激光功率与曝光时间对选区激光熔化TC11钛合金组织与力学性能的影响

Effects of laser power and exposure time on microstructure and mechanical properties of selective laser melting of TC11 titanium alloy

采用选区激光熔化技术成形TC11钛合金试样,研究了激光功率(220~260 W)和曝光时间(45~55μs)对试样组织和力学性能的影响。结果表明,激光功率与曝光时间主要影响成形过程中的激光功率密度,从而造成组织、力学性能差异:当激光功率密度增加时,液态停留时间相对较长和冷却速率相对较低,柱状晶尺寸相对粗大,马氏体板条尺寸增加;当曝光时间为50μs、激光功率增加到260 W时,SLM成形试样的显微硬度增加至437 HV0.3,抗拉强度增加至1 463 MPa,而断后伸长率降至6.0%;当激光功率为200 W、曝光时间增加到55μs时,SLM成形试样的显微硬度增加至404.2 HV0.3,抗拉强度增加至1 446 MPa,而断后伸长率降至4.8%。当激光功率为220 W、曝光时间为50μs时,可获得强度和塑性匹配较佳的TC11钛合金,其抗拉强度和断后伸长率分别为1 345 MPa和10.6%。

TC11 titanium alloy samples were formed by selective laser melting technology,the effects of laser power(220-260 W)and exposure time(45-55μs)on the microstructure and mechanical properties of the samples were studied.The results show that the laser power and exposure time mainly affect the laser power density during the forming process,resulting in differences in microstructure and mechanical properties:when the laser power density increases,the liquid retention time is relatively long,the cooling rate is relatively low,the columnar crystal size is relatively large,and the martensite lath size increases;When the exposure time is 50μs and the laser power is increased to 260 W,the microhardness of SLM forming specimen increases to 437 HV_(0.3),the tensile strength increases to 1463 MPa,and the elongation after fracture decreases to 6.0%;When the laser power is 200W and the exposure time is increased to 55μs,the microhardness of SLM formed specimen increases to 404.2 HV_(0.3),the tensile strength increases to 1446 MPa,and the elongation after fracture decreases to 4.8%.When the laser power is 220W and the exposure time is 50μs,TC11 titanium alloy with better matching strength and plasticity can be obtained,and its tensile strength and elongation after fracture are 1345 MPa and 10.6%respectively.