摘要
通过控制热处理工艺条件,使钛合金的组织成为片层组织（lamellar microstructure,LM）和双态组织（bimodal microstructure,BM）两大类,研究了组织类型对其拉伸变形行为和低周疲劳（low cycle fatigue,LCF）行为的影响规律。研究结果表明,BM组织TC21合金的变形,以位错优先在αp相和条状次生α相中的增殖和运动为主导;粗大的LM组织中的退火孪晶改变了部分晶体的取向,增大了断裂前的塑性变形量,使TC21合金发生延性断裂。BM组织Ti600合金中的αp相阻碍LCF裂纹的扩展,消耗较多的LCF裂纹扩展能量,提高了Ti600合金的LCF寿命;热暴露（thermal exposure,TE）过程中,α2相由BM组织中的αp相析出,强化了αp相,导致BM＋TE试样的LCF裂纹主要以＂绕过＂αp相的方式扩展,而BM试样的LCF裂纹则以＂切过＂αp相的方式扩展,裂纹＂绕过＂αp相的扩展能量高于＂切过＂的能量,因此,α2相在αp相内部的析出提高了Ti600合金的LCF寿命。
Titanium alloy obtained lamellar microstructure（LM）and bimodal microstructure（BM）microstructures by the controlling of heat treatment parameters.Moreover,the tensile deformation behavior and effects of microstructure type on low cycle fatigue（LCF）behavior were investigated.The results indicate that TC21 alloy with coarse LM microstructure occur ductile rupture,since the annealing twins change the crystal orientation of part lamellar,and increase the plastic deformation degree before rupture.Dislocation multiplication and movement inαp phase and lathlike secondαphase is the dominant factor for the deformation behavior of TC21 alloy with BM microstructure.Theαpphase in BM microstructure can hinder the LCF crack propagation direction.Moreover,the absorbed energy of crack propagation can be increased by theαpphase.Therefore,the LCF lives were enhanced because ofαpphase.The resistance for LCF crack propagation ofαpphase in BM microstructure can be increased by the precipitation of α-2 phase,since the harder α-2 phase precipitated in theαpphase during thermal exposure（TE）.For the BM＋TE specimens,the crack mainly passes through theαpphase with＂bypass＂,while,for the BM specimens,the crack passes through theαpphase with＂cutting＂.Therefore,the LCF lives of Ti600 alloy after thermal exposure become longer because that the α-2 phase precipitated inαpphase.
作者
刘晓斌
翟羽佳
于腾
LIU Xiao-bin;ZHAI Yu-jia;YU Teng(Fushun Special Steel Co. Ltd., Fushun 113001, Liaoning, China)
出处
《金属功能材料》
CAS
2018年第3期25-30,共6页
Metallic Functional Materials
关键词
钛合金
显微组织
LCF行为
拉伸变形行为
titanium alloy
microstructure
LCF behavior
tensile deformation behavior
