Thermo-Mechanical Simulation of Underwater Friction Stir Welding of Low Carbon Steel

Abstract

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.

Effect of Pin Shape on Thermal History of Aluminum-Steel Friction Stir Welded Joint: Computational Fluid Dynamic Modeling and Validation

“…Q and R are the activation energy and universal gas constant, respectively. In this regard, the used values for BM used in this study are presented in Table 2: In the following, the strain rate equation can be calculated by [53][54][55]:…”

Investigation of Mechanical and Microstructural Properties of Welded Specimens of AA6061-T6 Alloy with Friction Stir Welding and Parallel-Friction Stir Welding Methods

“…By changing the condition of each of the parameters, the heat and material flow distribution in the process change, which ultimately leads to a change in the mechanical quality of the joint [8][9][10][11][12][13]. The most important factors influencing the FSW process are the temperature and the material flow distribution patterns in the welding zone [14][15][16][17][18]. The heat and flow of materials created in the process derive from two factors: welding geometry and tool geometry.…”

“…In the FSW process, two different zones are formed on either side of the weld line [19][20][21][22][23]. The side where the tool pin surface rotation direction and the tool traverse direction have the same vectorial sense is called the Advancing Side (AS), and the side where the tool pin surface rotation direction and the tool traverse direction have the opposite vectorial sense is called the Retreating Side (RS) [11,16,17]. The two regions of the AS and RS have significant differences in the way of heat distribution and plastic flow patterns, which cause significant differences in mechanical and metallurgical quality in these areas [24].…”

Pin Angle Thermal Effects on Friction Stir Welding of AA5058 Aluminum Alloy: CFD Simulation and Experimental Validation

“…One of the main benefits of friction stir welding (FSW) is the possibility of joining of non-weldable alloys [1]. With the FSW processes, various metallic and non-metallic materials can be similarly or dissimilarly joined [1][2][3][4][5][6][7][8][9]. The quality of the final FSW product depends on many process parameters like rotational tool speed, tool traverse velocity, tool tilt angle, and tool plunge depth [10,11].…”