激光选区熔化增材与机加工复合制造AISI 420不锈钢:表面粗糙度与残余应力演变规律研究

Selective Laser Melting and Subtractive Hybrid Manufacture AISI420 Stainless Steel: Evolution on Surface Roughness and Residual Stress

激光选区熔化(Selective laser melting,SLM)增材制造技术具备极端复杂构件制造能力,为高性能构件的材料结构一体化制造提供了技术支撑。然而,在激光与材料交互作用过程中,熔池稳定性,熔池间界面结合性,熔体与基体的润湿性等因素直接影响构件微观组织、表面精度与粗糙度。其中,SLM成形的金属表面粗糙度较高是制约其发展的重要因素,SLM技术与机加工复合是发展趋势之一。因此,采用机加工的方法对SLM样品进行表面处理,分别研究了机加工对不同致密度金属,不同铣削深度及不同铣削面对金属试样粗糙度及残余应力的影响规律。其中,试样粗糙度经过铣削后从约10μm降低到1μm以下,极大改善了制件的表面质量。同时,通过铣削使试样水平方向的残余应力由压应力变为拉应力并大幅降低。

Selective laser melting has the ability to produce extremely complex components, providing technical support for materials and structures integrated manufacturing of high performance components. Stability of molten pool, interfacial bonding property of molten pool and wettability of melt and substrate have an influence on microstructure, surface precision and roughness of components during the interaction of laser and material. Thus, high surface roughness of SLMed parts limits its development. Selective laser melting and subtractive hybrid manufacture is one of the development trends. Therefore, the milling method is taken to improvement surface quality of SLM-processed samples. Influence of surface roughness and residual stress by different porosity, different milling depth and different milling surface is studied. Surface roughness has been greatly improved and decreased from 10 μm to 1 μm after milling. The horizontal direction residual stress of the sample has changed from compressive stress to tensile stress and reduced a lot by milling.