Effect of Tempering Time on Microstructure and Mechanical Properties of SA738 Gr.B Steel

Abstract:

The effect of tempering time on the microstructure and mechanical properties of SA738 Gr.B nuclear power steel was studied using SEM, TEM and thermodynamic software, and its precipitation and microstructure evolution during tempering were clarified. The results showed that SA738 Gr.B nuclear power steel has better comprehensive mechanical properties after tempering at 650 °C for 1h. With the extension of the tempering time, M₃C transformed into M₂₃C₆ with increasing size, which affected the yield strength and impact energy. When the tempering time is 8h ~ 10h, due to the transformation of M₃C to M₂₃C₆, the composition of matrix around the carbide changed, causing the temperature of A_c1 dropped, forming twin-martensite which deteriorated the impact toughness of the steel.

• Periodical: Materials Science Forum (Volume 1016)
• Pages: 1739-1746
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1016.1739
• Online since: January 2021
• Authors: Yan Mei Li, Shu Zhan Zhang*, Zai Wei Jiang, Sheng Yu, Qi Bin Ye, Meng Qi Yang, Yan Hong Xi
• Keywords: Mechanical Properties, Phase Transformation, Precipitation, SA738 Gr.B, Tempering

References

[1] Information Office of the State Council of the People's Republic of China. China's Nuclear Security[N]. The People's Daily,2019-09-04(017).

[2] Yang, J., Wang, W.W., Qiu, S. Z., Tian, W. X., Su, G. H., & Wu, Y. W. . (2012). Simulation and analysis on 10-in. cold leg small break loca for ap1000. Annals of Nuclear Energy, 46(none), 81-89.

DOI: 10.1016/j.anucene.2012.03.007

[3] Hung, Z., Ferng, Y., Hsu, W., Pei, B., & Chen, Y. . (2015). Analysis of ap1000 containment passive cooling system during a loss-of-coolant accident. Annals of Nuclear Energy.

DOI: 10.1016/j.anucene.2015.06.027

[4] Yongzheng, Ma, Guang, Ran, Nanjun, & Chen, et al. (2016). Investigation of mechanical properties and proton irradiation behaviors of sa-738 gr.b steel used as reactor containment. Nuclear Materials and Energy.

DOI: 10.1016/j.nme.2016.07.010

[5] ASME, Boiler and Pressure Vessel Code. Section II, Part A, SA-738/SA-738M Specification for Pressure Vessel Plates, Heat Treated, Carbon-manganese-silicon Steel, for Moderate and Lower Temperature Service, ASME, (2001).

DOI: 10.1520/a0738_a0738m-03a

[6] Qibiao, H. , Shanyu, J. , & Weihua, S. . (2014). Study on heat treatment process of sa738gr.b steel plats for nuclear power plant. Shandong Metallurgy.

[7] Lisha, S.. (2015). Microstructure and security analysis of steel used for nuclear power plant with heat treatment. Foundry Technology.

[8] Bi, Z. C., Zhang, J. M. , Liu, X. D. , Jiang, S. Y. , & Sun, W. H. . (2011). Microstructure and mechanical properties of q and t heavy plate for nuclear power station purpose. Journal of Iron and Steel Research, 23(10), 59-62.

[9] Zhang, Y. L., & Hui, H. . (2019). Investigation of mechanical properties and ductile-brittle transition behaviors of sa738gr.b steel used as reactor containment. Key Engineering Materials, 795, 66-73.

DOI: 10.4028/www.scientific.net/kem.795.66

[10] GB/T 228-2010, Metallic Materials-Tensile Testing-Part 1: Method of Test at Room Temperature. Beijing, China, (2011).

[11] Jiang, Z., Wang, P., Li, D., & Li, Y.. (2015). Effects of tempering temperature on the microstructure and mechanical properties of granular bainite in 2.25cr-1mo-0.25v steel. Acta Metallurgica Sinica -Chinese Edition-, 51(8), 925-934.

[12] Lan, L. Y., Qiu, C. L., Zhao, D. W., Gao, X. H. , & Du, L. X. . (2011). Effect of austenite grain size on isothermal bainite transformation in low carbon microalloyed steel. Materials Science and Technology, 27(11), 1657-1663.

DOI: 10.1179/1743284710y.0000000026

[13] Skogsmo, J., & Atrens, A.. (1994). Analytical electron microscopy of grain boundaries in high-strength steels. Acta Metallurgica et Materialia, 42(4), 1139-1146.

DOI: 10.1016/0956-7151(94)90130-9