Direct metal part forming of 316L stainless steel powder by electron beam selective melting

Electron beam selective melting (EBSM) is a new type of rapid manufacturing of direct metal fabrication technology, which combines electron beam machining with rapid prototyping. It makes use of some advantages of an electron beam, such as high energy density, high absorption rate, and vacuum environment. In this study, direct metal part forming of gas and water-atomized 316L stainless steel powder were researched in detail. The one-dimensional experiments showed that the gas-atomized 316L stainless steel powder could be formed in a solid line at slow scanning velocity and low beam current while the water-atomized powder had serious balling and break-up phenomena at most conditions. The powder mixture containing 40-60 wt % of the gas-atomized powder has the optimum forming ability. The forming technology of the mixture powder must be divided into three steps: placing step, heating step, and melting step. After research on the technology parameters, some two-dimensional facets and three-dimensional parts were produced by EBSM. The microstructure of the three-dimensional forming parts was fine; the interfaces between the layers were metallurgically bonded.