LY12工业铝合金的超塑性预处理及超塑性拉伸变形研究

本文对工业铝合金LY12的超塑性预处理工艺及超塑性拉伸变形进行了试验与研究分析。结果表明:经过一定的锻造热变形与稳定化处理后,可以得到较细小均匀稳定的晶粒组织,具有超塑性性能,在430℃,ε=1.67×10~(-3)S~(-1)时,延伸率δ为255％,m值为0.3～0.36,它提供了利用超塑性成形的可能性。     

用喷射成形工艺生产的超高碳钢

成功地将喷射成形工艺应用于生产超高碳钢.利用喷射成形的快速凝固的特点,有效地避免了超高碳钢中碳的偏析问题.首次发现喷射成形的超高碳钢无须任何处理,即可具有超塑性,由此首次提出"自超塑化"的概念.利用这一特点,对喷射成形的超高碳钢施行大变形量的热加工,不仅进一步细化了组织,而且使材料致密化,从而达到强度约1 300 MPa、伸长率约10%的优良的综合力学性能.     

钢材超塑性扩散连接接头的质量分析

通过对４５／４５、Ｗ６Ｍｏ５ＣｒＶ２／４５钢的超塑性扩散连的室温力学性能、接头界面组织以及界面碳扩散等进行测试分析发现,在足够的预压力和良好的连接表面状态下,同种钢材的超塑性扩散连接接头形成了牢固冶金结合,接头界面层可以完全消失;异种钢材的超塑性扩散连接接头界面仍清晰可见,界面是由冶金结合区,机械结合区及显微空隙等组成     

喷射成形超高碳钢的自超塑化现象

用喷射成形工艺制备的无宏观偏析、组织为均匀细密珠光体的超高碳钢,无需任何热的或机械的预处理,即可具有伸长率达380%的超塑性,并且在2×10-1s-1的应变速率下仍有122%的伸长率.这是由于在此变形过程中发生了碳化物由片层状向颗粒状的转变并形成细小等轴晶粒的组织超塑化;而且高应变速率可促成高度细化的球化组织.由此开发的喷射成形结合大压下量热轧的方法可以简捷有效地使超高碳钢获得很好的超塑性,并且可以应用于高速钢等其它高碳钢铁材料.     

铝黄铜（HAl66—6—3—2）超塑性研究

本文研究了锻造性能差的工业常规材料HA166-6-3-2铝黄铜在供应状态下的超塑性,进行了超塑拉伸后显微组织分析和刻痕表观形貌观察,探讨了其大晶粒组织超塑性的变形机理。     

冷轧中锰钢的超塑性与组织结构演化行为

 为了研究含铝冷轧中锰钢的超塑性能和在超塑性变形下的组织结构演化过程,对冷轧含铝中锰钢在800 ℃进行了高温拉伸试验和不同变形量下的微观组织结构表征。研究结果表明,0.05C5Mn2Al、0.10C5Mn2Al和0.15C5Mn3Al钢伸长率分别达到了740%、850%和350%,都获得了超塑性现象,EBSD表征结果表明0.05C5Mn2Al、0.10C5Mn2Al两种冷轧组织均匀细小,在高温拉伸过程中具有较高的稳定性,拉伸过程中铁素体与原奥氏体均匀长大,且最大晶粒尺寸小于10 μm;但0.15C5Mn3Al冷轧组织存在条带状的铁素体,该组织易于通过吞并细小的铁素体和原奥氏体晶粒而异常长大,高温拉伸后的尺寸达到了20 μm。通过对3种含铝冷轧中锰钢的超塑性行为与微观组织结构演化关系分析,认为初始均匀一致的冷轧组织具有高的组织稳定性而有利于超塑性,而具有粗大条带状的铁素体组织易于发生异常长大而不利于超塑性。     

日本开发成功低成本的超硬铝新合金

日本开发成功低成本的超硬铝新合金Ａｌ－Ｚｎ系７０００系列超硬铝具有强度高、塑性好、耐腐蚀的特点，采用挤压加工即可制得复杂断面铝合金型材，因此被广泛应用于航空航天工业，如飞机的大梁、桁条、隔框、蒙皮、起落架等部件，但是由于这种合金生产成本高、价格昂贵、...     

一种Al-Mg合金薄板超塑性工艺研究

采用光学显微镜、透射电镜、X射线衍射和超塑性拉伸等试验对三种不同成分的Al-Mg合金薄板进行研究和对比,确定了具有优良超塑性能Al-Mg合金薄板的成分和制备工艺。     

超高强度热成形钢研究进展及展望

在“双碳”战略的大背景下，环保、节能等问题越来越受到重视，由此对汽车用钢轻量化提出了更高的要求，超高强热成形钢作为汽车用钢的重要组成部分，有着广阔的研究前景。概述了国内外热成形钢研究现状，从成分设计、组织特征、工艺调控等多个角度出发，总结出了微合金化和残余奥氏体组织调控对超高强热成形钢强塑化机制的影响规律；阐述了铝硅镀层、锌基镀层热成形钢及新型无镀层高抗氧化性热成形钢的研究进展；论述了超高强热成形钢微观组织与氢致延迟开裂行为之间的相互作用。对超高强热成形钢的进一步优化控制提出了建议，为实现高强塑性及优异服役性能的超高强热成形钢的研发与产业化应用提供了参考。     

大晶粒超塑性变形机理的研究

本文通过对供应状态铝锰β-黄铜超塑性的系统研究,探讨了其在大晶粒组织条件下的超塑性变形机理;应用刻痕实验和金相组织观察方法,发现了大量亚晶界和亚晶界的运动。根据实验结果分析和理论计算提出了亚晶界的移动和滑动是大晶粒超塑性变形的主导机制,由测量得知晶界滑动变形对总变形的贡献仅为～10％,这说明晶界滑动是调节机制。     

Effects of microstructural evolution on superplastic deformation characteristics of a rapidly solidified Al-Li alloy

This study is concerned with the effects of microstructural modification on superplastic deformation characteristics of a rapidly solidified (RS) Al-3Li-1Cu-0.5Mg-0.5Zr (wt pct) alloy. This Al-Li alloy has a very fine grain structure desirable for improved superplasticity. The results of superplastic deformation indicated that the alloy exhibited a high superplastic ductility, e.g., elongation of approximately 800 pct, when deformed at temperatures above 500 °C and at the strain rates of 10⁻²/s to 10⁻¹/s. Such a high strain rate is quite advantageous for the practical superplastic forming application of the alloy. Stress-strain rate curves were obtained by performing a series of load relaxation tests in the temperature range from 460 °C to 520 °C in order to examine the superplastic deformation behavior and to establish its mechanisms. The stress-strain rate curves could be separated into two parts according to their respective physical mechanisms, i.e., grain matrix deformation and grain boundary sliding, as was proposed in a new superplasticity theory based on internal deformation variables. The microstructural evolution during superplastic deformation was also analyzed by using transmission electron microscopy. During superplastic deformation, grains were kept fine and changed into equiaxed ones due to the presence of fine secondary phase particles and the continuous recrystallization due to the development of subgrains. Consequently, the rapidly solidified (RS) alloy showed much improved superplasticity compared to the conventional ingot cast 8090 alloy.     

The kinetics of transformation in Zn-Ai superplastic alloys

We report herein on the kinetics of transformation of a eutectoid Zn-AI alloy containing additions of Cu, Mg and Ca. The alloy possesses excellent superplasticity at elevated temperatures, and it has a relatively high strength at ambient temperature (∼345 MPa). TTT curves for the alloy are presented, and the corresponding microstructures obtained at the various transformation temperatures are reported. Also, the results of Jominy endquenched tests are reported and the corresponding continuous cooling kinetics are compared to the isothermal kinetics. The alloy was observed to decompose by two distinct mechanisms, depending upon the degree of supercooling. At temperatures just below the eutectoid, it decomposes into a lamellar microstructure, whereas at larger undercooling it decomposes into a coherent two-phase mixture. The interlamellar spacing and colony size are reported as a function of transformation temperature, and shown to follow expected trends. Since neither the lamellar nor coherent microstructure is superplastic, thermomechanical methods of producing a superplastic structure are discussed.     

单相组织金属间化合物的超塑性行为

在一定条件下具有单相微观组织的L12型[Ni3Al,Ni3(Si,Ti),Co3Ti],L10型（TiAl)和B2型（FeAl,Fe3Al,NiAl)金属间化合物均表现出超塑性行为。其中,L12型和L10型金属间化合物的超塑性变形机制为晶界的滑移,而B2型金属间化合物的超塑性变形则来自于变形过程中发生的动态回复及再结晶,超塑性变形机制的多样性是由于金属间化合物在微观组织及位错结构上（如反向畴界能,层错能和化学成分差异,超位错及界面位错等）比普通金属合金要复杂得多。     

The mechanical properties of superplastic materials

The relationship between stress and strain rate is often sigmoidal in superplastic materials, with a low strain rate sensitivity at low and high strain rates (regions I and III, respectively) and a high strain rate sensitivity at intermediate strain rates (region II) where the material exhibits optimal superplasticity. This relationship is examined in detail, with reference both to the conflicting results reported for the Zn-22 pct Al eutectoid alloy and to the significance of the three regions of flow. This paper is based on a presentation made at the symposium “On the Mechanical, Microstructural and Fracture Processes in Superplasticity” held at the annual meeting of the AIME in Pittsburgh, PA on October 7, 1980 under the sponsorship of the Flow and Fracture Activity of the Materials Science Division of ASM.     

Effect of Rare Earth on Superplasticity of Zn—5Al Eutectic Alloy

Zｎ Ａｌａｌｌｏｙｉｓｏｎｅｏｆａｌｌｏｙｍａｔｅｒｉａｌｓｗｉｄｅ ｌｙｕｓｅｄｉｎｉｎｄｕｓｔｒｙ .Ｚｎ 5Ａｌｅｕｔｅｃｔｉｃａｌｌｏｙｉｓｎｏｔｏｎｌｙｅｘｔｅｎｓｉｖｅｌｙｕｓｅｄａｓｄｉｅ ｃａｓｔｉｎｇａｌｌｏｙ ,ｈｏｔｐｌａｔｉｎｇａｎｄｓｐｒａｙｉｎｇａｌｌｏｙ ,ｂｕｔｏｂｔａｉｎｓｒｅｃｏｇｎｉｔｉｏｎｉｎｓｕｐｅｒｐｌａｓｔｉｃｓｈａｐｉｎｇａｎｄｓｕｐｅｒ ｐｌａｓｔｉｃｔｈｅｏｒｅｔｉｃａｌｒｅｓｅａｒｃｈｅｓｏｗｉｎｇｔｏｉｔｓｅｘ ｔｒａｏｒｄｉｎａｒｙｓｕｐｅｒｐｌａ…     

高强度锌铝合金研究

研究了高强度锌铝合金的熔炼工艺、机械性能和金相组织,并探讨了合金超塑性预处理工艺,进行了超塑性拉伸试验,获得最大延伸率可达900％,合金具有良好超塑性。     

镁合金的超塑性与损伤定量分析

研究了轧制AZ31B镁合金板材的超塑性与空洞损伤，对拉伸试样在超塑性变形各阶段轴剖面的空洞进行了观察，通过对空洞演化的分析建立了空洞体积分数与变形程度的定量关系。研究结果表明：AZ31B镁合金板材在一定的变形条件下具有良好的超塑性；变形伴随着空洞的形核、长大，继而发生空洞的连接，导致材料断裂；空洞体积分数随着变形程度的增加呈指数规律变化。     

挤压态AZ31B镁合金在超塑变形过程中的微观组织及力学性能研究

通过正向温挤压获得了细晶微观组织的AZ31B镁合金。研究了在310～460℃范围内,应变速率1×10-3～1×100/s下的超塑性流变行为。结果表明,在415℃、1×10-3/s的条件下AZ31B镁合金具有良好的超塑性,最大延伸率可达380%。应变速率敏感指数达到0.47。通过光学显微镜和扫描电镜（SEM）分别观察了AZ31B镁合金在超塑变形过程中的微观组织演变和断口形貌。晶界滑移机制为AZ31B超塑变形的主要机制。     

Correlation between former alpha boundary growth kinetics and superplastic flow in Zn-22 pct Al

Former α boundaries (FαBs) are residual grain boundaries that develop in Zn-22 pct Al during a heat treatment, which is normally applied to produce the fine structure necessary for micrograin superplasticity. They represent domains consisting of fine elongated α grains, which encompass groups of fine α (Al-rich) and β (Zn-rich) phases (the superplastic microstructure). The results of a detailed investigation conducted on FαB growth kinetics in five grades of Zn-22 pct Al with various impurity contents reveal a direct correspondence between the level of impurities in the alloy and the characteristics associated with FαBs (average size of FαBs and the value of the FαB growth exponent). This correspondence, which, according to available evidence, is the result of impurity segregation at FαBs, lends strong support to the interpretation of superplastic behavior at low stresses in terms of phenomena arising from boundary segregation. It is suggested that information on FαB growth kinetics in Zn-22 pct Al can be utilized to predict the low-stress superplastic characteristics of the alloy, such as the existence of region I or the occurrence of extensive cavitation.