In-situ observation of CO gas bubble behavior in molten pool during direct laser deposition of WC-Co cermet material

Abstract

Laser cladding of WC-Co cermet material is a promising means of improving the wear resistance of metal products. Layer-by-layer processing of laser cladding, also designated as laser directed energy deposition and laser metal deposition, is attracting attention as an alternative manufacturing process of cermet materials for conventional powder metallurgy processing. Laser cladding of WC-Co has constraints on its practical use because a clad bead of WC-Co often includes numerous defects such as cracks and pores. Various factors cause pores in clad beads. Therefore, establishing a method for restraining them is difficult. Obtaining dense clad beads having few pores requires the elucidation of behaviors of gas bubbles: the precursors of pores. Nevertheless, observations inside molten pools are difficult, thereby complicating the characterization of gas bubble behavior.