Effect of solid-solution temperature on the microstructure and mechanical properties in low-cobalt secondary hardening ultra-high strength steel
Year: 2025
Type: article
Abstract: The effects of solid-solution temperature on the microstructure and mechanical properties of low-cobalt M 2 C and NiAl co-precipitated secondary hardening steel were investigated. With increasing solid-solution temperature, the microstructure undergoes complex evolution, characterized by an increase in retained austenite, dissolution of primary M 7 C 3 carbides, and growth of prior austenite grains. Correspondingly, the yield strength and impact toughness in both quenched and aged conditions initially improve. This is attributed to the dissolution of the primary M 7 C 3 carbides, which enhances the precipitation strengthening of M 2 C carbides and inhibits crack nucleation, thereby improving both strength and toughness. However, when the solid-solution temperature exceeds 900 °C, the coarsening of prior austenite grains leads to a reduction in Hall-Petch strengthening and decreased crack propagation resistance, resulting in a decline in yield strength and toughness in the aged state. The optimal solid-solution temperature is found to be 900 °C, where an excellent balance between strength and toughness is achieved.
Source: Procedia Structural Integrity
Authors: Haofei Zhu, Zhiping Xiong, Jianwen Mao, Xingwang Cheng
Institution: Beijing Institute of Technology
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4412436737