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Microstructural Effects on the Toughness of a High Co–Ni Steel
Author(s) -
Gruber Marina,
Ressel Gerald,
Ploberger Sarah,
Marsoner Stefan,
Kolednik Otmar,
Ebner Reinhold
Publication year - 2017
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201600633
Subject(s) - austenite , tempering , materials science , metallurgy , toughness , fracture toughness , martensite , diffusionless transformation , thermal stability , cryogenic treatment , composite material , microstructure , physics , quantum mechanics
Purpose of this work is to investigate the effects of reverted and retained austenite on the fracture toughness of high Co–Ni steels. Different cryogenic and tempering treatments are applied to a high Co–Ni steel in order to alter the austenite content, its chemical composition and hence its stability against transformation to martensite. Austenite stability is analyzed by applying thermal cycles in the dilatometerand by X‐ray diffraction. For each heat treatment, the fracture toughness is characterized by J‐integral and fractographic crack growth resistance measurements. The results indicate that cryogenic and two‐step tempering treatments lead to a higher austenite stability and impede austenite transformation during cooling after tempering. Consequently, the toughness is considerably improved.