激光快速成形TA15钛合金热处理组织及其力学性能

Heat-Treated Microstructures and Mechanical Properties of TA15 Titanium Alloy Fabricated by Laser Rapid Forming

采用激光快速成形方法制备了TA15(Ti-6Al-2Zr-1Mo-1V)钛合金厚壁件,研究了不同退火温度对激光快速成形TA15钛合金组织和室温拉伸力学性能的影响。结果表明,随着退火温度的升高,粗大β晶内的初生α相板条体积分数减少,而β转变组织体积分数增加,且β转变组织形貌由板条状(β)→层片状(α+β)→细层片状(α+β)转变。力学测试结果表明,经940℃/1h,空冷热处理后,激光快速成形TA15钛合金室温拉伸力学性能达到最优;而当退火温度大于等于970℃时,其室温拉伸力学性能大幅度降低,拉伸断口扫描电镜(SEM)照片表明,室温拉伸断裂为脆性断裂。

A thick-wall part of TA15（Ti-6Al-2Zr-1Mo-1V） titanium alloy is prepared by laser rapid forming（LRF）.The influence of annealing temperature on the microstructures and the tensile properties at room temperature of laser rapid formed TA15 titanium alloy is also investigated.Results show that the volume fraction of primary α lath inside coarse β grain decreases and that of the transformed β increases,and the pattern of the transformed β changes from lath（β）→layered tablets（α＋β）→finer layered tablets（α＋β） with the annealing temperature increasing.Results also show that after the heat treatment of 940 ℃/1 h,air cooling,the tensile properties of the formed TA15 alloy are optimal;when the annealing temperature is no less than 970 ℃,the tensile properties of the formed TA15 alloy decrease greatly,and the fractographs show that the tensile failures are brittle fracture.