Fabricating the steam turbine blade by direct laser forming

Direct Laser Forming (DLF) is a new layer additive manufacturing technique. It is difficult to control the forming process because many technological parameters interplay. Besides three kinds of laser scanning modes (namely, offset contour line mode, parallel line mode, and the offset contour line combined with parallel line fill mode), the effect of the defocusing amount of both laser beam and powder stream on the forming process is investigated in detail in the article. It is shown that the forming quality is better when the defocusing amount of both laser beam and powder stream are, respectively, between -0.5mm to 0.5mm and -3mm to -1mm, and at the same time, the self-healing phenomenon (namely, the plane quality of the top surface of part tends to decrease) is firstly found under the open loop condition. Based on the forming mechanisms under different defocusing amount, and the comparative study of three kinds of laser scanning modes, high definition steam turbine blade is fabricated by DLF using the hybrid scanning mode. Consequently, some complex metal parts in aerospace field can be near-net-shape formed by DLF.