The Influence of Holding Time to Mechanical Properties of Steel Processed with Powder Metallurgy

Abstract Steel with very small grain has high strength but still have ductility. Heating the steel until reach to austenite temperature can make the grain of the steel will growth and reduce the hardness of the steel, to prevent this it is necessary to know the effect of holding time on steel hardness. The hardness is indicating of grain growth of the steel. In this research, we investigated the effect of holding time to the hardness of very small-grained steel. Heat treatment was done at 1100 °C using an electric furnace. Micro-hardness testing used a micro-Vickers method using 300 gram forces and indentation time 10 minutes. Microstructure observation was done with metallurgical microstructure. The etching solution for microstructure observation was nital solution. The heat treatment process of steel powder metallurgy with a holding time of 60 minutes will cause hardness to decrease from 245 in holding 15 minutes to 207 and grain size grow from 1 µm to 4 µm.