Effect of composite adding Ta and Mo on microstructure and properties of W-Mo-Cr high-speed steel prepared by laser metal deposition

Abstract

W-Mo-Cr (M2) high-speed steel consisting of Tantalum or Molybdenum on #45 steel was prepared by a laser metal direct forming process. After the appropriate proportion of Ta or Mo powder is added, obvious grain refinement occurs, strengthening or toughening increase. On the basis of these work, the present study aims to harness the combined benefits of Ta and Mo by incorporating them into M2 HSS through laser metal deposition (LMD) technology, with the objective of achieving both high toughness and high hardness. The phase, microstructure, hardness, and wear resistance of the two kinds of steels are characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, hardness and wear tests. The results show that compared with the deposition state, the microstructure of the samples after adding Ta and Mo shows grain refinement and carbide aggregation. In addition, the hardness and impact toughness of the samples increase to different degrees. However, after combined adding Ta and Mo, the composite addition of Mo can continue to improve the performance on the basis of 1% Ta alloying alone. The hardness continues to increase by 3.6%, the wear loss decreases by 19.4%, and the impact toughness value increases by 22.7%. Mo shows good strengthening and toughening and nucleating agent effects.