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| 冷速对厚壁X80三通焊缝组织及性能的影响 |
| Effects of Quenching Cooling Rates on Microstructure and Properties of X80 Pipe Fitting Welds |
| Received:November 20, 2019 Revised:January 10, 2020 |
| DOI：10.3969/j.issn.1674-6457.2020.01.020 |
| 中文关键词: X80三通 淬火处理 显微组织 力学性能 |
| 英文关键词: X80 pipe fitting quenching treatment microstructure mechanical properties |
| 基金项目: |
| Author Name | Affiliation | | LI Sheng | 1. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China | | NIU Jing | 1. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China | | YIN Xian-qing | 1. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China | | ZHANG Jian-xun | 1. State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China | | LIU Ying-lai | 2. CNPC Petroleum Pipe Engineering Technology Research Institute, Xi'an 710077, China | | FENG Yao-rong | 2. CNPC Petroleum Pipe Engineering Technology Research Institute, Xi'an 710077, China |
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| 中文摘要: |
| 目的 研究热成形后的厚壁X80三通整体淬火处理对焊缝组织和性能产生的重要影响。方法 对其淬火过程进行了热场的有限元计算，并根据计算结果进行热模拟试验，分析研究埋弧焊缝在不同冷却速度下的组织和性能。结果 在910 ℃保温后，壁厚52 mm的X80在质量分数为10%的NaCl水溶液中淬火时，表面下4 mm到中心位置的冷却速度在18.8~5.2 ℃/s之间变化，并随距表面距离的增加逐步降低；分别以5, 10, 15, 20 ℃/s的冷却速度冷却后，焊缝的冲击吸收功均低于焊态焊缝，5 ℃/s冷却速度的低温冲击功最差，10 ℃/s最优，5 ℃/s冷却速度的状态下，焊缝的硬度低于焊态焊缝，20 ℃/s冷却速度的硬度值提高明显；当冷却速度为5 ℃/s时，焊缝组织主要为准多边形铁素体；当冷却速度达到10 ℃/s时，基体晶粒尺寸有一定的降低，准多边形铁素体数量减少，晶界M/A岛体积减小，大量M/A岛以长条状和颗粒状存在于粒贝组织晶粒内部。结论 厚壁X80三通焊缝淬火时，沿厚度方向其组织和性能很不均匀，壁厚中心位置是三通焊缝质量控制的重点。 |
| 英文摘要: |
| This paper aims to investigate the important influences of thick-walled X80 pipe fitting welds overall quenching treatment on the microstructure and properties after thermoforming. In this paper, the finite element calculation of the thermal field was carried out for the quenching process of thick-walled pipe fitting heat treatment, and the microstructure and properties of the submerged arc weld at different cooling rates were studied based on the finite element calculation results. The results showed that when X80 with wall thickness of 52 mm was quenched in 10% NaCl aqueous solution after 910 ℃ insulation, the cooling rate from 4mm to the center of the surface was between 18.8-5.2 ℃/s, and gradually decreased with the increase of the distance from the surface. After being cooled at 5, 10, 15, 20 ℃/s respectively, the impact absorption energy of the weld was lower than that of the as-welded metal. The low-temperature impact energy of the weld was lower than that of the as-welded metal, and that of weld cooled at 5 ℃/s was the worst, optimal at 10 ℃/s. The hardness of the weld cooled at 5 ℃/s was lower than that of as-welded metal, and the hardness of the weld at 20 ℃/s cooling rate increased significantly. When the cooling rate was 5 ℃/s, the weld microstructure was mainly quasi-polygonal ferrite. When the cooling rate reached 10 ℃/s, the grain size of the matrix decreased to a certain extent; the number of quasi-polygonal ferrite decreased, the grain boundary M/A island volume decreased and a large number of long strips and granular M/A islands existed in bainite grains. It can be concluded that when quenching thick-walled X80 pipe fitting welds, the microstructure and properties are very uneven along the thickness direction. Wall thickness center position is the focus for quality control of tee welds. |
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