• CN：11-2187/TH
  • ISSN：0577-6686
机械工程学报

机械工程学报 ›› 2015, Vol. 51 ›› Issue (6): 2-8.doi: 10.3901/JME.2015.06.002

• 压力容器专栏 •    下一篇

热输入对2.25Cr1MoV钢粗晶热影响区再热裂纹敏感性的影响

韩一纯1, 2 陈学东2 范志超2 卜华全2

  1. 1.中国科学技术大学近代力学系;
    2.合肥通用机械研究院
  • 出版日期:2015-03-20 发布日期:2015-03-20
  • 基金资助:
    国家重点基础研究发展计划(973计划，2012CB626813)和国家高技术研究发展计划(863计划，2012AA040103)资助项目

Influence of Weld Heat Inputs on Reheat Cracking Sensitivity of Coarse-grained Heat Affected Zones in 2.25Cr1MoV Steel

HAN Yichun1, 2 CHEN Xuedong2 FAN Zhichao 2 BU Huaquan2   

  1. 1. Department of Modern Mechanics, University of Science and Technology of China, Hefei 230026;
    2. Hefei General Machinery Research Institute, Hefei 230031
  • Online:2015-03-20 Published:2015-03-20

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摘要： 再热开裂曾多次在2.25Cr1MoV钢反应器的焊接粗晶热影响区(Coarse-grained heat affected zone, CGHAZ)部位发生，却很少在“斜Y型坡口再热裂纹试验”中出现。考虑两者之间的热输入差异，通过Gleeble热模拟试验研究热输入对2.25Cr1MoV钢CGHAZ再热裂纹敏感性的影响，并结合显微组织观察、硬度测定及断口分析，讨论热输入、组织和性能之间的关系。结果表明，在5～100 kJ/cm的热输入范围内，CGHAZ的再热裂纹敏感性随热输入的升高而增大，当热输入为35 kJ/cm时，CGHAZ在675 ℃对再热开裂“高度敏感”，限制热输入在25 kJ/cm以内，将有效降低其再热裂纹敏感性。综合分析发现，模拟CGHAZ的高温塑性与其在高温拉伸试验后硬度的变化规律之间存在良好的对应关系。当软化现象发生时，拉伸试样的断裂模式为穿晶与沿晶的混合型断裂，具有较高的断面收缩率(Reduction of area, RoA)，当二次硬化现象发生时，其断裂模式为均一的微孔聚集型沿晶断裂，RoA显著降低。试验结果从二次硬化的角度反映了高热输入条件下CGHAZ的再热脆化机理。

关键词: 2.25Cr1MoV钢, 焊接粗晶热影响区, 热模拟, 再热裂纹敏感性

Abstract: Reheat cracks have been detected many times in the welding coarse-grained heat affected zones(CGHAZ) of 2.25Cr1MoV reactor, but seldom been discovered after Y-groove reheat cracking test. Considering the difference of heat inputs between the two, the influence of weld heat inputs on reheat cracking sensitivity of CGHAZ in vanadium-modified 2.25Cr1Mo are studied by mean of Gleeble thermal simulation. Effect of heat inputs on microstructural, hardness, and high temperature ductility are discussed by microstructural observation, hardness test and fractographic analysis. The results show that the reheat cracking sensitivity of CGHAZ increases with increasing heat inputs within the range of 5～100 kJ/cm. CGHAZ with heat input of 35 kJ/cm is considered “highly susceptible” to reheat cracking at 675 ℃. The reheat cracking sensitivity is mitigated effectively by heat inputs limited to 25 kJ/cm. The comprehensive analysis reveals that the high temperature ductility of the simulated CGHAZ is closely related to the hardness change after high temperature tensile test. Relatively high reduction of area(RoA) is observed corresponds to softening phenomena, along with a mixed fracture mode of transgranular and intergranular. While the ductility of CGHAZ degraded obviously when second hardening occurs, along with a uniform fracture mode of intergranular microvoid coalescence.

Key words: 2.25Cr1MoV steel, reheat cracking sensitivity, thermal simulation, welding coarse grained heat affected zones

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