Effect of C, N contents on microstructure and properties of 12%Cr ferritic heat resistant steel

doi:10.13251/j.issn.0254-6051.2024.12.028

Abstract

Abstract: Effect of C and N contents on microstructure and mechanical properties of 12%Cr ferritic heat-resistant steel was studied by observing the microstructure and tensile tests at room temperature and high temperature of three groups of 12%Cr ferritic heat resistant steel with different C and N contents. The results show that when the C content increases from 0.14% to 0.20%, the size of martensite laths decreases, δ-ferrite disappears, and the effect of martensite lath refinement improves the strength of the steel. When the N content increases from 0.004% to 0.02%, the prior austenite grain size and martensite lath width decrease, and the number of MX precipitates in the laths increases. The solution strengthening and the second phase strengthening enhance the strength of the steel, while the δ-ferrite reduces the strength, and the change of C and N contents has little effect on the plasticity. According to production practice, when the C content is reduced to 0.14% and the N content is controlled at 0.02%, the tensile properties of the tested steel is optimal. The yield strength, tensile strength and elongation at room temperature are 573.5 MPa, 763.0 MPa, and 24%, respectively. When the tensile test temperature is 550 ℃, the yield strength, tensile strength, and elongation are 344.5 MPa, 414.0 MPa, and 34%, respectively.

Key words: C content, N content, 12%Cr ferritic heat resistant steel, microstructure, tensile properties

CLC Number:

TG142.1

Ma Tingwei, Hao Xianchao, Wang Ping, Zhu Jingyi. Effect of C, N contents on microstructure and properties of 12%Cr ferritic heat resistant steel[J]. Heat Treatment of Metals, 2024, 49(12): 169-174.

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