In-situ development of Fe-Cr-C hardfacing layer using advanced submerged arc welding

Abstract Iron-based hardfacing is widely used to protect industrial equipment exposed to different types of wear. Welding is generally used in industry for producing these hardfacing layers since it gives better productivity as compared to other processes. The chemical composition of the deposited layer plays a significant role in controlling the mechanical and metallurgical properties. The present work aimed at developing an in-situ technique for employing a wear-resistant Fe-Cr-C hardfacing alloy on a mild steel base metal using the advanced submerged arc welding (ASAW) process. Alloying powders were used to introduce the alloying elements (primarily Cr and C) into the melt pool at the time of welding using three different powder and paste techniques and the element transfer behaviour was investigated. Alloying powders mixed with flux significantly increased the Cr content in the hardfacing. However, the amount of Cr and C present in the hardfacing deposited on consecutive runs varied significantly due to powder-flux separation owing to the large difference in density. On the contrary, the paste technique was observed to be the most effective alternative in terms of element transfer and compositional consistency of the developed hardfacing. Additionally, the effect of varying graphite content in the powder mix on the phase chemistry and microstructure was investigated. The microstructure was found to consist of a primary dendritic structure consisting mainly of austenitic phase. M7C3 and M23C6 type metal carbides were present in the inter-dendritic lamellar eutectic mix. Developed hardfacings exhibited significantly higher hardness values (up to 57 HRC) in contrast to base metal (80 HRB). Erosive wear test was also performed to study the wear performance of the deposited layer and the results indicated improved wear resistance of the deposited layer. SEM analysis of eroded surface was also performed to identify the erosion mechanisms.