Heat Treatment of Metals ›› 2025, Vol. 50 ›› Issue (3): 174-182.DOI: 10.13251/j.issn.0254-6051.2025.03.028

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Fatigue crack propagation rate of high temperature resistant martensitic steel for pressure vessel

Yang Hao1, Zhang Hongtao2, Liang Enpu1, Xia Mingqi3, Shi Chao4, Xu Le1, Liu Xin1, Wang Maoqiu1   

  1. 1. Research Institute of Special Steels, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China;
    2. North Hua'an Industrial Group Co., Ltd., Qiqihar Heilongjiang 161000, China;
    3. Army Equipment Department in Shenyang Regional Military Representative Bureau in Baotou Regional Situation Representative Office, Baotou Inner Mongolia 014000, China;
    4. Inner Mongolia North Heavy Industry Group Co., Ltd., Baotou Inner Mongolia 014000, China
  • Received:2024-12-30 Revised:2025-01-27 Online:2025-03-25 Published:2025-05-14

Abstract: Tensile and fatigue crack growth tests were conducted on high temperature martensitic steels PCrNi3MoV, 25Cr3Mo3NiNbZr and 20CrNiMo2VNb at 25 ℃ and 700 ℃ to investigate the fatigue crack growth behavior of pressure vessel steels, respectively. The results show that at room temperature, the strength of the three tested steels is fairly the same. When the stress intensity factor level (ΔK) is 60 MPa·m, the fatigue crack growth rates (da/dN) are 1.05×10-3, 8.80×10-5, and 7.73×10-5mm/cycle, respectively. The fatigue crack growth rate of the 20CrNiMo2VNb steel at room temperature is the lowest, which is attributed to its largest proportion of substructure high-angle grain boundaries, reaching 81.46%. At 700 ℃, when the stress intensity factor level ΔK is 30 MPa·m, the fatigue crack growth rates of the three tested steels are 1.58×10-3, 3.78×10-4, and 3.89×10-5mm/cycle, respectively. Through the comparative analysis of the microstructure and high temperature strength, it is found that the highest tensile strength of the 20CrNiMo2VNb steel at 700 ℃ is the main reason for its low fatigue crack growth rate. Based on the Paris model, a quantitative relationship between the fatigue crack growth rate and mechanical properties of high temperature resistant martensitic steel is established, which provides theoretical support for the subsequent research on the fatigue crack growth of the 20CrNiMo2VNb steel.

Key words: high temperature resistant martensitic steel, fatigue crack growth rate, Paris curve, stress intensity factor

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