Work

Effect of Induction Hardening Following Carburizing–Nitriding Duplex Treatment on the Microstructure and Fatigue Strength of JIS-SCM420 Low-Alloy Steel

Year: 2025

Type: article

Abstract: In this study, a duplex treatment combining carburizing, nitriding, and subsequent induction hardening (IH) was applied to JIS-SCM420 low-alloy steel. A comprehensive evaluation was conducted to assess surface characteristics, including microstructure, hardness, residual stress, and fatigue performance. The IH process successfully produced a high-nitrogen-content ε-Fe2-3(N,C) compound layer (2–3 μm thick) and fine acicular martensite at the surface, significantly enhancing surface hardness (950 HV0.03) and inducing beneficial compressive residual stress (−477 MPa). The IH-treated material exhibited a plane-bending fatigue strength of approximately 775 MPa, notably higher than that of conventionally carbonitrided specimens (700 MPa). This improvement was primarily attributed to the formation of the hard ε-Fe2-3(N,C) compound layer and refined martensitic structure resulting from induction hardening. Additionally, IH activated residual interstitial elements, promoting the precipitation of stable surface nitrides. These microstructural changes effectively suppressed fatigue crack initiation and propagation, thereby extending fatigue life under cyclic loading conditions.

Source: Metals

DOI: 10.3390/met15090944

Authors: Minheon Kim, Osamu Umezawa

Institution: Yokohama National University

Language: English

Topic: Surface Treatment and Residual Stress

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $3,137

Funders: Ministry of Education, Culture, Sports, Science and Technology, Japan Society for the Promotion of Science