Heat Treatment of Metals ›› 2024, Vol. 49 ›› Issue (2): 208-214.DOI: 10.13251/j.issn.0254-6051.2024.02.033

• PROCESS RESEARCH • Previous Articles     Next Articles

Effect of tempering time on microstructure and mechanical properties of Cr-Ni-Cu high strength steel for ships

Dong Xinxin1, Wu Jing1, Li Menghuan2, Tian Yaqiang2, Tang Qin3   

  1. 1. Department of Materials Engineering, Tangshan Vocational and Technical College, Tangshan Hebei 063000, China;
    2. Key Laboratory of the Ministry of Education for Modern Metallurgy Technology, North China University of Science and Technology, Tangshan Hebei 063210, China;
    3. Hot Rolling Department, Shougang Jingtang United Iron and Steel Co., Ltd., Tangshan Hebei 063200, China
  • Received:2023-08-20 Revised:2023-12-29 Online:2024-03-27 Published:2024-03-27

Abstract: The microstructure evolution and mechanical properties of Cr-Ni-Cu high strength steel for ships after quenching and tempering were studied by means of SEM, EDS, mechanical test and low temperature impact test. The results show that after directly quenching and quenching at 900 ℃ for 30 min, both the microstructure is composed of lath martensite and retained austenite, but the low-temperature impact absorbed energy of the latter is higher than that of the former at -20 ℃ (56 J and 64 J, respectively), which is mainly attributed to the larger lath spacing of martensite. When tempered at 500 ℃ for 30, 60, 120, 240 and 480 min, the yield strength, tensile strength and low-temperature impact absorbed energy of the alloy steel show a trend of increasing first and then decreasing. The maximum tensile strength is 1021 MPa, the maximum yield strength is 998 MPa, and the maximum low-temperature impact absorbed energy at -20 ℃ is 86 J.

Key words: high strength steel for ships, heat treatment, lath martensite, retained austenite, mechanical properties

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