The effect of pre-heat temperature on the microstructure and abrasive wear properties of laser metal deposited near-eutectic Fe-28Cr-2.9C alloy

Fe-Cr-C near-eutectic alloys are commonly used in wear resistant parts in mining applications, due to their excellent erosion and abrasion wear resistance. Laser metal deposition is an additive technology that presents opportunities for manufacturing mining components, as well as repairing worn areas of wear resistant parts. However, Fe-Cr-C hypoeutectic alloys are very hard and brittle and are often considered "unweldable"due to the lack of ductility required to accommodate thermal stresses. Therefore, controlling key processing parameters, such as preheating temperature and cooling rate, plays a crucial role in achieving crack-free layers with a refined microstructure. The aim of this study was to investigate the effect of substrate preheat temperature on the microstructure and wear properties of laser metal deposited Fe-28Cr-2.9C alloy. The microstructure and wear properties were analyzed for three different preheating conditions. The microstructure consisted of a near-eutectic structure consisting of M7C3 carbides + austenite, which has been mostly transformed to martensite. Increasing the preheating temperature increased the carbide size and retained austenite in the matrix, which was detrimental for the wear resistance.