Findings of grain coarsening temperature and grain growth of light weight steel used in automotive industry

Abstract

Efforts have been made in this research and experimental work to observe the grain coarsening temperature (GCT) by keeping in view the formation of second phase particles. Four steels having different chemical compositions were heat treated at series of temperatures i-e 850°C, 925°C, 1000°C, 1100°C and 1175°C with holding time of 1 hour and 2 hours respectively. After heat treatment traditional method of grinding and polishing was applied to reveal the microstructure. Grain size distribution at each temperature was calculated by using matrox inspector and the result was plotted with origin data analysis software. It was found that presence of second phase particles can affect the grain growth phenomena in the experimental steels and also grain growth have consequences on grain coarsening temperature on the steel under investigation. Steel A (Nb-Al) showed the finest grain structure, Grain size of steel B (Nb) was slightly higher than that of steel A. In steel C (Al), AlN particles did not exist. The only particles present were of TiN. Hence, the mean grain size of steel C was higher than that of steel A and steel B.