Coating of AISI 4340 low-alloy steel with austenitic stainless steels and stellite6 cobalt base by tungsten-gas arc welding method and investigation of the microstructure and wear behavior of the resulting layer

is In this research, the microstructure and wear behavior of high-strength AISI 4340 low-alloy steel coated using austenitic stainless steels ER309, ER312 and cobalt base steel stellite 6 were investigated by tungsten-gas arc welding method. Microstructural investigations were carried out by optical microscope and scanning electron microscope equipped with X-ray energy diffraction spectroscopy system.Hardness measurement was done by Vickers method with a load of 30kgf on the surfaces and Vickers microhardness in the transverse sections of the welds in zigzag form. Also, in order to evaluate the wear behavior, the wear test of the pin on the disc was used to identify the wear mechanism. By reducing the intensity of the current in the second layer and also by increasing the number of welding layers, the dilution and mixing of the sub-layer decreased and the hardness increased, and the highest hardness was 565 (HV) for stellite6. The results of the wear test showed that the highest friction coefficient was related to ER 309 weld metal has an average value of 0.68 and the lowest friction coefficient is related to stellite 6 weld metal with an average value of 0.53.