摘要
针对AP1000核电主管道在热处理过程中产生的温度分布不均、薄壁处奥氏体晶粒粗大以及应力变形等问题提出了一种均匀化加热热处理的新工艺,在管道薄壁处覆盖网格状绝热材料,依据厚薄部位的壁厚关系调控薄壁部位受热面积,从而使管道整体升温均匀。采用数值模拟的方法验证该工艺的有效性。利用ANSYS软件对AP1000核电主管道在新工艺下的热处理加热阶段进行了热-力耦合数值模拟,将采用新工艺和传统工艺的温度场和应力场模拟结果进行了对比。结果表明,新工艺能显著降低工件厚薄部位中心的温差,最大温差从110℃下降到20℃,同时局部热应力较传统工艺大幅度下降,最大下降80%。因此,采用新工艺能够有效实现工件升温的均匀性,避免局部晶粒粗大,同时降低工件热应力。
Aiming at the problems of uneven temperature distribution, coarse austenite grain at thin wall and stress deformation, in heat treatment of AP1000 nuclear power primary piping, a new uniform heating heat treatment process was proposed. The thin wall of pipeline was covered with reticulated insulation material, and the heating area of thin wall was regulated according to the relation of wall thickness of the thick and thin part, so that the whole pipeline is heated up evenly.The effectiveness of the process was verified by numerical simulation. The thermal-mechanical coupling numerical simulation of the heat treatment heating stage of the AP1000 nuclear power pipeline under the new process was carried out by using ANSYS software. The simulation results of the temperature field and the stress field using the new process and the traditional process were compared. The results show that, the new process can significantly reduce the temperature difference between the thick and thin parts of the workpiece, the maximum temperature difference decreases from 110 ℃ to 20 ℃, and the local thermal stress decreases by a large margin, and the maximum temperature difference decreases by 80% compared with that of the traditional process. Therefore, the new process can effectively realize the homogeneity during workpiece heating, avoid local coarse grain, and reduce the thermal stress during workpiece at the same time.
引文
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