Evaluation of microstructure and mechanical properties of Al-Cr/Al2O3 claddings produced by GTAW process

In this research, the cladding process was done using the mechanically alloyed Al-Cr and Al-Cr2O3 powder mixtures by GTAW process on the surface of CK45 steel. After creating the AlCr2 and AlCr2-Al2O3 surface layers, the microstructural and microhardness of the claddings were studied by optical microscopy, scanning electron microscopy and microhardness measurements. In order to evaluate the wear resistance of the claddings, pin-on-disk wear test was done. It was found that after 20 h of MA of Al-Cr powder mixture, Cr(Al) solid solution was formed. XRD analysis of created cladding by this powder mixture indicated the formation of AlCr2 phase. Also the cladding of Al-Cr2O3 powder mixture led to the formation of AlCr2 and Al2O3 phases. The microhardness of both claddings was higher than the base metal. Also the microhardness of AlCr2-Al2O3 cladding reached to about 780 HV. The predominant wear mechanism in wear test of both claddings was micro-cutting abrasive wear. The wear weight loss of AlCr2 cladding was about 0.2 mg, while AlCr2-Al2O3 cladding did not show any weight loss. The friction coefficient of AlCr2-Al2O3 cladding after 200 m of sliding distance was about 0.15 which reached to about 0.35 at longer sliding distances. This increase in friction coefficient of this cladding as compared with AlCr2 cladding was related to the presence of Al2O3 hard particles in this cladding.