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Contrary Effects of Microstructure and Cleanliness on Tensile and Toughness Properties in Precipitation Hardening Stainless Steels
Author(s) -
Nick EvaMaria,
Müller Merle G. J.,
Voigt Sally G.,
Park Daesung,
Reinholdt Alexander,
Schwedt Alexander,
Weirich Thomas E.,
Bleck Wolfgang,
Münstermann Sebastian
Publication year - 2012
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.201100237
Subject(s) - materials science , microstructure , austenite , toughness , metallurgy , ultimate tensile strength , precipitation hardening , martensite , optical microscope , ferrite (magnet) , composite material , scanning electron microscope , precipitation , copper , physics , meteorology
A detailed microstructural analysis on two precipitation hardening steels of similar chemical composition and of identical heat treatment but with different microstructures and mechanical properties was performed to reveal the constituents that are of major importance for strength and toughness. Light optical microscopy, magnetic saturation measurements, energy dispersive X‐ray analysis, scanning and transmission electron microscopy were used to identify and quantify the internal cleanliness, the secondary phases (δ‐ferrite, retained austenite), and the copper‐rich precipitates. The high purity and homogeneity of the steel's microstructure proved to be beneficial for upper shelf toughness and general isotropic behavior. In contrast, good elongation depended on local element segregation, allowing the stabilization of austenite to ambient temperature. The precipitation of copper‐enriched inter‐metallic phase was documented both in the martensitic matrix and in the δ‐ferrite; it ensured – for given heat treatment – sufficient yield strength independent of other microstructural constituents.