Effect of Cr/C ratio on Microstructure and Thermal Fatigue life of the Fe-Cr-C Hardfacing alloy

In this Investigation two type of hard face coated electrodes (Fe-Cr-C) used as a hard facing alloys with different ratio Cr/C. The welding of hard facing electrodes were done in similar heat-input but in different of deposited layers on ST32 mild steel. The OES, OM, SEM and XRD techniques used for determining of chemical analysis and study of microstructure characteristics of hard face samples. In addition the thermal fatigue test were done at 600-25 OC for different samples and hardness test used for determining the hardness of hard face layers. The XRD examination Results indicated that microstructure of hard facing layer sample (AB electrode) includes primary carbides and eutectic (), the microstructure of hardfacing layer sample (SD electrode) includes austenite馪笢. The hardness result indicated that hardfacing samples (AB electrode) have maximum hardness which 52-58HRC and hard facing samples (SD electrode) with austenite martensite microstructure have minimum Hardness (30-50 HRC). The thermal fatigue Test results indicated, the highest fatigue life related to the sample that hard-faced with the SD electrode (Ø=4 mm) at a single layer and the lowest thermal fatigue life related to the sample that hard-faced with AB electrode (Ø=3.25 mm) at two layers. It was also found that there is an inverse relationship between hardness and thermal fatigue life of specimens.