Papers by Keyword: Friction Stir Welding (FSW)

Abstract: Jointing with rotary active element gains field through technological facilities offered nowadays. Own research have developed a model for studying the thermal fields and the plastic deformations of jointing composite materials Al/20%SiC combined by friction stir welding (FSW). In this article we will present the three-dimensional distribution of investigated fields, correlated with input parameters in the process. The process is performed with solid state components. The numerical results indicate that the maximum temperature in the FSW process increases with increasing speed of rotational tools. For high speed welding joint, should be increased, at the same time, the rotational speed to avoid welding defects.

Abstract: Friction stir welding (FSW) is a new and promising welding process which can produce low cost and high quality joints of heat-treatable aluminum alloys. This is because it does not require the consumable filler materials and can eliminate some welding defects such as crack and porosity. The main objective of the present work was to evaluate the processing parameter of friction stir welding (FSW) process for 6061-T6 alloy and to determine the properties of the obtained joints. Experiments have been conducted by varying the friction stir welding processing parameter ; tool rotational speed, in rpm (410, 865, 1140) and feed rate, in mm/min (22, 32, 45). The shoulder diameter of the tool for FSW was 18 mm. Microstructure, microhardness and tensile properties were investigated in this studied. The results showed that there was a variation of grain size in each weld zone which depends on the material and process parameters of FSW in the joint itself. The coarsest grain size was observed in the heat affect zone (HAZ), followed by the Thermo Mechanically Affected Zone (TMAZ) and the nugget zone. The highest hardness was reported on the nugget zone and maximum tensile strength was obtained on the sample with processing parameter 865 rpm rotational speed.

Abstract: The Texture Developed in High-Temperature β Phase during Friction Stir Welding of Ti-6Al-4V Was Studied. It Was Demonstrated that 0002 and 1120 Pole Figures Calculated from α Phase May Be Employed for Interpretation of Material Flow in the β Phase. Together with Orientation Measurements in Retained β Phase, this Approach Was Shown to Be a Very Simple and Effective for the Texture Analysis. The β Texture Was Found to Be a Mixture of {hkl}<111>-Fiber Texture and D₂(112)[111](Simple-Shear Texture Component.

Abstract: Friction stir welding is a technique useful for joining aluminum alloys that are difficult to weld. In recent years, however the focuses has been on welding dissimilar aluminum alloys, and analyze their mechanical properties and micro-structural characteristics. In the present study, the less investigated welding of cast aluminum alloys is considered. Cast aluminum alloys, A356 and A413, commonly used in automotive and aerospace industries, were friction-stir welded and their mechanical properties and micro-structural characteristics were analyzed. On testing their welded region, no welding defects were observed. The welded region exhibited a maximum tensile strength of 90 N/mm² and Vickers micro-hardness of 56.8. The micro-structural observations at the nugget region revealed a refined grain structure.

Abstract: The friction stir welded superplastic forming of AA6061-T6 sheet has been numerically analyzed based on the experimental and finite element software. A selected range of tool rotating speeds of 500, 1000 and 2000 rpm was used for friction stir welding. At constant temperature of 550^O C and constant pressure of 0.4 Mpa, superplastic forming experiments was performed using free forming die for the friction stir welded sheets. A detailed 3D element type study has been performed in the finite element analysis. The proposed finite element model has been validated in comparison with experimental data. The results are found to have reasonably good agreement between simulations and experiment. The effect of constant pressure, coefficient of friction, strainrate and strain-rate sensitivity has been studied using the proposed finite element model.

Abstract: A 3D thermal pseudo mechanical model formulated in an Eulerian frame considering a quassisteady approach to Friction Stir welding modeling of AA6061 Aluminium alloy is proposed and implemented using nonlinear finite element code in Comsol Multiphysics v 4.1. The effect of different operating parameters on the temperature distribution was analyzed. The material flow is found to be enhanced with the increase in traverse speed and angular velocity of the pin with a pronounced swirl on the advancing side. The distribution of equivalent plastic strain and dynamic viscosity was found to correlate with the distribution of the microstructure zones in the weld.

Abstract: The butt joints of semi solid 356 were produced in as cast conditions by friction stir welding process (FSW). This experiment studied in pre/post heat treatment (T6) using the welding speed 160 mm / min with tilt angle tool at 3 degree and straight cylindrical tool pin. The factors of welding were rotating speed rates at 1320, 1750 rpm and heat treatment conditions. They were divided into (1) As welded (AW) joints, (2) T6 Weld (TW) joints, (3) Weld T6 (WT) joints, (4) T6 Weld T6 (TWT) joints, (5) Solution treated Weld Artificially aged (SWA) joints and (6) Weld Artificially aged (WA) joints. Rotating speed and heat treatment (T6) condition were an important factor to micro, macro structure of metal and mechanical properties of the weld. Increasing rotating speed and different heat treatment condition impacted onto tensile strength due to the defects on joints. Therefore the optimum welding parameter on joint was a rotating speed 1320 rpm, the welding speed 160 mm/min, heat treatment condition of Weld T6 (WT) which obtained the highest tensile strength 228.92 MPa, as well as, highest hardness of 98.1 HV

Abstract: This research characterizes the changes in microstructure that occur in friction stir welded extrusions of a novel 7042 aluminum alloy. Due to the presence of scandium the base material preserved the deformation microstructure with elongated grains and fairly high dislocation density. The temperature increase with simultaneous severe plastic deformation occurring during friction stir welding induced significant changes in the microstructure within the weld and its vicinity. The weld center (stir zone) was composed of fine equiaxed grains with residual dislocations and a modest density of small precipitates compared to the neighbouring thermomechanically and heat affected zones where the density of small precipitates was much higher.

Abstract: Residual stress distribution plays a very important role in welded structures, the aim of present work is to find out the effect of different welding methods on the residual stress distribution by means of neutron diffraction measurements and FE models simulation. 4 mm thick DH-36 steel plates were butt welded by MIG welding process and 5 mm thick AA 2024 aluminium alloy plates were butt welded by friction stir welding process. Results show that residual stresses of MIG welding process are higher than those of friction stir welding process. The peak residual stress of MIG weld is close to the room temperature uniaxial yield strength of DH-36 while the peak residual stress of friction stir weld is just about 50% of the room temperature uniaxial yield strength of AA2024. The size effect of MIG welded and effect of welding speeds of friction stir welded on the residual stress distribution have also been studied in the paper.

Abstract: A finite element model of radar cooling board friction stir welding process was built in ANSYS software based on an instantaneous relative linear velocity heat source model. Temporal and spatial temperature distribution disciplinarians were analyzed; results show that the peak temperature is lower than the base material melting point, as a result there is no material melt during the welding process. Temperatures change disciplinarily with the progress of welding process at each point.