Effect of Carbon Addition and Sintering Temperatures on Densification and Microstructural Evolution of Sinter-Hardening Alloy Steels

The iron-copper-carbon alloys are used extensively in powder metallurgy due to their superior dimensional control; however, they possess lower mechanical properties, corrosion resistance and wear resistance than their wrought counter part.In recent years, there have been concerted attempts to engineer ferrous alloys with high dimension tolerance and enhanced mechanical properties.One such approach is to use prealloyed iron powder instead of pure iron, mixed with copper and carbon.SH737-2Cu-C is one such alloy.The present study focuses on the effect of carbon addition on diffusion of Cu in SH737 alloys system via microstructural studies.SH737-2Cu alloys were compacted, sintered and characterized.The materials were characterized according to their density, densification parameter, shape factor, and pore size distribution.The microstructural studies revealed bimodal pore distribution in the sample with no carbon, due to the presence of primary and secondary porosity.The shape factor distribution showed more roundedness in the case of carbon added alloys.The size of the primary pores depends on compaction pressure and powder size distribution.On the other hand, size and morphology of the secondary pore strongly depends on Cu powder size, its homogeneity and sintering temperature.Also, an increase in the sintering temperature increased the roundedness and the pores became coarser.