Microstructure and wear characteristics of high-carbon Cr-based alloy claddings formed by gas tungsten arc welding (GTAW)

Abstract

High-carbon Cr-based alloy claddings with distinct carbon contents are fabricated on medium-carbon steel substrates by the GTAW process utilizing various pure Cr and CrC (Cr:C = 4:1) alloy fillers. The results show that the microstructures of hypoeutectic, near-eutectic, and hypereutectic structures with various proeutectic Cr-Fe phases, (Cr,Fe)(23) C(6) and (Cr,Fe)(7) C(3) carbides, form in the coated surface depending on the carbon contents. The wear resistance is determined by the type, mechanical properties, and volume fraction of pro-eutectic phases, as well as by the matrix microstructure. The cladding with 2.3%C possesses the worst wear resistance, which can be attributed to great amounts of soft pro-eutectic Cr-Fe phases. The cladding with 5.9%C has the best wear resistance. The improvement of wear resistance results from the high volume fraction of hard and wear-resistant pro-eutectic (Cr,Fe)(7) C(3) carbides, which are distributed homogeneously in the fine and strong [alpha + (Cr,Fe)(7) C(3)] eutectic colonies. (C) 2010 Elsevier B.V. All rights reserved.