Cast Austenitic Stainless Steel Reinforced with WC Fabricated by <i>Ex Situ</i> Technique

Abstract

In this study, the process of reinforcing austenitic stainless steel with tungsten carbide (WC) particles prepared by an ex situ technique was investigated. More specifically, the effect of microstructural features on the properties of the resulting WC-metal matrix composite (WC-MMC) was studied. For that purpose, porous Fe-WC preforms, prepared by the ex situ technique, were fixed in the mold cavity where they reacted with the molten steel. As confirmed by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), the resulting composite showed a compositional and microstructural gradient in depth. The microstructure next to the surface is essentially martensite with large WC particles. From this region to the base metal, the dissolution of the original WC particles increased, being closely related to the formation of new carbides: (Fe,W,Cr)6C, (Fe,Cr,W)7C3, and (Fe,Cr,W)23C6. At the interface bonding, a sound microstructure free of discontinuities was achieved. Furthermore, the mechanical tests indicated that the WC-MMC is four times harder and more wear-resistant than the base metal.

Keywords

• austenitic stainless steel
• <i>ex situ</i> technique
• metal matrix composite
• tungsten carbide