Formation Mechanism of New Grains in Dynamic Recrystallizaion based on Local Orientation Analysis

基于局部取向分析的动态再结晶新晶粒形成机制

基本信息

批准号：
14550684
负责人：
FUKUTOMI Hiroshi
金额：
$ 2.05万
依托单位：
Yokohama National University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

In order to clarify the mechanism of new grain formation in dynamic recrystallization, the texture formation in γ-TiAl, nickel and copper during dynamic recrystallization (DRX) in compression was studied in relation to the microstructural evolution and grain boundary analysis. Compression tests were conducted at various temperatures and true strain rates ; the corresponding logarithmic value of Zener-Hollomon parameter lnZ ranged from 12.2 to 31.7. The behavior of texture formation was different, depending on the deformation conditions and the kind of materials.In low Z deformation conditions, DRX proceeded mainly through the process in which new grains are generated by strain induced migration of grain boundaries. In this case, the behavior of texture formation was different in γ-TiAl and in nickel and copper, texture developed sharply in γ-TiAl (the maximum pole density PMAX= 10) but it was not formed in nickel and copper (PMAX less than or equal 2). The difference in texture formati … More on was concluded to arise from the difference in the frequency of twin formation during grain boundary migration. That is, recrystallized grains change their orientation towards the stable orienctation for compression ({032) in γ-TiAl) and the texture, having this orientation as a main component develops, sharply when twinning scarcely occurs, while no texture develops when twinning occurs very frequently as in nickel and copper.In high Z deformation conditions, DRX proceeded through the nucleation and growth of new grains in the vicinity of grain boundaries where the deformation occurred severely and inhomogeneously. In this case, no notable difference in texture formation was found in each material ; the texture having a main component in or near the stable orientation for compression could certainly be observed though it was not sharp (PMAX=3-4).Both the value of PMAX and the frequency of twinning changed with the value of lnZ, but any discontinuous shift was not observed in their variation. This indicates that, with increasing lnZ, the behavior of texture formation changes gradually from that for low Z conditions to that for high Z conditions, depending on the proportion of the two processes of DRX, the bulging of grain boundaries and the nucleation and growth of new grains. Less

为了阐明动态再结晶中新晶粒形成的机制，结合微观结构演变和晶界分析，研究了压缩动态再结晶（DRX）过程中γ-TiAl、镍和铜的织构形成。在不同温度和真应变率下，相应的Zener-Hollomon参数lnZ的对数值范围为12.2至31.7，织构形成的行为不同。在低Z变形条件下，DRX主要通过应变诱导晶界迁移产生新晶粒的过程进行，在这种情况下，织构形成的行为与γ-不同。 TiAl以及镍和铜中，γ-TiAl(最大极密度PMAX=10)织构急剧发展，但镍和铜中织构不形成(PMAX小于或等于2)。 …更多结论是由于晶界迁移过程中孪晶形成频率的差异引起的，也就是说，再结晶晶粒将其方向改变为压缩方向（γ-TiAl 中的{032））和织构，从而具有这种特性。当孪晶很少发生时，作为主要成分的取向会急剧发展，而当孪晶频繁发生（如镍和铜）时，不会形成织构。在高 Z 变形条件下，DRX 通过成核进行在变形发生严重且不均匀的晶界附近，新晶粒的生长在这种情况下，在每种材料中未发现织构形成存在显着差异；具有处于或接近压缩稳定取向的织构可能存在。虽然不明显（PMAX=3-4），但肯定可以观察到。PMAX 的值和孪生频率都随 lnZ 的值而变化，但没有观察到它们的变化有任何不连续的变化。这表明，随着 lnZ 值的增加，它们的变化。 lnZ 中，织构形成行为逐渐从低 Z 条件向高 Z 条件变化，具体取决于 DRX 两个过程的比例、晶界的膨胀以及新晶粒的成核和生长。

项目成果

期刊论文数量（13）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

H.Okayasu, H.Fukutomi: "Deformation and Texture Behaviors of Al-3mass%Mg Alloy at High Temperatures"Proceedings of the International Body Engineering Conference (IBEC2003). 465-470

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