热处理对选区激光熔化Ti-6Al-4V合金低周疲劳性能的影响

Effect of Heat Treatment on Low Cycle Fatigue Properties ofSelective Laser Melting Ti-6Al-4V Alloy

摘要:

为提高选区激光熔化Ti-6Al-4V合金的低周疲劳性能,利用OM、SEM、TEM、室温拉伸及低周疲劳试验研究了热处理对选区激光熔化Ti-6Al-4V合金组织及性能的影响。结果表明,沉积态组织表现为外延生长的β柱状晶及晶内呈一定取向关系的针状马氏体α",经退火后α"发生分解转变为网篮编织状的α+β,经循环热处理后板条α发生球化,组织由等轴α、板条α和残余β构成。经热处理后,退火态低周疲劳性能达到锻件的87%以上,循环热处理态达到锻件的90%以上。

Abstract:

In order to improve the low cycle fatigue property of selective laser melting Ti-6Al-4V alloy,the effects of heat treatment on the microstructure and properties of selective laser melting Ti-6Al-4V alloy were studied by using OM,SEM,TEM,room temperature tensile and low cycle fatigue tests.The results show that the as-built microstructure is characterized by epitaxially grown β columnar grains and acicular martensite α" with a certain orientation in the grains.After annealing,α" decomposes and transforms into basket-weave α+β.After cyclic heat treatment,lath α becomes globularized,and the microstructure is composed of equiaxed α, lath α and residual β.After heat treatment,the low cycle fatigue property of the annealed state reaches more than 87% of the forgings,which reaches more than 90% of the forgings for the cylic heat treated state.