Effect of Nano-Scale Copper Sulfide Particles on the Yield Strength and Work Hardening Ability in Strip Casting Low Carbon Steel

Abstract

Direct near net shape casting is an attractive process for the production of sheet metal because of its economical profit and the production of a new microstructure due to the fast solidification rate. To explore further advantages of direct near net shape casting, the differences in the mechanical properties between the as-cast and annealed strips of a steel with comparatively high contents of the impurities (Cu, P and S) were investigated in this paper with an emphasis on the microstructural effects. This process not only produced fine microstructures but also resulted in nano-scale copper sulfides. The as-cast strip has higher yield and tensile strengths and maintains high work hardening ability at higher stress levels than that of the annealed strip. Both the as-cast and annealed strips have a superior balance of strength and work hardening ability compared to the strips without the impurities. The nano-scale copper sulfide particles in the as-cast strip contributed most to the increase in the yield strength. The as-cast strip also could not produce the good work hardening ability without the nano-size particles. Further improvements in strength and work hardening ability can be attained by controlling the particles' size and the volume fraction in the strip.