The Mossbauer spectroscopy studies of epsilon to cementite carbides transformation during isothermal heating from as-quenched state of high carbon tool steel

This work presents results of investigations using the Mossbauer spectroscopy technique and their interpretation concerning transformation of ² to cementite carbides during tempering in relation to the previously conducted dilatometric, microscopic and mechanical investigations. Investigations were performed on 120MnCrMoV8-6-4-2 steel. The in°uence of the tempering time on nucleation and solubility of ² carbides, and on cementite nucleation and growth, was determined. The analysis of phase transformations during various periods of tempering using the Mossbauer spectroscopy technique made possible to reveal ¯ne details connected with the processes

A new XRD method to quantify plate and lath martensites of hardened medium-carbon steel

This paper introduces a new technique to separately measure the volume fraction and tetragonal ratio of co-existing lath and plate martensites in ultrahigh strength steel, and to calculate their different carbon contents. First of all, the two martensites are assumed to have body centre tetragonal lattice structures of different tetragonal ratios. X-ray diffraction is then applied to obtain the overlapping (200) diffraction peak, which is subsequently separated as four sub-peaks using a self-made multiple Gaussian peak-fitting method to allow the measurement of the individual lattice parameters c and a. Finally a modified equation is applied to calculate the carbon contents from the obtained tetragonal ratios. The new technique is then applied to investigate the effect of subsequent tempering on the decarbonisation of the as-quenched martensites. Keywords: Gaussian peak-fitting, martensite carbon content, martensite tetragonal ratio, medium-carbon steels, Xray diffractio