激光熔化沉积TC11钛合金的疲劳裂纹扩展行为  

Fatigue Crack Growth Behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy Prepared by Laser Melting Deposition

作　　者：刘鹏飞 陆兴[1] 覃作祥[1] 吕云卓 罗剑 LIU Pengfei;LU Xing;QIN Zuoxiang;LV Yunzhuo;LUO Jian(School of Materials Science and Engineering,Dalian Jiaotong University,Dalian 116028,China)

机构地区：[1]大连交通大学材料科学与工程学院,辽宁大连116028

出　　处：《大连交通大学学报》2019年第1期67-71,共5页Journal of Dalian Jiaotong University

摘　　要：研究了激光熔化沉积Ti-6.5Al-3.5Mo-l.5Zr-0.3Si(TC11)合金疲劳裂纹扩展行为.研究结果表明:TC11合金裂纹扩展遵循Paris关系,沉积的各向异性导致了平行沉积方向与垂直沉积方向的疲劳裂纹扩展性能参数即疲劳门槛值"Kth、C和m有较大差异,其分别为5.05 MPa·m1/2,1.73×10-10和4.38与7.04 MPa·m1/2,4.51×10-10和4.04.初生β相柱状晶是导致产生这一差异的主要原因.应力水平影响低"K下的疲劳裂纹扩展行为,高应力水平下的疲劳裂纹扩展行为敏感尺寸达到片层集束尺寸单元,低应力水平下的疲劳裂纹扩展行为敏感尺寸则与单个α、β片层的细小组织单元相当.The fatigue crack growth behavior of the Ti-6.5Al-3.5Mo-l5Zr-0.3Si alloy prepared by laser melting deposition is investigated.The results show that the fatigue crack growth follows the Paris relation,and the deposition anisotropy leads to the great difference of the fatigue crack growth performance parameters(ΔK th,C and m)between the parallel and the vertical deposition directions,which are 5.05 MPa·m 1/2,1.73×10-10,4.38 and 7.04 MPa·m 1/2,4.51×10-10,4.04,respectively.The priorβphase columnar grains generated by laser melting deposition are the main reason leading to this difference.Low K stress level produces an effect on the fatigue crack growth behavior,and the fatigue crack growth behavior sensitive size under high stress level reaches lamellar column size unit.However,the sensitive size under low stress level corresponds to singleα、βlamellar small microstructure unit.Basal slip system is the most favorable slip mode for the fatigue crack growth of the TC11 alloy prepared by laser melting deposition.

关 键 词：激光熔化沉积 钛合金 显微组织 疲劳门槛值 疲劳裂纹扩展行为 

分 类 号：TG665[金属学及工艺—金属切削加工及机床] TG146.23[一般工业技术—材料科学与工程]