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The Influence of Holding Time on the Microstructure and Mechanical Properties of a 58CrMnSiNiMo Wear‐Resistant Cast Steel during Diffusion Annealing
Author(s) -
Pei Zhong-zheng,
Song Ren-bo,
Xu Jie,
Feng Yi-fan
Publication year - 2019
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.201900130
Subject(s) - materials science , lath , martensite , annealing (glass) , substructure , microstructure , toughness , metallurgy , ultimate tensile strength , composite material , austenite , structural engineering , engineering
The microstructure and mechanical properties of a 58CrMnSiNiMo wear‐resistant cast steel with or without diffusion annealing heat treatment are investigated. The results reveal a microstructural inhomogeneity and variation in the chemical composition of the steel without diffusion annealing, and the microstructural inhomogeneity is characterized by a dislocation substructure in the lath martensite and a twin substructure in the lenticular martensite. After diffusion annealing, the inhomogeneity is effectively reduced, and some complicated lath orientations are produced. With an increase in the diffusion annealing holding time, the average spacing of the martensite laths increases by 54.48%, with a value of 0.79 μm. After diffusion annealing, the second‐phase precipitates, mainly identified as M 7 C 3 and M 23 C 6 carbides, accelerate the division/formation of packet boundaries, block boundaries, and lath boundaries, and pin the packet boundaries and block boundaries. The diffusion annealing process significantly improves the ultimate tensile strength and toughness of the experimental steel from 1775 MPa and 44 J cm −2 to a maximum of 2029 MPa and 143.1 J cm −2 , respectively. After diffusion annealing, an increase in the toughness is attributed to high density dislocations in the martensite laths as well as thin lamellae of retained austenite between or around the corners of these laths.