Effect of Al, Ni, Mo, Ti, Nb and temperature on grain size number in low carbon high alloyed steel

Abstract

Usually steels for manufacturing are purchased on the basis of chemical composition. This can affect its properties. In this study chemical composition and temperature effect on grain size number has been observed carefully. Three steels with different chemical composition as well as heat treatment temperatures at 920°C and 1100°C respectively with holding time of 30 minutes in the oxidization atmospheric laboratory based furnace, to know the influence of both factors composition and temperature, microstructures of these three different steels have been obtained by conventional metallography methods. Grain size of each steel sample has been calculated as indicated by Higginson, R.L. and Sellars C.M. The ASTM grain size number. The data has been plotted at both observing temperatures. In the light of above experiments and observations it was concluded that chemical composition and temperature has definitely effect on ASTM grain size number. Al, Ni, Mo, Ti, Nb has significant effect on forming the microstructure and grain size can be affected by the presence of these elements in the steel composition. Also as the austenizing temperature is increased the grain size number is decreased. Aluminum can hinder the grain growth and nickel is austenite stabilizing element which can affect the grain size number.