Modeling of thermal cycles and microstructural analysis of pipeline steels processed by friction stir processing
Modeling of thermal cycles and microstructural analysis of pipeline steels processed by friction stir processing
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DOI：
10.1007/s00170-018-2408-9
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发表时间：
2018-10-01
影响因子：
3.4
通讯作者：
Ramirez, A. J.
中科院分区：
文献类型：
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作者：
Avila, J. A.;Giorjao, R. A. R.;Ramirez, A. J.
在搅拌摩擦焊接或加工(FSP)过程中，温度和变形对最终组织和力学性能有影响。研究焊接前后的显微组织可能有助于解释力学和耐腐蚀性；然而，焊接过程中的组织演变仍不清楚。在本研究中，建立了管线钢板的FSP模型。在FSP过程中，将热电偶插入不同的位置，并收集温度循环。收集的数据用于完成基于计算流体力学(CFD)的数值模型。CFD模型将材料视为流体，模拟了FSP内的材料流动和换热。模拟峰值温度与实验结果之间的标准误差小于1%。该模型允许将峰值温度和冷却速度与FSP后获得的微观组织相关联。数值结果表明，搅拌区的峰值温度和停留时间足够高，足以导致颗粒粗化。这一观察结果在先前的奥氏体晶粒度测量中得到了证实。
During friction stir welding or processing (FSP), temperature and deformation have influence on the final microstructure and mechanical properties. Studying microstructures before and after welding might help interpreting mechanical and corrosion resistance; however, microstructural evolution during the process remains unknown. In this study, a FSP model of pipeline steel plates was developed. Thermocouples were inserted in different positions and temperature cycles were collected during FSP. The collected data was used to complete the numerical model based on computational fluid dynamics (CFD). The CFD model simulated the material flow and heat transfer in FSP considering the material as a fluid. The standard error between the peak temperatures of the simulation and experimental results was below 1%. The model allowed correlating peak temperatures and cooling rates to the obtained microstructures after FSP. Numerical results showed that peak temperatures and dwell times in the stir zone were high enough to cause grain coarsening. This observation was demonstrated upon prior-austenite grain size measurements.