Memon Shabbir, Tomków Jacek, Derazkola Hesamoddin Aghajani
Department of Mechanical Engineering, Wichita State University, Wichita, KS 67260-133, USA.
Institute of Machines and Materials Technology, Faculty of Mechanical Engineering and Ship Technology, Gdańsk University of Technology, Gabriela Narutowicza Street 11/12, 80-233 Gdańsk, Poland.
Materials (Basel). 2021 Aug 30;14(17):4953. doi: 10.3390/ma14174953.
This article investigates the flow of materials and weld formation during underwater friction stir welding (UFSW) of low carbon steel. A thermo-mechanical model is used to understand the relation between frictional heat phenomena during the welding and weld properties. To better understand the effects of the water environment, the simulation and experimental results were compared with the sample prepared by the traditional friction stir welding (FSW) method. Simulation results from surface heat diffusion indicate a smaller preheated area in front of the FSW tool declined the total generated heat in the UFSWed case compared to the FSWed sample. The simulation results revealed that the strain rate of steel in the stir zone (SZ) of the FSWed joint is higher than in the UFSWed case. The microstructure of the welded sample shows that SZ's microstructure at the UFSWed case is more refined than the FSWed case due to the higher cooling rate of the water environment. Due to obtained results, the maximum temperatures of FSWed and UFSWed cases were 1228 °C and 1008 °C. Meanwhile, the simulation results show 1200 °C and 970 °C for conventional and underwater FSW samples, respectively. The maximum material velocity in SZ predicted 0.40 m/s and 0.32 m/s for FSW and underwater FSWed samples. The better condition in the UFSW case caused the ultimate tensile strength of welded sample to increase ~20% compared to the FSW joint.
本文研究了低碳钢水下搅拌摩擦焊（UFSW）过程中的材料流动和焊缝形成。采用热-机械模型来理解焊接过程中摩擦热现象与焊缝性能之间的关系。为了更好地理解水环境的影响，将模拟和实验结果与采用传统搅拌摩擦焊（FSW）方法制备的样品进行了比较。表面热扩散的模拟结果表明，与FSW焊接的样品相比，FSW工具前方预热面积较小，使得UFSW焊接情况下产生的总热量减少。模拟结果显示，FSW焊接接头搅拌区（SZ）中钢的应变速率高于UFSW焊接情况。焊接样品的微观结构表明，由于水环境的冷却速率较高，UFSW焊接情况下SZ的微观结构比FSW焊接情况更细化。根据所得结果，FSW和UFSW焊接情况下的最高温度分别为1228℃和1008℃。同时，模拟结果显示传统FSW和水下FSW样品的最高温度分别为1200℃和970℃。对于FSW和水下FSW焊接样品，SZ中预测的最大材料速度分别为0.40m/s和0.32m/s。UFSW情况下的较好条件使得焊接样品的抗拉强度相比FSW接头提高了约20%。
