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Experimental Quantification of the Austenite‐ S tabilizing Effect of Mn in Cr M n N i As‐ C ast Stainless Steels
Author(s) -
Wendler Marco,
Mola Javad,
Krüger Lutz,
Weiß Andreas
Publication year - 2014
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201300271
Subject(s) - austenite , manganese , materials science , martensite , microstructure , phase diagram , diagram , metallurgy , nickel , analytical chemistry (journal) , phase (matter) , chemistry , mathematics , chromatography , statistics , organic chemistry
In this study, the austenite‐stabilizing effect of manganese in as‐cast Fe–(12–16)Cr–(0–13)Mn–6Ni (concentrations in wt%) stainless steels was investigated by means of light optical microscopy (LOM) and magnetic scale measurements. The well known Schaeffler‐diagram was used for the prediction of the microstructure at room temperature. Major deviations were observed between the Schaeffler‐diagram predictions and the experimentally determined phase fractions. Manganese contents above 2% were found to stabilize austenite more than expected on the basis of the Schaeffler‐diagram. To make that, the Schaeffler‐diagram matches the experimental observations using CrMnNi steels, the boundary between austenite and austenite + martensite regions, which denotes the beginning of the athermal martensite formation, must be displaced to lower nickel‐equivalents. Alternatively, the efficiency coefficient of manganese in the Ni‐equivalent formula can be increased which is preferred as it does not involve displacement of the boundaries in the Schaeffler‐diagram. The best match between observed microstructures and the Schaeffler‐diagram was obtained by defining the manganese efficiency coefficient in the Ni‐equivalent formula as a quadratic equation of the Cr‐equivalent.