Material flow and mechanical properties of friction stir welded Al-Mg-Si alloy: Role of concentric circles shoulder with non-circular pins

2021 ◽  
pp. 095440622198939
Author(s):  
Krishna Kishore Mugada ◽  
Kumar Adepu
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Process Conditions ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Average Hardness ◽  
Concentric Circles

Understanding the material flow in friction stir welding (FSW) is one of the challenging aspects for producing defect free and quality welds. The material flow is majorly governed by the tool shoulder/pin geometries and process conditions. In the present study, concentric circles shoulder shape with various polygonal pin designs are selected, and their influence on material flow and mechanical properties in Al 6082 friction stir welds is addressed. Material flow is studied by inserting the markers before welding and subsequent analysis of deformed marker material by radiography and macrostructure after welding. The outcome shows the welds with square pin design facilitated a constant stable force, and hexagonal pin design facilitated a decreasing behavior of force with reference to welding length/time. The heat input is increasing from triangular pin to hexagonal pin and is maximum for welds with hexagonal pins (973 kJ/mm). Further, welds with hexagonal pins (TCC)HEX tool facilitated higher mechanical properties of strength (187 MPa) and average hardness (79 HV) at the stir zone.

scholarly journals Material Flow Visualization of Dissimilar Friction STIR Welding Process Using Nano-Computed Tomography

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Xun Liu ◽  
Sheng Zhao ◽  
Kai Chen ◽  
Jun Ni
Keyword(s):  
Computed Tomography ◽  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Volume Fraction ◽  
Weld Zone ◽  
Process Conditions ◽  
Rotating Speed ◽  
Friction Stir ◽  
Small Tool

In this study, the friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel is analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-computed tomography (nano-CT) is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset, and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.

Material Flow Visualization of Dissimilar Friction Stir Welding Process Using Nano-CT

2018 ◽  
Author(s):  
Xun Liu ◽  
Sheng Zhao ◽  
Jun Ni
Keyword(s):  
Friction Stir Welding ◽  
Heat Input ◽  
Material Flow ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Weld Zone ◽  
Process Conditions ◽  
Rotating Speed ◽  
Friction Stir ◽  
Small Tool

In this study, Friction stir welding (FSW) of aluminum alloy 6061-T6511 to TRIP 780 steel are analyzed under various process conditions. Two FSW tools with different sizes are used. To understand the underlying joining mechanisms and material flow behavior, nano-CT is applied for a 3D visualization of material distribution in the weld. With insufficient heat input, steel fragments are generally scattered in the weld zone in large pieces. This is observed in a combined condition of big tool, small tool offset and low rotating speed or a small tool with low rotating speed. Higher heat input improves the material flowability and generates a continuous strip of steel. The remaining steel fragments are much finer. When the volume fraction of steel involved in the stirring nugget is small, this steel strip can be in a flat shape near the bottom, which generally corresponds to a better joint quality and the joint would fracture in the base aluminum side. Otherwise, a hook structure is formed and reduces the joint strength. The joint would fail with a combined brittle behavior on the steel hook and a ductile behavior in the surrounding aluminum matrix.

A Study on the Thermal Deformation of Fillet Joint Friction Stir Welding

2020 ◽  
Author(s):  
Sungwook Kang ◽  
Jaewoong Kim ◽  
Donghyun Kim ◽  
Kwangjin Lee ◽  
Yoonchul Jung
Keyword(s):  
Friction Stir Welding ◽  
Heat Source ◽  
Welding Process ◽  
Frictional Heat ◽  
Process Conditions ◽  
Joint Friction ◽  
Friction Stir ◽  
Tool Shoulder ◽  
Tool Shape ◽  
Fillet Joint

Abstract In this study, experiments and simulations were performed for fillet joint friction stir welding according to tool shape and welding conditions. Conventional butt friction stir welding has good weldability because heat is generated by friction with the bottom of the tool shoulder. However, in the case of fillet friction stir welding, the frictional heat is not sufficiently generated at the bottom of the tool shoulder due to the shape of the tool and the shape of the joint. Therefore, it is important to sufficiently generate frictional heat by slowing the welding speed as compared to butt welding. In this study, experiments and simulations were carried out on an aluminum battery housing made by friction stir welding an extruded material with a fillet joint. The temperature of the structure was measured using thermocouple during welding, and the heat source was calculated through correlation analysis. Thermal elasto-plastic analysis of the structure was carried out using the calculated heat source and geometric boundary conditions. It is confirmed that the experimental results and the simulation results are well matched. Based on the results of the study, the deformation of the structure can be calculated through simulation even if the tool shape and welding process conditions change.

Microstructure and Mechanical Properties of Friction Stir Welded Annealed Pure Copper Joints

2013 ◽  
Vol 787 ◽  
pp. 346-351
Author(s):  
Salar Salahi ◽  
Vahid Rezazadeh ◽  
Atabak Iranizad ◽  
Ali Hosseinzadeh ◽  
Amir Safari
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Welding Speed ◽  
Heat Input ◽  
Applied Load ◽  
Rotation Speed ◽  
Pure Copper ◽  
Friction Stir ◽  
Tool Rotation Speed ◽  
Tool Rotation

As a novel technique for joining materials, friction stir welding (FSW) has significant advantages over the conventional welding methods and is widely applied for joining different materials including aluminum, magnesium and copper alloys. In this research, the mechanical and microstructural characteristics of friction stir welded annealed pure copper joints were investigated. The influence of the tool rotation speed, welding speed and applied load was studied. The friction stir welding (FSW) was conducted at welding speed ranged from 30 to 70 mm/ min, rotation speed ranged from 400 to 1200rpm and applied load ranged from 1000 to 1500 kg. After welding process, tensile and Vickers hardness tests were performed. It has been found that increasing the tool rotational speed and/or reducing the welding speed increases heat input and causes grain coarsening in stir zone. High applied load refines the microstructure of NZ and increases the hardness and tensile strength of NZ. An optimum heat input condition was found to reach the best mechanical properties of the joints. The tensile characteristics of the friction stir welded tensile samples depend significantly on the tool rotation speed ,welding speed and applied load.

Effect of Friction Stir Welding pin Shape on Mechanical Properties of AA6061 Alloy Weldment

2013 ◽  
Vol 465-466 ◽  
pp. 1309-1313
Author(s):  
Mohd Hasbullah Idris ◽  
Mohd Shamsul Husin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Friction Stir Welding ◽  
Material Flow ◽  
Weld Line ◽  
Butt Joint ◽  
Hardness Distribution ◽  
Plunge Depth ◽  
Friction Stir ◽  
Joint Properties

The present study is aimed to determine the effect of friction stir welding pin; square and diamond shape on mechanical properties of butt joint AA6061 weldment. Welding was carried out at different plunge depths of 0.0, 0.2, 0.3 and 0.4 mm together with rotation and transverse speeds of 500 rpm and 40 mm/min, respectively. Material flow, tensile strength and hardness of the weldment were evaluated. The results indicated that joint properties were significantly affected by tool design. It was found that material flow was higher for diamond pin tool compared to that of square pin resulting in considerable increased in tensile strength of the joint. In addition, the highest tensile strength was obtained on the samples welded with square shape pin at 0.4 mm plunge depth whilst the lowest was by diamond shape at the plunge depth of 0.0 mm. Regardless of pin shape and plunge depth; asymmetrical hardness distribution was observed for all weldments. The highest hardness was found to be close to the weld line produced by the diamond shaped pin at 0.0 mm plunge depth.

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