Effect of long-term aging on microstructure and properties of 21-4NWNb steel

doi:10.13251/j.issn.0254-6051.2024.07.012

Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (7): 78-83.DOI: 10.13251/j.issn.0254-6051.2024.07.012

• MICROSTRUCTURE AND PROPERTIES • Previous Articles Next Articles

Effect of long-term aging on microstructure and properties of 21-4NWNb steel

Zhao Shouzhong, Wang Shouqian, Zhu Zhiyuan, Min Liang, Xu Chaofan, Shen Jiabao

School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang Jiangsu 212000, China

Received:2024-01-30 Revised:2024-05-06 Online:2024-07-25 Published:2024-08-29

Abstract

Abstract: Microstructure evolution and mechanical properties change of the 21-4NWNb steel after standard heat treatment (1050 ℃×30 min+750 ℃×4 h) during long-term aging at 750 ℃ were studied. The results show that the grain size of 21-4NWNb steel does not change obvious during long-term aging. When aged for 200 h, a small amount of regular block M₂₃C₆ carbides are distributed in the steel. When the aging time extends to 500 h, σ phase (AB) gradually appears in the grain. The hardness of the 21-4NWNb steel reaches the highest value of 324 HV when aged for 200 h with a maximum tensile strength of 971 MPa and a elongation of 22.2%. With the prolong of aging time from 200 h, the hardness and tensile strength show a gradual decline, and the elongation of the steel drops below 15% after aging for 2000 h.

Key words: 21-4NWNb steel, long-term aging, σ-phase

CLC Number:

TG156.1

Zhao Shouzhong, Wang Shouqian, Zhu Zhiyuan, Min Liang, Xu Chaofan, Shen Jiabao. Effect of long-term aging on microstructure and properties of 21-4NWNb steel[J]. Heat Treatment of Metals, 2024, 49(7): 78-83.

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Effect of long-term aging on microstructure and properties of 21-4NWNb steel

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