Metalografi Transformasi Baja Mangan (Fe Mn) pada Kondisi Pendinginan Media Udara

Abstract

Hadfield steel used for railroad tracks was investigated for microstructural changes due to an aging treatment regime. The steel was subjected to solution treatment by heating at a temperature of 1000°C-1090°C and then water quenched. The as-quenched material was then investigated for the development of microstructure in an aging treatment by heating at various temperatures (400°C, 450°C, 500°C, 550°C and 600°C) and at two holding times (30min, 60min). The ensuing microstructure was then examined for morphology using Optical Microscopy and X-ray fluorescence spectroscopy (XRF) for element constant. Results of the morphological mapping showed that at lower temperatures, ferrites grow in the form of sheaves of parallel plates which nucleated at austenite grain surfaces. At a higher temperature, the ferrites gave way to acicular ferrite plates, growing in many different directions. A new phase was formed in the 400°C to the 550°C which was confirmed as to be the transformation amorph bainite to the accicular bainite. The upper threshold for pearlite formation was at 600°C when again the ferritic structure was observed.