摘要
选区激光熔化成形过程中金属粉末的快速熔化凝固会产生较大的热梯度,温度的动态变化对不同粉末成形零件的微观组织和力学性能产生影响。基于有限元分析软件,采用移动高斯热源(Gauss)加载对选区激光熔化成形过程进行三维瞬态温度场模拟,研究Hastelloy X和Ti6Al4V合金的不同属性与温度变化及凝固冷却规律。同时基于选区激光熔化工艺制备Hastelloy X和Ti6Al4V合金试样,对其微观组织和力学性能进行表征。结果表明:Hastelloy X和Ti6Al4V合金瞬态峰值温度分别达到2777.37℃、3340.88℃,平均冷却速率分别为3.93×106 K/s、5.11×106 K/s。在微观状态下,Hastelloy X合金晶粒呈现羽毛状层叠交叉排列,而Ti6Al4V合金内部分布着针状马氏体α′相交错形成网篮组织。相比Hastelloy X合金抗拉强度和屈服强度的728.08 MPa、338.91 MPa,在更高冷速下产生"细晶强化"作用的Ti6Al4V合金的抗拉强度和屈服强度达到了1134.05 MPa、1055.83 MPa,远高于Hastelloy X合金,但其伸长率却低于Hastelloy X合金,总体呈现高强度、低塑性的特点。
The rapid melting and solidification of metal powder in selective laser melting process will produce a large thermal gradient, and the dynamic change of temperature gradient will affect the microstructure and mechanical properties of different powder forming parts. Based on finite element analysis software, three-dimensional transient temperature field of selective laser melting forming process was simulated by using moving Gaussian heat source(Gauss) loading. The different properties, temperature changes and solidification cooling laws of Hastelloy X and Ti6 Al4 V alloys were studied. At the same time, Hastelloy X and Ti6 Al4 V alloy samples were prepared by selective laser melting process, and their microstructure and mechanical properties were characterized. The results show that the transient peak temperatures of Hastelloy X and Ti6 Al4 V alloys reach 2 777.37 ℃ and 3 340.88 ℃, and the average cooling rates are 3.93×106 K/s and 5.11×106 K/s, respectively. In the micro-state, grains of Hastelloy X alloy are arranged in feather-like lamination and cross-arrangement, while needle martensite α′ phases are distributed in Ti6 Al4 V alloy to form a net basket structure. Compared with 728.08 MPa and 338.91 MPa of tensile strength and yield strength of Hastelloy X alloy, the tensile strength and yield strength of Ti6 Al4 V alloy with "fine grain strengthening" effect at high cooling rate reach 1 134.05 MPa and 1 055.83 MPa, which are much higher than that of Hastelloy X alloy, but its elongation is lower than that of Hastelloy X alloy, which is generally characterized by high strength and low plasticity.
作者
宗学文
张健
卢秉恒
李伟东
Zong Xuewen;Zhang Jian;Lu Bingheng;Li Weidong(Cillege of Mechanical Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China;Institute of Additive Manu facturing Technology,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China;National Institute Cor poration of Additive Manufacturing,Xi'an,Shaanai 710300,China;College of Mechanical Engineering,Xi'an Jiaotong University,Xi'an,Shaanri710049,China;Luoyang Ship Material Research Institute,Luoyang,Henan 471023,China)
出处
《应用激光》
CSCD
北大核心
2021年第4期745-751,共7页
Applied Laser
基金
国家自然科学基金(51875452)
国家863计划项目(2015AA042503)。
