激光熔化沉积法制备2A50铝合金热处理工艺研究

Research of Heat Treatment Process on Microstructure and Properties of 2A50 Aluminum Alloy Prepared by Laser Melting Deposition

摘要:

基于激光熔化沉积技术进行了高强度锻造型2A50铝合金增材制造实验,为了提高增材构件的综合力学性能,开展了增材制造高强度铝合金的热处理工艺研究。结合X射线衍射分析仪(XRD)、扫描电子显微镜(SEM)、显微硬度仪以及拉伸试验等检测手段,研究了不同热处理工艺参数对增材试样微观组织及力学性能的影响规律。结果表明：沉积态试样具有明显的柱状树枝晶结构,热处理后粗大柱状树枝晶发生断裂,晶粒开始球化并在晶界处形成均匀分布的块状第二相；在优化的热处理工艺条件下(540 ℃×1 h+150 ℃×16 h),结合溶质元素的固溶强化与第二相的析出强化作用,增材试样的屈服强度、抗拉强度、显微硬度的平均值分别由沉积态的90.7 HV、85 MPa、207 MPa提高至热处理后的137.2 HV、245 MPa、321 MPa。

Abstract:

In order to improve the comprehensive mechanical properties of additive components, the heat treatment process of high strength wrought 2A50 aluminum alloy was studied. The effects of different heat treatment parameters on the microstructure and mechanical properties of additive samples were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness tester and tensile test. The results show that the as deposited samples have obvious columnar dendrite structure. After heat treatment, the coarse columnar dendrites fracture, and the grains begin to spheroidize and form a uniformly distributed massive second phase at the grain boundary. Under the optimized heat treatment conditions (540 ℃ × 1 h+150 ℃ × 16 h), combined with the solid solution strengthening of solute elements and the precipitation strengthening of the second phase, the average values of yield strength, tensile strength and microhardness of the additive samples increased from 90.7 HV, 85 MPa and 207 MPa in the as deposited state to 137.2 HV, 245 MPa and 321 MPa after heat treatment, respectively.