Selective laser melting of AISI 304 stainless steel composites reinforced by Al2O3 and eutectic mixture of Al2O3-ZrO2 powders

Abstract

The effect of Al2O3 and eutectic mixture of Al2O3–ZrO2 reinforcements on the densification, microstructural, and mechanical behaviors of selective laser melted 304 stainless steel composites have been investigated in this study. An optimum volume content was identified for the eutectic mixture of Al2O3–ZrO2 reinforcement, while the samples reinforced by Al2O3 particles exhibited a detrimental trend with increasing Al2O3 content. The addition of ZrO2 particles led to the formation of regular and even scanning tracks, whereas swelling of the molten tracks was observed due to the melting-point depression in addition to the low viscous melt pools and greater fluidity. Moreover, process-induced cracks and voids were observed in the samples reinforced by Al2O3, while the use of the eutectic mixture of Al2O3–ZrO2 was observed to suppress the cracks, leading to a dense structure. The microhardness of the fabricated samples reinforced with the eutectic mixture of Al2O3–ZrO2 particles was observed to be considerably higher than that of those reinforced with Al2O3 composites due to the homogeneous dispersion of the eutectic structures. The results of this study confirm that the use of a eutectic mixture of Al2O3–ZrO2 particles suppresses process-induced cracks and significantly enhances the reinforcing effect on 304 stainless steel composites.