Laser cladding of TiC reinforced 316L stainless steel composites: Feedstock powder preparation and microstructural evaluation

Abstract

Laser cladding was used to fabricate 316L/TiC composite coatings after optimizing the feedstock powder morphology. Firstly, the influences of ball-to-powder ratio (BPR) and milling duration on the morphology were investigated. The BPR of 1: 1 and 2 h of milling was sufficient to attach considerable amount of TiC particles onto 316L particles. Then, the microstructure and hardness behaviors of 15 vol% TiC reinforced 316L coatings were examined. Partial or total dissolution of the original TiC powders led to the formation of a reinforced austenitic microstructure with a hardness increase of 100 HV. This increase is due to a grain refinement effect of the TiC during solidification and the presence of new solidification carbides. Partially dissolved and primary MC globular carbides are well-distributed in the matrix together with few larger MC globular carbides. Furthermore, MC coral-like pseudo-primary carbides and MC branched eutectic carbides are observed inside the cells and in intercellular spaces, respectively.