Local heat generation and material flow in friction stir welding of mild steel assemblies

Abstract

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Modelling of friction stir welding of DH36 steel

“…The tool and the plate were considered in the fully sticking condition. To make the model more robust, a thermal convection coefficient with high values (1000-2000 W/m 2 .K) was applied on the bottom surface of the plate instead of representing the backing plate and the anvil [4].…”

“…In the current model the radiation equation was neglected as it will add more complexity to the case. As a first approximation the radiation effect was accommodated by increasing the value of heat convection coefficient around the tool [4].…”

“…Similar to this finding, Fehrenbacher et al [28] developed a measurement system for FSW of aluminium alloys and measured the temperature of the interface between the tool and the plate experimentally using thermocouples and found that the maximum temperature was at the shoulder interface in the advancing-trailing side closer to the advancing side of the welds. Micallef et al [4] by using CFD modelling and experimental validation, found that the maximum temperature occurs on the advancing side and towards the rear of the shoulder's surface while the minimum temperature occurs in the pin region at the leading edge of the tool. Lower plastic deformation due to the lower viscosity at the front of the tool surface has been given as a reason for this minimum temperature.…”

“…They established a 3D thermo-fluid model to simulate the material flow, strain-rate and temperature distribution. Micallef et al [4] carried out work on CFD modelling and calculating the heat flux of FSW DH36 6-mm plates by assuming full sticking conditions at the tool shoulder/workpiece and that the heat is generated by plastic deformation and shearing. The effects of different welding conditions including slow, intermediate and fast rotational traverse FSW speeds on stir zone (SZ) size and heat generated was studied.…”

“…Few people have succeeded in predicting the size, shape and position of the SZ using numerical analysis. Micallef et al [4] tried to predict the SZ by determining the velocity of stirring which can represent the transition between stir and no stir. However, because there is no certain value of the stirring velocity, this method can contain many errors.…”