Microstructural analysis and mechanical properties of a dissimilar material of AISI 4130 steel substrate coated with Stellite 6 manufactured by transferred ARC plasma welding (PTA)

Abstract

This work evaluated the effect of varying PTA welding parameters on dilution: microstructure, microhardness, hardness and wear resistance. Two medium-carbon, low-alloy, high-strength alloy steel tubes, AISI 4130, were coated with CoCrWC cobalt alloy (Stellite 6) by powder-fed transferred arc plasma (PTA) welding process. Two different conditions were analyzed, varying the welding current, being 90A for condition 1 and 109A for condition (2). Appropriate specimens were removed for carrying out the metallographic tests, and microhardness, hardness and resistance to wear values were analyzed. abrasive wear. The samples were metallographically prepared for evaluation of the weld bead and the coating phases, through analyzes using SEM, EDS and X-ray diffraction (XRD). Rubber wheel abrasion tests were carried out following the ASTM G65 standard. It was observed that condition (2), with the lowest hardness value, highest dilution and a lowest volumetric fraction of carbides, presented a higher rate of wear, with its coating worn to the point of exposing the base metal after the test, when compared to condition (1), which presents a higher volume fraction of carbide phases, lower level of dilution and higher hardness.