Effect of Heat Treatment on Fe–0.3%P–0.14%C Alloy

Abstract

Modern iron and steel industry is based on the iron – carbon diagram. However, a major problem associated with Fe-C alloys is that they corrode and cause losses to the tune of 5% of GDP to the world. Ancient Indian iron (Fe-P-C) artifacts like the Delhi Iron Pillar have withstood atmospheric corrosion for about 1600 years. Phosphorous and carbon are used as the alloying elements for strengthening iron and imparting corrosion resistance to it. Therefore, there is a need to understand the Iron-Phosphorous-Carbon alloy system and to develop strong and corrosion resistant, iron products. In the present study, Fe-0.3%P- 0.14%C alloy is subjected to heat treatment schedule by varying the rate of cooling after 30 minutes of heating at 800℃. Microstructural characterization is carried out on the heat treatment samples. The studies reveal a higher concentration of carbides in the form of pearlite formed at the grain boundaries of the ferrite grains in the air cooled samples. As per the literature, carbon pushes phosphorous from the grain boundaries to the grain interior by site competition. Micro-hardness studies on the test samples indicate that hardness of the phases formed at the grain boundaries is higher as compared to the hardness of the interior of the ferritic grains.