高锰TRIP/TWIP钢压缩过程晶体学行为的EBSD分析 Ⅰ.相变特点、孪生及奥氏体取向的影响

来源期刊：金属学报2010年第6期

论文作者：杨平 鲁法云 孟利 崔凤娥

文章页码：657 - 665

关键词：高锰钢； EBSD； TRIP/TWIP； 马氏体相变； 取向

Key words：high manganese steel； EBSD； TRIP/TWIP； martensitic transformation； orientation

摘    要：本文利用EBSD技术研究了高锰钢压缩形变过程中γ→ε→α′马氏体相变的晶体学特点,分析了奥氏体孪生与奥氏体晶粒取向对相变的影响.结果表明,由于α′马氏体在2个ε变体的交叉处形成,而ε相变区域普遍存在奥氏体形变孪晶并且ε可在孪晶界上形成,因此孪生对相变起着重要的作用;而孪生的难易受奥氏体取向的影响.分析认为,低指数的{100},{111}和{110}奥氏体内因多变体同时孪生而比高指数取向容易促进ε变体间的交叉从而促进α′的形成;形变使ε变体数目或新取向增多,但小尺寸的ε难以促进α′的形成.

Abstract: The excellent combination of strength and elongation and the super work hardening behavior of high manganese TRIP/TWIP (transformation-induced plasticity/twinning-induced plasticity) steels are due to the presence of two kinds of martensitic transformations and their complicated interactions of three phases during deformation.This work investigated the crystallographic characteristics of γ→ε→α’ transformation,and in particular,the effects of deformation twins and austenitic grain orientations on martensitic transformation by means of EBSD technique.Results showed that α’-martensite was triggered at the intersection of two ε-martensite variants.Deformation twins were frequently detected near ε-martensite,thus twins promoted the formation of ε-martensite and played an important role during TRIP process.However,twinning was affected by austenite grain orientations.It is suggested that austenitic grain orientations with low indices,such as {100},{111} and {110},more easily promoted the intersection of ε-variants due to the multi-twinning and thus facilitated further α’-martensite formation than those with high indices.Deformation increased the number of ε variants but reduced their sizes and therefore it is difficult for the small strain-induced ε-martensites to transform into α’-martensites smoothly.