电子束直接金属成形技术的工艺研究

Technology Research of Direct Metal Forming Based on Electron Beam

基于电子束的直接金属成形技术利用电子束能量密度高、无反射以及真空加工环境无污染等优点，将电子束加工与快速原型制造技术相结合，可制造传统制造技术无法制造的复杂金属零件。本研究利用自行开发的电子束选区熔化成形设备进行了316L不锈钢粉末的试验研究，结果发现气雾化粉末具有较好的一维成形能力，但扫描速度不能太快；水雾化粉末聚球现象严重。通过工艺试验和数值模拟，得出气雾化粉末的比例在40％～60％之间的混合粉末具有较佳的成形性能，该粉末的成形过程分为粉末固定、粉末预热及粉末熔化3个阶段。采用电子束选区熔化成形的层片表面光滑平整，内部组织致密、细小，层间为冶金结合。

Direct metal forming technology based on electron beam is a new type of rapid manufacturing which combines electron beam machining and rapid prototyping and it makes use of the advantages of electron beam, such as high energy density, high absorption ratio and vacuum environment. In this study, different kinds of powder were researched on the electron beam selective melting （EB- SM-I） apparatus made by ourself. The one-dimension experiments showed that the gas atomized 316L stainless powder had well forming abilhy at low scanning speed and the water atomized powder had serious bailing phenomenon. The mixture powder which the weight proportion of the gas atomized powder was 40% -60% had the optimum forming ability and the forming process of this powder had divided into three steps： placing step, preheating step and melting step. The metal parts produced by EBSM have fine microstructure and good metallurgical bonding between layers, which indicates EBSM fits to direct metal forming and tooling.