Evaluation of Microstructure and Wear Behavior of Iron based Hard facing Coatings on the Mo40 Steel

Mo40 low alloy steels are mostly used to produce industrial components such as crane wheels whichare exposed to abrasive wear. However, during working conditions, their wear resistance is reduced aftera while due to its low hardness. With increasing abrasive wear, the dimensions of components decreaseand they need to be repaired for surface modification. In this regard, hard overlay coatings are applied byhard facing process for reusing these components. This work deals with the surface analysis, hardnessand wear behaviors of the clad layers made of the Fe Cr C based hard facing on the Mo40 low alloysteel by submerged arc welding method. The overlay coatings are performed by two ways of welding:1. rods of UP6 GF 50 (307 kavosh joosh standard number), and 2. UP6 GF 50 C (420 kavosh jooshstandard number) regarding the Din 8555 standard, in single and double passes. According to the X raydiffraction analysis and microstructure characteristics, both martensite with retained austenite phasesand the (Fe, Cr)23 C6 carbides were identified within the overlay coatings. The presence of the carbonand chromium elements in hard surfaced specimens (as denoted by 307 and 420) produced by single anddouble pass were increased. The wear resistance in the coatings of 307 and 420 produced by double passare higher than the coatings produced by single pass. In addition, the amount of average hardness in thecoatings of 307 and 420 produced by single and double passes increases from 36 to 38 HRC and from 39to 42 HRC, respectively. Based on the scanning electron microscopy micrographs, the wear mechanismsof specimens with high hardness are adhesive and tribochemical wear.