are responsible for a large fraction of the total absorption.     

The effect of precipitation on the evolution of recrystallization textures in an AA 8011 aluminum alloy sheet

The texture of an AA 8011 aluminum alloy sheet cold rolled by 95% showed a typical β-fiber, which runs from the copper orientation [C={112}〈111〉] over S [{123}〈634〉] to brass [B={011}〈112〉]. The development of annealing textures depended on annealing temperatures due to the interaction between precipitation and recrystallization. Upon annealing at a low temperature of 275°C, precipitation took place before recrystallization. This led to a weak recrystallization texture consisting of {011}〈122〉, {001∼〈100〉, and {hk0}〈001〉, among which the {011}〈122〉 orientation developed near large FeAl₃ particles as the main orientation and the cube [{001}〈100〉] orientation originating from the matrix was relatively weak. After annealing at 350 and 500°C, a strong cube texture developed along with a weak {011}〈122〉 orientation. When the cube orientation developed, the copper orientation disappeared most rapidly. These results were discussed based on the interaction between precipitation and recrystallization.     

低碳钢板冷轧退火组织和织构

分别采用基于薄板坯连铸连轧(CSP)工艺和传统热连轧工艺条件下的低碳钢板作为冷轧基料,在实验室模拟现场工艺进行了冷轧和退火。通过金相观察和X射线衍射织构分析,比较了两种工艺下低碳钢板的组织和织构演变的规律。结果表明:两种试样冷轧后α取向线上显著增加的织构有较大的区别,CSP工艺下是{001}〈110〉,而传统工艺下是{112}〈110〉;在同样的冷轧及退火工艺条件下,CSP条件下的钢板在退火过程中发生再结晶需要的温度更高,时间更长;对于CSP钢板,退火对γ取向线的影响要大于冷轧对其的影响,而对于传统热连轧钢板,冷轧和退火过程对γ取向线都有比较大的影响。     

预先热处理对6111铝合金冷轧及再结晶织构的影响

采用取向分布函数(ODF)法研究了预先热处理对6111铝合金的冷轧和再结晶织构组态的影响。结果表明:预先热处理因改变基体的成分和第二相的析出状态而显著影响6111铝合金的形变织构和再结晶织构;热轧板不经预处理而直接冷轧,其再结晶织构主要由绕法向旋转了15°的立方取向(Cube ND15)和{011}〈111〉取向构成;冷轧前进行过时效处理,其再结晶织构主要由绕法向旋转了20°的立方取向(Cube ND20)和{011}〈122〉取向构成;冷轧前进行固溶处理会显著提高冷轧织构中Brass和Goss组分的取向密度,再结晶织构明显弱化,而且Cube ND20组分绕法方向(ND)产生很大的漫散,接近于{001}〈UVW〉纤维织构。     

低碳Ti-Mo微合金马氏体钢的热变形行为

利用Gleeble-3800热模拟试验机对试验钢在950~1100 ℃,应变速率为0.1~5.0 s^-1,最大应变量为60%的条件下进行了热压缩模拟试验。结果表明：高变形温度、低应变速率和大变形量有利于动态再结晶,试验在1050 ℃、变形量60%、变形速率1 s^-1条件下得到圆整均匀再结晶晶粒,平均晶粒尺寸为14.84 μm;推演出低碳Ti-Mo微合金马氏体钢的形变激活能为462.8 kJ/mol及Z参数与动态再结晶变形条件的关系;建立起试验钢动态再结晶临界应变公式ε_c=0.3729Z^0.3496。     

7050铝合金板在固溶过程中微结构与织构的演变

采用光学金相(OM)、扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和织构材料(ODF)分析等研究7050铝合金热轧板在逐级升温固溶过程中微结构与织构的演变。结果表明:在固溶温度不超过490℃的条件下,板材中长条形再结晶晶粒平行于轧向分布,固溶板材与热轧板材的织构组态相似,均含有少量{001}100织构,晶粒取向主要聚集在β-取向线和α-取向线上;具有{124}211和{112}111取向的形变长条形组织由于回复和连续再结晶使其取向逐渐趋同,取向密度增强;最后经(475℃,12h)处理的样品中残留有Al2CuMg和Al7Cu2Fe相;而经(490℃,4h)处理的样品中,Al2CuMg相全部溶入基体,Al7Cu2Fe相仍然存在。     

钼对低碳微合金钢组织和性能的影响

研究了低碳微合金钢中Mo元素对形变奥氏体在连续冷却后组织和性能的影响。得出在此系列钢中，随Mo含量增加，针状铁素体量随之增加，同时钢中出现贝氏体束和M-A组织。屈服强度、抗拉强度随Mo含量的增加而提高，且抗拉强度的提高幅度高于屈服强度，屈强比随Mo的加入而降低，且随M～A组织增多，钢的冲击韧性损失加大。     

罩式退火对低碳钢冷轧板晶界特征分布及微区取向的影响

在实验室条件下模拟CSP(Compact Strip Production)热轧板为基板生产的低碳冷轧板罩式退火过程,研究再结晶阶段加热速度对冷轧板罩式退火过程晶界特征分布的影响。结果表明,在退火过程再结晶阶段加热速度为40℃/h的试样具有均匀的饼形晶粒组织,较高比例的{111}110和{111}112取向的晶粒。加热速度为40℃/h的试样含有的Σ3、Σ9、Σ13b晶界的比例高于加热速度为30℃/h的试样,Σ11晶界的比例则低于加热速度为30℃/h的试样。Σ3晶界随相邻同类型取向的增加而增多,Σ11晶界比例低时{001}110取向晶粒比例低、Σ13b晶界比例高时{111}取向晶粒比例高。     

电场退火对工业纯锌板再结晶织构的影响

利用X射线衍射的三维取向分布函数,研究工业纯锌板在160℃时电场与非电场退火保温不同时间条件下的再结晶织构的形成与演变,同时进行显微硬度测试。结果表明：电场退火推迟轧制工业纯锌板再结晶进程,从而导致电场退火样品的显微硬度值均高于非电场退火样品的显微硬度值。电场显著提高退火后样品的再结晶织构强度,即电场明显促进冷轧{101 8}面织构向再结晶{101 3}〈101 1〉板织构的演变,而且这种影响在再结晶晶粒的长大阶段表现得尤为突出。电场并没有改变工业纯锌板退火过程中再结晶织构的形成机制。     

Formation mechanisms of recrystallization textures in aluminum sheets based on theories of oriented nucleation and oriented growth

The recrystallization textures in 95% rolled aluminum sheets with different purities and initial textures were investigated. The effects of recovery levels and the dragging effects induced by impurities on the effective driving force and corresponding behaviors of oriented nucleation and oriented growth during annealing were analyzed. The oriented nucleation is a common behavior in the initial stage of primary recrystallization if the effective driving force in deformed matrix is not too high to reduce the necessity of nucleation period. Oriented growth might appear if the temperature is not too high and the grains, of which the misorientation to matrix is about 40°〈111〉, have enough time and space to expand growth advantages, while certain reduction of effective driving force is also necessary. The recrystallization textures could be changed by controlling initial textures and effective driving forces which can be regulated by recovery levels and dragging effects.     

Ti-6Al-4V钛合金搅拌摩擦焊缝的织构(英文)

采用W-Re合金搅拌头对α+β双相Ti-6Al-4V钛合金进行搅拌摩擦焊并在合适的工艺参数下获得无缺陷焊缝,利用取向成像显微镜对Ti-6Al-4V钛合金搅拌摩擦焊缝的织构进行研究。Ti-6Al-4V钛合金母材为轧制退火态,组织由变形的初生α相和转变β组织构成,具有典型的轧制织构。焊核区组织与母材明显不同,由大量的等轴动态再结晶晶粒组成,并在搅拌摩擦焊过程中形成{φ1=30°,φ=62°,φ2=30°}取向的织构。     

Effect of initial textures on texture formation in AA 3004 sheets during continuous confined strip shearing and subsequent annealing

The effect of initial textures on the texture formation during continuous confined strip shearing (CCSS) and subsequent annealing was investigated in AA 3004 sheets. The CCSS tools were designed to provide a constant shear strain of the order of 0.5 per pass while preserving the original sheet shape. During the CCSS deformation, the initial texture disappeared, and shear texture components developed. However, the intensity of the shear texture components did not further develop with an increasing number of CCSS passes. The softer initial sample depicting the cube texture displayed the evolution of {111}//ND fiber orientations. Upon recrystallization annealing, the textures developed during CCSS were randomized through the suppression of oriented nucleation and selected growth which generally dominate the evolution of recrystallization texture in cold rolled aluminum alloy sheets.     

Nb微合金化低碳贝氏体圆钢的组织细化

通过热模拟试验研究了Nb微合金化在长材低碳贝氏体钢中的作用机理。研究表明对该成分的低碳贝氏体钢采用线棒材轧制时,形变诱导析出Nb(CN)抑制再结晶主要发生在轧后过程中,抑制了轧后相变前的奥氏体晶粒长大,同时抑制了贝氏体板条束的长大。变形后在空冷条件下,3 s后开始发生明显的析出,在900℃以下变形,在贝氏体相变前,可获得约10μm的均匀细小的奥氏体晶粒。