The effect of graphite shape on vacuum-free diffusion bonding of ST37 steel and nodular cast iron

Abstract

In this study, a low carbon steel (ST37) and tow kind of ductile cast iron with different nodularities, were diffusion bonded at the temperature 850 ۫C for 10 hours and then cooled in the furnace to investigate the effect of the graphite nodularity in the ductile cast iron on the diffusion bonding of dissimilar iron alloys and carbon diffusion. After diffusion bonding, microstructure analysis including metallographic examinations and image analysis, and also mechanical properties including microhardness measurements of interface region of the couples were made. The microstructure of the steel near the interfaces of couples consisted of peralite, but the amount of that is different in two couples. As a result, from the microstructure observations, the carbon diffusion to the steel from the ductile cast iron with 10% nodularity is higher than that with 90% nodularity, and a good bonding along the interfaces is formed.