Investigating the Effect of Tungsten Element on the Microstructure and Mechanical Properties of Fe-C-Ni Hard Coating

In this paper, the effect of tungsten element on microstructure and mechanical properties of Fe-C-Ni hard coating was investigated. Two hard coating electrodes were made with 10 and 30 gr of tungsten powder. The microstructure of the welding metals included fine carbides in the area of ​​needle martensite and residual austenite. Electron microscopy studies showed that there were very fine cracks in the weld metal martensitic phase with 10 gr of tungsten but these microscopic cracks were not found in weld metal with 30 gr of tungsten. The results of the EDS analysis showed that the amount of soluble tungsten element in the austenite phase of both welding metals is high. This amount in weld metal with 30 gr of tungsten was about 3.66% higher than the weld metal with 10 gr of tungsten. The results of the XRD analysis showed that the phases present in the weld metal with 10 gr of tungsten included martensite, austenite and W2C carbide, but in the weld metal with 30 gr of tungsten in addition to these phases also iron oxides were observed. The results of hardness test showed that the average hardness of weld metal with 10 gr of tungsten is 42.5 RC and the average hardness of welding metal with 30 gr of tungsten is 49.6 RC.