MICROSTRUCTURE EVOLUTION OF MARTENSITIC STAINLESS STEEL IN LASER HOT WIRE CLADDING WITH MULTIPLE HEATING PASSES

摘要

Laser cladding is one of attractive and cost effective means for repairing or remanufacturing high value engineering components. The microstructure and property in laser cladding process with multiple heating passes were investigated by using experimental method. Single-pass cladding experiments were conducted to investigate the wire transfer behavior and further optimize the laser hot wire cladding process. Multiple layers were cladded on the surface of martensite stainless steel by using fiber laser. The microstructure of clad layer and heat affected zone was characterized using an optical microscope, SEM and EDS. The orientation imaging microscopy of grain structure was obtained by the electron backscatter diffraction technique. The gradient microhardness from the clad layer to the substrate was tested. The uneven temperature distribution and high cooling rate led to the forming of gradient microstructure, and further affect the mechanical property of the remanufacturing parts.