Evaluation Microstructure and Hardness of the Fe-Cr-C Hardfacing Alloy with Cr/C=6 Ratio

In this investigation, different amount of carbon and chromium content of Fe-Cr-C hardfacing alloys with the constant ratio of Cr/C=6 were used. These alloys were fabricated by GTAW on AISI 1010 mild steel substrates to achieve hypo/eutectic/hyper compositions. OES, XRF, OM, SEM, XRD techniques and HV method were used for determining chemical composition, hardness and studying the microstructure of hardface alloys. The metallographic examination results indicated that all hardface samples had three metallurgical zones with different thickness, microhardness, chemical composition and solidification modes. The microstructures of all hardface samples in thicker Zone consists of austenite and chromium-iron carbides (Cr,Fe)7C3. Moreover with increasing of carbon and chromium content of thicker zone in hardface samples, the volume fraction of (Cr,Fe)7C3 increased and resulted in the decreasing of austenite volume fraction and increasing hardness of the top surface. A multiple regression model was used to determine the relation between microstructure, chemical composition and hardness.