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一、引言钛合金铸态组织由魏氏α与粗大的晶界α所组成,室温塑性低,疲劳强度差。使铸造钛合金获得细小等轴晶粒的传统方法是进行大变形量加工以及相应的热处理。近年来,出现一种用单纯的热处理细化粗大魏氏组织的方法,即循环热处理;并对其实用性进行探索,取得了一定的进展。本文主要研究BT9合金的原始铸态组织及其相成分在循环热处理过程中的变化情况,探讨用热处理方法细化粗大魏氏组织的机理。
I. INTRODUCTION The as-cast microstructure of titanium alloy is composed of Wei’s α and coarse grain boundary α, with low plasticity at room temperature and poor fatigue strength. The traditional method of obtaining fine equiaxed grains of a cast titanium alloy is to carry out a large amount of deformation processing and a corresponding heat treatment. In recent years, a method of refining the coarse Widman’s tissue by a simple heat treatment has emerged, that is, a cyclic heat treatment; and its practicality has been explored and some progress has been made. In this paper, we mainly study the changes of the original as-cast microstructure and phase composition of BT9 alloy during cyclic heat treatment and discuss the mechanism of refining the coarse Widman’s tissue by heat treatment.