Effects of Chromium, Molybdenum and Vanadium on Spheroidization of Carbides in 0.8% Carbon Steel

Abstract

Synopsis Effecls of chro mium, moly'bdenum and vanadium on slJheroidi z alion of carbides in 0.8 0 a carbon sleel b)' slow cooling annealing have been inves-ligaled. An addilion of chromium remarkably accelerales spheroidiz alion of carbides, while addilions of molybdenum and vanadium do a lillie. X-ray' anal ,),sis of carbides indicates lhal M 3C and M,C 3 are only carbides observed lhrouglzoul lhe annealing IJrocess ill 2 0 0 and 5 '-;' chromium sleels, respeclively.. In molybdenum and vanadium sleels, however, car-bides formed b), lhe eu lecloid reaction are proved 10 differ from lhose surviving in auslenile on annealing, i.e., M 23 C. and M 3C are euleeloid carbides in moly'bdenum and vanadium sleels respectively, while tvlo 2 C and VC survive in auslenile in lhe sleels respeclively. Although lhe addilion of airy of lhese el~men ls results in increasing amounls of undis-solved carbides in auslenite, the facl thaI chromium has a marked effect on spheroidization of carbides strongly suggesls thaI an undissolved par-licle of carbides in au slenite of chromium sleels act as a cenler for the precipilalion of eulecloid carbides since undissolved carbides coincide with eulectoid carbides. Thu s il is concluded thaI coincidence of carbide precipilaling during eulectoid reaction with lhal surviving in auslenile will be of a primary importance in slJheroidiz alion of wlecloid carbides b), slow cooling annealing.