通过多级热处理实现选区激光熔化Ti-6Al-4V合金强度与塑性平衡

Realizing strength and plasticity balance of selective laser melting fabricated Ti-6Al-4V alloy through multistage heat treatment

选区激光熔化制造Ti-6Al-4V合金通常表现出高强度与低延展性,需要通过热处理将针状α'马氏体分解为平衡的α+β相来获得优异的力学性能。在优化SLM成形工艺参数的基础上,系统研究了多级热处理对Ti-6Al-4V合金显微组织与拉伸性能的影响。试验结果表明:在最佳工艺参数下,SLM制备Ti-6Al-4V合金的相对密度为99.66%。经应力消除、固溶时效、热等静压处理后,Ti-6Al-4V合金获得了近等轴β晶粒内α集束组成的魏氏组织,相比SLM制造Ti-6Al-4V合金柱状β晶粒内的针状α'马氏体,屈服强度降低252MPa,抗拉强度降低312MPa,伸长率提高8%~9%,拉伸性能满足ASTM F2924-14:2014的指标要求,实现了强度与塑性的平衡。

Selective laser melting(SLM)manufacturing of Ti-6Al-4V alloy typically exhibits high strength and low ductility,requiring heat treatment to decompose acicularα'martensite into balancedα+βphases to achieve excellent mechanical properties.Based on optimizing SLM forming process parameters,this study systematically investigated the effect of multi-stage heat treatment on the microstructure and tensile properties of Ti-6Al-4V alloy.The experimental results demonstrated that the Ti-6Al-4V alloy fabricated through SLM exhibits a relative density of 99.66%under the optimal process parameters.After undergoing stress relieving,solution-aging,and hot isostatic pressing treatments,the Ti-6Al-4V alloy obtained a Widmanstädter structure consisting ofαcolony within nearly equiaxedβgrains.In comparison to the acicularα'martensite within the columnarβgrains of SLM-manufactured Ti-6Al-4V alloy,the yield strength and tensile strength decreased by 252MPa and 312MPa,respectively,while the elongation at break increased by 8%~9%.The tensile properties meet the requirements of ASTM F2924-14,achieving a balance between strength and plasticity.