Process Evaluation and Numerical Optimization in Friction Stir Welding of Dissimilar AMCs

In recent times, any engineering material is deemed worthwhile only if it satisfies functional characteristics such as weldability, formability, machinability, etc. Aluminum-based metal matrix composites have extensive usage in modern automobile parts, aircraft components, and ship structures, mainly due to their attractive properties such as low cost, high strength-to-weight ratio, excellent corrosion and wear resistance. Friction stir welding is one of the most versatile solid-state joining processes to ensure weldability between two AMC plates. In this research work, an analysis of FSW process through parameters (e.g., composition of alumina, spindle speed, feed, etc.) in joining Alumina reinforced aluminum alloy composites Al 6061 and Al 2024 together at various proportions by analyzing properties like impact strength, hardness, flatness, and ultimate tensile strength has been done. Finally, optimization is carried out to select the best possible combination using a multi-attribute decision-making technique called the complex proportional assessment of alternatives.

Friction Stir Welding of Thick Plates of 4Y3Gd Mg Alloy: An Investigation of Microstructure and Mechanical Properties

Applications of non-ferrous light metal alloys are especially popular in the field of aerospace. Hence it is important to investigate their properties in joining processes such as welding. Solid state joining process such as friction stir welding (FSW) is quite efficient for joining non-ferrous alloys, but with thick plates, challenges increase. In this study, Mg alloy plates of thickness 11.5 mm were successfully welded via single-pass FSW. Due to the dynamic recrystallization, grain size in the stir zone was reduced to 16 µm which is ≈15 times smaller than the parent material. The optimized rotational speed and traverse speed for optimum weld integrity were found to be 710 rpm and 100 mm/min, respectively. A sound weld with 98.96% joint efficiency, having an Ultimate Tensile Strength (UTS) of 161.8 MPa and elongation of 27.83%, was accomplished. Microhardness of the nugget was increased by 14.3%.

Numerically modelled study of the plunge stage in friction stir spot welding using multi-tiered mesh partitions

Friction stir spot welding is a solid-state joining process that has attracted significant attention particularly in the field of joining of lightweight, low melting alloys. These materials include alloys of Aluminium and Magnesium amongst many others which are of great importance to the aerospace and the automobile industries. The friction stir spot welding is a complex thermo-mechanical multiphysics phenomenon and is currently a field of intense research. The motivation of the current study is to understand this complex behaviour of the joining process by simulating it in the ABAQUS CAE environment. In the friction stir spot joining technique, the plunge stage is identified as the critical stage of operation as it involves a highly transient and dynamic zone for material and temperature flows. The plunge stage was studied in detail using the finite element based model. The plasticity of the material was simulated by the Johnson-Cook material model while the frictional heat generation was captured by applying a penalty-based frictional contact between the rotating tool and the workpiece contact surfaces. Considering the reasonable assumptions made, the results obtained by the numerical simulation model were found to agree with the past experimental and numerically modelled studies.

Numerical and Empirical Studies on Friction Stir Welding of Yellow Brass 405-20

Friction stir welding (FSW) is an eco-friendly and solid-state joining technology. Due to this reason, industries are keenly adopting this joining process in their various applications e.g., automobile, aerospace, marine, etc. Several materials have already been welded by FSW including aluminum, copper, steel, alloys of these materials, plastics, composites, and list are still going on. Few researchers have welded the brass using FSW. In this research, yellow brass 405-20 is welded with FSW for the very first time. Thermal distribution during FSW of brass was recorded via both simulations and experiments. Moreover, ultimate tensile strength was also measured numerically with its validation from its empirical counterpart. Finally, hardness was measured numerically in the form of compressive strength of welded brass, and it was also validated experimentally. Three aspects of validated simulations were never studied for brass 405-20 before and finally a good and close match was found between results from both simulations and experiments.

Nature of CoCrFeMnNi/Fe and CoCrFeMnNi/Al Solid/Solid Interface

To shed light into the application potential of high-entropy alloys as “interlayer” materials for Al-steel solid-state joining, we investigated the nature of the CoCrFeMnNi/Fe and CoCrFeMnNi/Al solid/solid interfaces, focusing on the bonding behavior and phase components. Good metallurgical bonding without the formation of hard and brittle IMC can be achieved for CoCrFeMnNi/Fe solid/solid interface. In contrast to the formation of Al5Fe2 phase at the Fe/Al interface, Al13Fe4-type IMC, in which the Fe site is co-occupied equally by Co, Cr, Fe, Mn and Ni, dominates the CoCrFeMnNi/Al interface. Although the formation of IMC at the CoCrFeMnNi/Al interface is not avoidable, the thickness and hardness of the Al13(CoCrFeMnNi)4 phase formed at the CoCrFeMnNi/Al interface are significantly lower than the Al5Fe2 phase formed at the Fe/Al interface. The activation energies for the interdiffusion of Fe/Al and CoCrFeMnNi/Al static diffusion couple are 341.6 kJ/mol and 329.5 kJ/mol, respectively. Despite this similarity, under identical static annealing condition, the interdiffusion coefficient of the CoCrFeMnNi/Al diffusion couple is significantly lower than that of the Fe/Al diffusion couple. This is thus mainly a result of the reduced atomic mobility/diffusivity caused by the compositional complexity in CoCrFeMnNi high-entropy alloy.

EFFECT OF PRE-HEATING ON THE MECHANICAL PROPERTIES OF FRICTION STIR WELDING FOR 6061 ALUMINUM ALLOY

Friction stir welding (FSW) process is a solid-state joining invented via the Welding Institute in 1991 at a great rate emerging as an application by fusion welding for joining different alloys. The wrought aluminum alloy 6061 is heat treatable and possesses a high corrosion resistance. This alloy has been used in a wide range of applications, like arenas gymnasiums and trains bodies. Aluminum alloy 6061 cannot be easily welded by the conventional fusion welding process because of the cracks that make the mechanical of welding joint very weak. In FSW, many parameters effect on its welding process. In the present research, the pre-heating effect on the aluminum 6061 sheet at 100°C and 150°C was studied. This heat has to be given for obtaining a defect-free as well as quality joint. Result manifested that the welding without pre-heating the parent metal at a (1120 r.p.m) rotational speed and a (30 mm/min) welding speed gave the best result of the ultimate tensile strength (236 N/mm2).

High-Speed Friction Welding as an Innovative Technology for Joining Solenoid Valve Elements Made of Steel Grades 11SMnPb37 and 11SMn37

High-speed friction welding (HSFW) is a solid-state joining process involving the use of friction heat emitted during the technological process. The application of the HSFW technology enables the fast and repeatable making of joints characterised by favourable properties. The article presents tests concernin the development of the HSFW-based technology enabling the joining of solenoid valve elements made of two grades of free-cutting steel, i.e. 11SMnPb37 and 11SMn37. The article also discusses the course of technological tests, the making of a test rig, the determination of ranges of technological parameters and selected test results concerning welded joints.

The Effect of Tool Rotation Speed on Hardness, Tensile Strength, and Microstructure of Dissimilar Friction Stir Welding of Dissimilar AA5083 and AA6061-T6 Alloys

The welding between two different grades of aluminum alloy, specifically AA5083 and AA6061-T6, is very difficult to obtain optimal results when using conventional welding methods such as TIG/MIG welding. Therefore, a solid-state joining technique is highly recommended to overcome these problems, one of which is friction stir welding (FSW). The effect of rotation speed on microstructure, microhardness, and tensile properties of dissimilar Friction Stir welded AA5083 and AA6061-T6 aluminum alloys were investigated. Three different rotation speeds (910, 1500, and 2280 rpm) were used to weld the dissimilar alloys. The metallographic analysis of joints showed the presence of various zones such as BM (base material), HAZ (heat affected zone), TMAZ (thermo-mechanically affected zone), and NZ (nugget zone) were observed and analyzed by mean of optical and scanning electron microscope. The results showed that increasing the rotation speed from 900 to 2280 rpm made grain coarsening in NZ and the mass distribution of the material is more evenly distributed, as well as increased hardness and tensile strength of the joint. The highest values in microhardness in NZ and tensile strength at the join were founded at the speed of 2280 rpm and 1500 rpm which was similar to 2280 rpm, respectively.

ANALYTICAL AND NUMERICAL THERMAL ANALYSIS ON FRICTION STIR WELDING USING POLYGONAL TOOL PIN

Frictional heat generation in the tool/matrix interface followed by the stirring of material along the weld line causes plasticized solid state joining in friction stir welding. In this paper, the existing torque based thermo-mechanical model for the tools with cylindrical pins is remodified for the polygonal tool pin profile by introducing novel multiplication factors with respect to the number of sides in the tool pin geometry. The variation in the effective heat supply with respect to the chosen pin geometry was analyzed. A comparative analysis of the proposed analytical model with the existing model was also carried out to understand the accuracy of the proposed model. Furthermore, a transient thermal numerical modelling was carried out in the view of understanding the change in process peak temperature in the stir zone and change in temperature gradient along the heat affected zone with respect to the change in pin geometry for the opted set of process input parameters. An analytically estimated heat-input-based numerical model was adopted in the present study. It was observed that the process peak temperature was directly proportional to the number of sides in the tool pin. ABSTRAK: Penjanaan haba geseran antara muka pada alat/matrik diikuti dengan pengacauan material sepanjang garis kimpalan menyebabkan keadaan plastik pepejal melekat bersama geseran kimpalan pengacau. Kajian ini berkaitan tork sedia ada berdasarkan model mekanikal-terma bagi alat pin silinder yang terubah suai bagi profil pin alat poligon dengan memperkenalkan faktor gandaan berdasarkan bilangan sisi geometri alat pin. Perubahan pada bekalan haba efektif berdasarkan geometri pin pilihan telah dikaji. Analisis bandingan pada model analitik yang dicadang bersama model sedia ada, telah dilakukan bagi memahami ketepatan model cadangan. Tambahan, model transien numerikal terma telah dibuat bagi memahami proses perubahan suhu puncak ketika zon pengacauan dan perubahan gradien suhu sepanjang zon terkena haba perubahan geometri pin pada set proses parameter input terpilih. Kajian ini mengaplikasi model numerik berdasarkan input anggaran haba secara analitik. Dapatan kajian menunjukkan suhu puncak proses adalah berkadar langsung dengan bilangan sisi pin alat.