Influence of Nb on microstructure and mechanical properties of 0.2C-1.5Si-1.8Mn quenching and partitioning steel

doi:10.13251/j.issn.0254-6051.2020.03.015

Abstract

Abstract:

Based on traditional C-Si-Mn Q&P steel, the influence of niobium (Nb) on microstructure and properties of quenching-partitioning steel (Q&P) was investigated by adding moderate microalloying element Nb. The results show that the microstructure of the Nb-added steel consists of ferrite, lath martensite and M/A island, basically being the same as that of Nb-free steel. However, the martensite lath of the Nb-added steel is obviously refined, and the inter-lath spacing is significantly reduced. The addition of Nb promotes the precipitation of ferrite, inhibits the formation of pearlite, thus effectively refines the microstructure and shortens the carbon partitioning distance, facilitates the diffusion of carbon into austenite and increases the stability of austenite. The yield strength and tensile strength of the Nb-added steel are improved after the same Q&P heat treatment, with the tensile strength and elongation reaching to 989.07 MPa and 18.36% respectively, the production of tensile strength and plasticity reaching up to 18.16 GPa·%.

Key words: quenching and partitioning steel, microalloying element Nb, microstructure, diffusion, mechanical properties

CLC Number:

TG142.1

Zhan Hua, Leng Deping, Pan Hongbo, Xiao Yangyang, Liu Yonggang, Cao Jinghua. Influence of Nb on microstructure and mechanical properties of 0.2C-1.5Si-1.8Mn quenching and partitioning steel[J]. HTM, 2020, 45(3): 73-77.

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