固溶温度对SLM成形车用Ti基合金组织和力学性能的影响

Effect of solution temperature on microstructure and mechanical properties of Ti-base alloy for SLM forming vehicle

选择激光选区熔融(SLM)处理方法制得Ti-48Al-2Cr-2Nb高强度合金材料,设置了不同热处理工艺条件,并对比了各条件下的合金组织结构与力学特性差异。研究结果表明:成形态组织存在体心立方β相,形成了粗糙的表面形貌,可观察到许多明显凹坑与凸起结构。未经固溶处理的组织主要包含α相和β相;逐渐提高固溶温度后,形成了更大的晶粒,固溶温度950℃时获得了接近90μm的晶粒尺寸,得到α相与β基体组织,在晶界区域形成了更加破碎的γ相。成形态试样经力学性能形成明显韧性变形特点。热处理后形成了具有明显脆性变形特点,使材料达到更高力学强度。提高时效温度后,强度也随之上升。该研究为推广车轻量化用Ti-48Al-2Cr-2Nb材料提供了较大的理论支持。

Ti-48Al-2Cr-2Nb high strength alloy materials were prepared by selective laser melting(SLM)treatment method.Different heat treatment conditions were set and the differences in microstructure and mechanical properties of the alloys under different conditions were compared.The results show that there is a body-centered cubicβphase in the morphologic structure,and the rough surface morphology is formed.Many obvious pits and protrusions are observed.The tissue without solution treatment mainly containsαphase andβphase.When the solution temperature is increased gradually,l arger grains are formed,and the grain size is close to 90μm when solution temperature is 950℃.The needle-shapedαS phase andβmatrix structure are obtained,and more fracturedγphase is formed in the grain boundary region.The morphologic specimens have obvious ductile deformation characteristics through mechanical properties.After heat treatment,the material has obvious brittle deformation,which makes the material reach higher mechanical strength.When the aging temperature is increased,the strength also increases.This study provides great theoretical support for the extension of Ti-48Al-2Cr-2Nb materials for vehicle lightweight.