Discontinuous grain growth in an equal-channel angular pressing processed Fe-9Cr steel with a heterogeneous microstructure
Discontinuous grain growth in an equal-channel angular pressing processed Fe-9Cr steel with a heterogeneous microstructure
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DOI：
10.1016/j.matchar.2019.110004
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发表时间：
2020
影响因子：
4.7
通讯作者：
J. Duan;Haiming Wen;Caizhi Zhou;Xiaoqing He;R. Islamgaliev;R. Valiev
中科院分区：
文献类型：
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作者：
J. Duan;Haiming Wen;Caizhi Zhou;Xiaoqing He;R. Islamgaliev;R. Valiev
采用等通道转角挤压（ECAP）工艺对含颗粒Fe-9 Cr钢进行6道次Bc变形，获得了大角度晶界（HAB）和小角度晶界（LAB）不均匀分布的超细晶组织。在ECAP处理的Fe-9 Cr上从500 ° C至700 °C进行退火达48小时。发现UFG微观结构在高达550 °C下是稳定的。在600 °C退火的样品中首先观察到不连续的晶粒生长，伴随着LAB分数的增加。在高温退火（650-700 °C）期间，不连续的晶粒生长变得明显，导致LAB分数的减少和晶粒尺寸的显著增加。晶粒长大是硬度下降的主要原因。有人建议，在目前的异质微观结构，晶粒生长最初发生在占主导地位的HABs的区域，随后发生在主要由LAB的区域，从而形成双峰微观结构。退火结构的织构被示出为与ECAP处理结构的织构相似。在当前情况下，退火组织中的异常晶粒和基体之间的织构没有差异。
A particle-containing Fe-9Cr steel was processed by six passes of equal-channel angular pressing (ECAP) using route Bc to produce an ultrafine-grained (UFG) microstructure with a heterogeneous distribution of high-angle boundaries (HABs) and low-angle boundaries (LABs). Annealing was carried out on the ECAP-processed Fe-9Cr from 500 to 700 °C, for up to 48 h. It was found that the UFG microstructure was stable up to 550 °C. Discontinuous grain growth was first observed in the sample annealed at 600 °C, accompanied by an increase in LAB fraction. The discontinuous grain growth became evident during high temperature annealing (650–700 °C), leading to a reduction in LAB fraction and a significant increase in grain size. Grain growth was the main reason for the decline in hardness. It is proposed that in the current heterogeneous microstructure, grain growth initially occurs in regions of dominantly HABs, and subsequently takes place in regions that mainly consist of LABs, thereby forming a bimodal microstructure. Textures of the annealed structure were shown to be similar to those of the ECAP processed structure. No differences in textures were found between abnormal grains and the matrix in the annealed structure in current case.