激光熔化沉积TC18钛合金组织及缺口高周疲劳性能  

Microstructure and notched high-cycle fatigue property of laser melting deposited TC18 titanium alloy

作　　者：王洋[1] 张述泉[1] 刘长猛[1] 汤海波[1] 

机构地区：[1]北京航空航天大学激光材料制备与成形实验室,北京100191

出　　处：《金属热处理》2013年第5期10-13,共4页Heat Treatment of Metals

基　　金：教育部长江学者和创新团队发展计划(IRT0805);国家重点基础研究发展计划(2011CB606305)

摘　　要：研究了激光熔化沉积TC18钛合金沉积态及热处理后的组织,以及室温缺口高周疲劳裂纹萌生和扩展特性。激光熔化沉积态组织由具有沿沉积方向定向生长特征的短柱晶及等轴晶组成,晶粒内部为超细的网篮组织;通过双重退火处理后,组织转变为较粗大的片层状网篮组织。研究表明,随着试样最大循环应力的升高,主裂纹长度降低,疲劳寿命也降低;激光熔化沉积TC18钛合金缺口疲劳裂纹源唯一,且起源于缺口根部表面处;疲劳裂纹扩展区发现两种类型的二次裂纹,二次裂纹有助于消耗裂纹扩展能,有助于提高疲劳极限。Microstructure and high-cycle fatigue property of notched specimens of laser melting deposited （LMD） TC18 titanium alloy were investigated. The results show that as-deposited microstructure consists of directional short column grains and equiaxial grains, with extremely fine basket-weave microstructure. After double-annealing treatment, coarse lamellar-like basket-weave microstructure was obtained. With the inc, reasing of maximum cyclic stress, the length of main crack and fatigue life decreased. The SEM micrographs indicate that the notched fatigue crack source of LMD TC18 titanium alloy was alone and initiated at the surface of the notch root. Two types of secondary cracks were detected at the fatigue crack propagation zone. The secondary cracks help consume energy and improve the fatigue strength.

关 键 词：钛合金 组织 疲劳 激光熔化沉积(LMD) 

分 类 号：V252[一般工业技术—材料科学与工程] TG146.23[航空宇航科学与技术—航空宇航制造工程]