Microstructure and Mechanical Properties of A283 Steel Coated by Inconel 625 and 347 Steel Using GTAW

In this research, the effect of double layer cladding on the microstructural and mechanical properties of A283 steel substrates has been studied. In this regard, 347 stainless steel and Inconel 625 were selected as filler rods and GTAW was used for the coating process. Microstructure and mechanical properties of the resulted coating were then examined. Microscopic observations revealed that, due to the high solidification rate, a columnar dendrite microstructure was formed, where a single layer of coating was applied. The columnar dendritic morphology of the first layer was converted to island state and acicular dendrites after applying the second layer. EDS analysis confirmed the presence of carbides in both coating layers. The results of line scan analysis indicated a mild slope in the changes of the chemical concentration of the elements from the substrate to the 347 and then 625 coating layers. On the contrary, a noticeable change in the concentration of the elements was observed by applying a single layer of 625 alloy on the substrate, without the presence of 347 alloy as inter-layer. The results of hardness and wear tests showed that the highest hardness values and wear resistance belonged to the Inconel 625 coating. By applying Inconel 625 coating, hardness values and wear resistance were respectively increased up to ~ 41% and 3.5 times higher, when compared to the same values of A283 steel substrate. Also, applying the 347 coating caused an improvement of hardness and wear resistance to ~ 18% and 1.7 times higher, respectively.