Effect of the Number of Welding Passes on the Microstructure and Wear Behavior of St52 Plain Carbon Steel Coated with a High ChromiumCarbon Electrode

This study investigated the effect of the number of welding passes on the microstructure, hardness, and wear behavior of St52 plain carbon steel coated with an E10UM60R electrode in accordance with the DIN 8555 standard using SMAW method. An optical microscope (OM) and a scanning electron microscope (SEM) were used, and an EDS analysis was carried out to examine the microstructure. The Vickers micro hardness test and a reciprocating wear test were also used to examine the hardness and wear resistance. The results showed that the structure on the surface of the coated specimens is consisted of M7C3 carbides in the eutectic field (). In addition, the volume fraction of carbides increased in specimens that underwent two passes of welding relative to that in one passwelded specimen. The reason for this was related to the decreased dilution of iron and increased dilution of chromium in the twopass welded specimen and an increase in the volume fraction of M7C3 carbides. The increased percentage of carbides in the twopass welded specimen increased the hardness and consequently the wear resistance relative to those in the onepass welded specimen in a way that the surface hardness and weight loss in the wear test reached from 780 HV and 3.7 mg in the onepass welded specimen to 910 HV and 2.5 mg in the twopass welded specimen. Moreover, examining the wear surfaces indicated the occurrence of an adhesive wear mechanism in the specimens in a way that the adhesive wear rate decreased in the twopass welded specimens.