Reheat cracking susceptibility of modified T23 steel

doi:10.13251/j.issn.0254-6051.2020.01.005

Abstract

Abstract: Microstructure of CGHAZ in T23 and four groups of modified T23 steel was investigated by means of optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Gleeble was used to produce the simulated coarse-grained heat-affected zone (CGHAZ) in T23 and four groups of modified T23 steel via thermal simulation of welding, and it was also used to evaluate the reheat cracking susceptibility by isothermal slow strain rate tensile test. The factors that influencing reheat cracking susceptibility were discussed, and the reasons for decreased reheat cracking susceptibility of modified T23 steel were analyzed. The results show that the grain size, intergranular precipitates, intragranular precipitates and solid solution elements have a significant influence on the reheat cracking susceptibility. Compared with T23 steel, the microstructure of modified T23 steel is optimized, leading to the decreased difference between intergranular strength and intragranular strength. Therefore, the reheat cracking susceptibility of modified T23 steel is improved.

Key words: modified T23 steel, reheat cracking susceptibility, Gleeble thermal simulation, coarse-grained heat-affected zone (CGHAZ), precipitates

CLC Number:

TG142.1

Zhou Renyuan, Zhu Lihui, Li Shixian, Zhai Guoli, Song Ming. Reheat cracking susceptibility of modified T23 steel[J]. HTM, 2020, 45(1): 20-25.

References

[1]瓦卢瑞克·曼内斯曼钢管公司. T23/T24管材手册-水冷壁和过热器用新材料[C]. 2005: 205-322.
Vallourec and Mannesmann Tubes. Handbook of T23/T24 Pipes-New Materials for Water Wall and Superheater[C]. 2005: 205-322.
[2]Masuyama F, Koyoyama T. Development of a tungsten strengthened low alloy steel with improved weldability[J]. Boiler Manufacturing, 1996.
[3]Viswanathan R, Nutting J. Advanced heat resistant steel for power generation[J]. San Sebastian, Spain, 1998: 27-29.
[4]王学, 李夕强, 杨超, 等. 超超临界锅炉水冷壁T23接头时效性能[J]. 动力工程学报, 2015, 35(4):325-330.
Wang Xue, Li Xiqiang, Yang Chao, et al. Aging properties of T23 weld joint in water wall of USC boilers, Journal of Chinese Society of Power Engineering, 2015, 35(4): 325-330).
[5]Park K, Kim S, Chang J, et al. Post-weld heat treatment cracking susceptibility of T23 weld metals for fossil fuel applications[J]. Materials and Design, 2012, 34: 699-706.
[6]Chang J C, Heo N H, Lee C H. Intergranular cracking susceptibility of 2.25Cr1.3W and 9Cr1MoVNb weld metals at elevated temperatures[J]. Metals and Materials International, 2010, 16(6): 981-985.
[7]Strader K, Alexandrov B T, Lippold J C. Stress-Relief Cracking in Simulated-Coarse-Grained Heat Affected Zone of a Creep-Resistant Steel[M]//Cracking Phenomena in Welds IV. Springer International Publishing, 2016.
[8]Heo N H, Chang J C, Yoo K B, et al. The mechanism of elevated temperature intergranular cracking in heat-resistant alloys[J]. Material Science and Engineering A, 2011, 528: 2678-2685.
[9]Li Y, Wang X, Wang J Q, et al. Stress-relief cracking mechanism in simulated coarse-grained heat-affectedz one of T23 steel[J]. Journal of Materials Processing Technology, 2019, 266: 73-81.
[10]金玉静, 周巍. 改良型T23钢CGHAZ再热裂纹开裂特征[J]. 金属热处理, 2017(11):197-203.
Jin Yujing, Zhou Wei. Characteristics of reheat cracking in CGHAZ of modified T23 steel[J]. Heat treatment of Metals, 2017, 42(11):197-203).
[11]Nawrocki J G, Dupont J N, Robino C V, et al. The stress-relief cracking susceptibility of a new ferritic steel-Part I: Single-pass heat-affected zone simulations[J]. Welding Journal Research Suppliment, 1999.
[12]Nakamura H, Naiki T, Okabayashi H. Stress-relief cracking in heat-affected zone[J]. Ishikawajima-Harima Research Institute Report, Tokyo, Japan, 1969.
[13]Indacochea J E, Kim G S. Reheat cracking studies on simulated heat-affected zones of CrMoV turbine rotor steels[J]. Journal of Materials Engineering and Performance, 1996, 5(3): 353-364.
[14]Vinckier A G, Pense A W. A review of underclad cracking in pressure-vessel components[J]. WRC Bulletin, 1974.
[15]金玉静. T23钢粗晶热影响区再热裂纹敏感性研究[D]. 上海: 上海交通大学, 2015.
Jin Yujing. Study on the susceptibility to reheat-cracking in the CGHAZ of T23 steel[D]. Shanghai: Shanghai Jiao Tong University, 2015.
[16]Vinckier A, Dhooge A. Reheat cracking in welded structures during stress relief heat treatments[J]. Journal of Heat Treating, 1979, 1: 72-80.