The effects of friction stir welding on the mechanical properties and microstructure of 7000 series aluminium tailor-welded blanks (original) (raw)
Related papers
2006
The effect of processing parameters on mechanical and microstructural properties of aluminium alloy 6082-T6 Friction stir-welded (FSW) joints were investigated in the present study. Different welded specimens were produced by employing variable rotating speeds and welding speeds. Tensile strength of the produced joints was tested at room temperature and the correlation with process parameter was assessed. Microstructures of various zones of FSW welds are presented and analyzed by means of optical microscopy and microhardness measurements. Several studies have been conducted to investigate the properties and microstructural changes in Friction Stir Welds in the aluminium alloy 6082-T6 in function of varying process parameters. The experimental results indicated that the process parameters have a significant effect on weld macrostructure and mechanical properties of joints.
Friction stir welding (FSW) process is a promising solid-state joining process with the potential to join low-melting point material, particularly, aluminium alloy. The most attractive reason for joining aluminium alloy with this process is the avoidance of the solidification defects formed by conventional fusion welding processes. In this research article, an attempt has been made to develop an empirical relationship between FSW variables and Micro Hardness. A factorial design was used by considering three factor and eight trials, which enables to quantify the direct and interactive effect of three numeric factors, that is, tool rotational speed, welding speed, and shoulder diameter on the Micro Hardness. The developed relationship is useful for prediction of Micro Hardness in friction stir welded AA6061 aluminium alloy joints at 95% confidence level. It will also be helpful for selection of process variable to obtain the desired strength of the joint. Furthermore, the optimized capabilities in design-expert software were used to numerically optimize the input parameters. I. INTRODUCTION In many industrial applications steel is readily replaced by non-ferrous alloy, in most cases aluminium alloys. Some of these materials combine mechanical strength comparable with structural steel and low weight, allowing for a significant reduction of weight. But the joining of aluminium alloys can sometimes cause a serious problem by the conventional welding process. The difficulty is often attributed to the solidification process and structure including loss of alloying elements and presence of segregation and porosities. Friction stir welding (FSW) offers an alternative through solid-state bonding, which eliminates all these problems of solidification associated with the conventional fusion welding processes. The dependence on friction and plastic work for the heat source precludes significant melting in the work piece, avoiding many of the difficulties arising from a change in states, such as changes in gas solubility and volumetric changes, which often plague fusion welding processes. Further, the reduced welding temperature makes possible dramatically lower distortion and residual stresses, enabling improved fatigue performance and new construction techniques and making possible the welding of very thin and thick materials. FSW has also been shown to eliminate or dramatically reduce the formation of hazardous fumes and reduces energy consumption during welding, reducing the environmental impact of the joining process. Further, FSW can be used in any orientation without regard to the influence of gravitational effects on the process. These distinctions from conventional arc welding processes make FSW a valuable manufacturing process with undeniable technical, economic, and environmental benefits. The process and the terminology are schematically explained in Fig: 1.1. The welding process parameters such as tool rotational speed, welding speed, and pin diameter play a major role in deciding the weld quality. In general, the solid-state nature of the FSW process, combined with its unusual tool and asymmetric nature, results in a highly characteristic microstructure. The microstructure can be broken up into the following zones as explained in Fig: 1.2.
Materials, 2021
The present study investigates the effect of two parameters of process type and tool offset on tensile, microhardness, and microstructure properties of AA6061-T6 aluminum alloy joints. Three methods of Friction Stir Welding (FSW), Advancing Parallel-Friction Stir Welding (AP-FSW), and Retreating Parallel-Friction Stir Welding (RP-FSW) were used. In addition, four modes of 0.5, 1, 1.5, and 2 mm of tool offset were used in two welding passes in AP-FSW and RP-FSW processes. Based on the results, it was found that the mechanical properties of welded specimens with AP-FSW and RP-FSW techniques experience significant increments compared to FSW specimens. The best mechanical and microstructural properties were observed in the samples welded by RP-FSW, AP-FSW, and FSW methods, respectively. Welded specimens with the RP-FSW technique had better mechanical properties than other specimens due to the concentration of material flow in the weld nugget and proper microstructure refinement. In both AP-FSW and RP-FSW processes, by increasing the tool offset to 1.5 mm, joint efficiency increased significantly. The highest weld strength was found for welded specimens by RP-FSW and AP-FSW processes with a 1.5 mm tool offset. The peak sample of the RP-FSW process (1.5 mm offset) had the closest mechanical properties to the base metal, in which the Yield Stress (YS), ultimate tensile strength (UTS), and elongation percentage (E%) were 76.4%, 86.5%, and 70% of base metal, respectively. In the welding area, RP-FSW specimens had smaller average grain size and higher hardness values than AP-FSW specimens.
Experimental, Mechanical Characterizations of Friction Welding of Steel and Aluminium Joints
Journal of Advances in Manufacturing Engineering, 2020
Rotary friction welding (RFW) is a solid-state joining process which works by rotating one workpiece relative to another while under a compressive axial force, which produces coalescence of materials workpieces. It is considered most viable alternative to overcome the difficulties faced in conventional joining techniques. As it is a solid state welding process, the process does not form molten pool thereby eliminating the solidification errors. It offers many advantages for some manufacturing sectors for a wide range of applications. In this research, we investigated the mechanical and metallurgical characteristics of RFW welded joints for homogenous and heterogeneous assemblies. We have studied A60 steels and 2017A series aluminum alloys. The obtained welds are similar in appearance in that they have several Microstructural distinct zones. So, the results show that by increasing the rotating speed employing 1000 and 1600 rpm, the mechanical properties during the RFW process is lightly improved, favored by the increase in heat flow. In the same specimen, the micro hardness distribution is generally viewed lightly changed between center line throw weld of welded tube and close to their boundary line. This is due to the no-uniform of temperature distribution in cross section. Thus, plastic deformation of heated portion of the metal plays an important role in friction welding process and their quality. Microstructural analysis reveals that grain growth in the joint WCZ and in heat affected zone HAZ because of the no-uniform of thermal flux distribution in both directions (transvers and longitudinal of tube). Finally using RFW, the fabricators allow to perform and maintenance the mechanical components with low cost and which it conserves their welding quality compared to the classical fusion welding.
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2020
A tailor welded blank (TWB) includes two or more blanks joined together in order to make a single blank. Different welding methods are used to join blanks with different characteristics and form TWBs. In this study, a comparison is made among the effects of three different welding methods namely CO2 laser welding, friction stir welding (FSW), and friction stir vibration welding (FSVW) on mechanical and formability properties of developed TWBs. AA6061 alloy sheets with different thicknesses (1.2 and 0.8 mm) are joined to get TWBs. The forming limit diagram (FLD) and limiting dome height (LDH) are applied to assess the formability. The Taguchi method is applied to find the optimum values of welding parameters. It is concluded that TWBs made by FSVW have higher mechanical properties and formability compared to TWBs made by FSW and CO2 laser welding. The results also indicate that FLD for TWBs made by FSW is higher than FLD for TWBs made by CO2 laser welding and FLD0, for TWBs made by F...
Impact of TIG Welding Parameters on the Mechanical Properties of 6061-T6 Aluminum Alloy Joints
Advances in Science and Technology Research Journal
The most common gas-shielded arc welding method is tungsten inert gas welding, which uses shielding gas to isolate the welded area. Such technique is mostly used in the industrial domain, including steel framework fabrication and installation, plumbing systems, and other building jobs. The welding method and the implementation of a suitable welding joint based on some factors that contribute to the fusion process were studied in the present research. The research investigated the specifications and efficiency of the area to be welded in terms of the thermal effect on the welding joint shape and some significant mechanical property-related factors which that were determined during the welding process. In this paper, aluminum alloy sheets, AA 6061-T6, with a thickness of 3 mm, were used with a 60mm width and 80mm length. These sheets were prepared to be welded using welding currents of 90A, 95A, and 100A, welding speeds of 60mm/min, 80 mm/min, and100 mm/min, and gas flow rates of 8 l/ min, 9 l/min, and 10 l/min. The experiments were designed at three distinct levels. These levels were selected to create the L9 orthogonal array. Regression analysis, signal-to-noise ratio evaluation, and analysis of variance were carried out. The created model has enhanced accuracy by predicting the reinforced hardness found in the weld specimens, according to the regression study, which showed R2= 90.09%. In addition, it was discovered that the ideal welding parameters for a welded specimen were 100 A for welding current, 80 mm/min for welding speed, and 9 l/min for gas flow. The present research examined the shape of the thermal distribution of welded parts using the engineering computer program ANSYS. The experimental results clarified the proposed approach, as they showed that the welding current is the most influential factor in the hardness of the weld using the fusion process of 90.95%, followed by the welding speed of 7.48%, while the gas flow rate of 1.52% has the least effect. The authors recommend using qualified welders to ensure optimal performance. It is anticipated that these findings will serve as a foundation for analysis to optimize welding processes and reduce welding defects.
An experimental investigation has been carried out on microstructure and tensile properties of weld b of aluminium alloy. Two different welding processes have been considered: a conventional tungsten inert gas (TIG) process and an innovative solid state welding process known as friction stir welding (FSW) process. In this study, it has been found that heat affected zone of FSW is narrower than TIG welding and mechanical properties like tensile strength etc. are within the comfort zone and are better than TIG welding method. Microstructure results also favour FSW. TIG welding process produces the sound joints but the newly developed method friction stir welding process gives better joints than TIG welding process. The effect of two welding processes on mechanical and metallurgical properties is studied in this research work. Mechanical properties of the welded joints were evaluated and it was found that friction stir welded joints have superior mechanical properties as compared to TIG welded joints. From the micro structure analysis, it was observed that fine and equiaxed grains were observed in the friction stir welded joints and coarse grains were observed in TIG welded joints.
In present world the requirement of material arises which have high strength to weight ratio. The material like Al , Mg have such properties but the joining of this material is nearly impossible with traditional fusion welding processes. TWI in 1991 patented a technique called friction Stir Welding (FSW), which can weld materials by melting the material by 70-80% of its melting temperature. By using this technique material which are hard welded can be welded. Butt, Lap T, Cylindrical, Hollow joints can be welded. In this review a study is done on mechanical properties affected by process parameters of friction stir welding & to which extend. The material welded by FSW gives better mechanical properties than material welded by tradition fusion welding processes. Application & Future Scope are discussed in this study.
2011
The (FSW) of commercial aluminum were studied. The Vickers microstructure of the tested spacemen’s ranged from (33-48) VHN. The mechanical properties were investigated and the result shows that they are dependents on the weld test parameters such as spacemen thickness weld speed and weld pressure. The microstructure, including grain and sup grain structure, of has metals were compared with the weld zone and heat effected zone using transition electron microscopy. The microstructure of weld zone was characterized by dynamic recrastallization producing fine grain structure. However ,the heat affected zone exhibited an inhalation of the dislocations due to the increase the welding pressure at the welded joints which lead to formation of porous ,cavities and uneven deformed layers.