针对送粉式激光沉积成形技术,选取不同的Z轴提升量成形316L不锈钢薄壁件,分别检测薄壁件不同区域的微观组织和力学性能,包括晶粒尺寸、重熔深度以及拉伸性能各向异性,并探究了单道熔覆层和薄壁件整体的晶粒形态以及生长方向。根据不同Z轴提升量下的微观组织,分析了薄壁件不同方向上抗拉强度和伸长率的变化规律。结果表明:不同于单道熔覆层,在不同的Z轴提升量下,薄壁件主要以柱状晶为主,并且不同区域的柱状晶的生长方向发生了变化;Z轴提升量与晶粒尺寸之间呈非线性关系;不同Z轴提升量下柱状晶的生长方向和尺寸会影响成形件拉伸性能的各向异性。

Thin-wall parts of 316L alloy are fabricated with different Z-increments using the powder-feeding laser metal deposition technology. The microstructure and mechanical properties such as the grain size, re-melting depth, and anisotropy of the tensile property of the thin-wall parts are explored at different positions. Moreover, the grain morphologies and growth directions of a single-pass cladding layer and the thin-wall parts are investigated. Based on the microstructure with different Z-increments, the tensile strength and elongation in different directions of the thin-wall parts are analyzed. The results demonstrate that for different Z-increments, the grain morphology of the thin-wall part is mainly columnar, which differs from that of the single-pass cladding layer. In addition, the growth direction of the columnar grain is different in different regions. There is a nonlinear relationship between the Z-increment and the grain size. The growth direction and size of the columnar grain of different Z-increments affect the anisotropy of the tensile property of the thin-wall parts.