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.

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.

scholarly journals The Preliminary Exploration of Micro-Friction Stir Welding Process and Material Flow of Copper and Brass Ultra-Thin Sheets

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2401
Author(s):  
Changqing Zhang ◽  
Zhuo Qin ◽  
Chen Rong ◽  
Wenchen Shi ◽  
Shuwen Wang
Keyword(s):  
Friction Stir Welding ◽  
Flow Behavior ◽  
Pure Copper ◽  
Weld Zone ◽  
Metal Flow ◽  
Welding Process ◽  
Process Conditions ◽  
Friction Stir ◽  
Plastic Metal ◽  
Tool Pin

In the friction stir welding (FSW) of ultra-thin dissimilar metal sheets, different physical material properties, the reduction of plastic metal in the weld zone, and insufficient plastic metal flow lead to poor weld seam shapes and joint qualities. Therefore, it is necessary to study the flow behavior during the FSW of ultrathin sheets. In this study, micro friction stir welding (μFSW) was conducted and analyzed for the butt welding of 0.6-mm-thick ultrathin brass (H62-H) and pure copper (T2-Y) sheets. By analyzing the electric signals of the temperature and force during the welding process, testing the mechanical properties, and analyzing the metallography of the joint, the influences of the process parameters on the metal flow behavior during μFSW were studied. In the proper process conditions, the material preferentially migrated and concentric vortex flow occurred in the vicinity of the shoulder and tool pin action areas. The copper was pushed from the retreating side (RS) to the advancing side (AS) of the weld, allowing it to flow more fully. A mixture of both materials formed at the bottom of the weld nugget, and less migration occurred in the heat-affected zone of the AS at this time. The highest tensile strength can reach 194 MPa, accounting for 82.6% of the copper. The presence of brittle phases Cu5Zn8, AgZn3 and AgZn caused the hardness to fluctuate slightly.

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.

Influence of Tool Geometry and Contact Condition on Friction Stir Welding of Al-Cu Laminated Composites

2013 ◽  
Vol 856 ◽  
pp. 16-21
Author(s):  
R. Beygi ◽  
Mohsen Kazeminezhad ◽  
A.H. Kokabi ◽  
S. Mohammad Javad Alvani ◽  
D. Verdera ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Laminated Composites ◽  
Flow Behavior ◽  
Tool Geometry ◽  
Contact Conditions ◽  
Friction Stir ◽  
Tool Geometries ◽  
Welding Procedure ◽  
Sem Analyses

In this study friction stir welding of Al-Cu laminated composites were carried out by two different tool geometries. Welding procedure was carried out from both sides of Al and Cu. Analyzing cross section of welds showed that different contact conditions between shoulder and material, offers different material flow behavior which is dependent on the tool geometry. SEM analyses showed that mixing of materials in nugget region is more pronounced in the advancing side. Also XRD results indicated that welding from Cu side, leads to intermetallic formation in mixed regions.

Material Flow Behavior during Friction Stir Welding of Copper and Steel

2011 ◽  
Vol 138-139 ◽  
pp. 842-847 ◽  
Author(s):  
Chun Ping Huang ◽  
Wen Liang Chen ◽  
Li Ming Ke ◽  
Huang Lu
Keyword(s):  
Friction Stir Welding ◽  
Material Flow ◽  
Flow Behavior ◽  
Dissimilar Metals ◽  
Screw Thread ◽  
Friction Stir ◽  
Different Shapes ◽  
Welding Joints ◽  
Flow Morphology ◽  
Main Factor

The joining of dissimilar metals, T2 copper and Q235 mild steel was carried out by friction stir welding. The material flow of different shapes of the probe and different forms of welding joints were studied, the material flow behavior on different locations from the probe was also analyzed. The experimental results showed that the screw thread in probe is the main factor in driving material flow along the thickness direction of the weld during FSW of copper and steel, the flow morphology of the weld is significantly different with vary forms of welding joints, and the material flow on different locations from the probe are quite different from each other. Instantaneous cavity will form at the upper of the weld with the use of left screw thread probe during FSW, and if not promptly and adequate padding, it is prone to appear hole-type defects.

scholarly journals Material-flow behavior during friction-stir welding of 6082-T6 aluminum alloy

2016 ◽  
Vol 87 (1-4) ◽  
pp. 1115-1123 ◽  
Author(s):  
Yongxian Huang ◽  
Yaobin Wang ◽  
Long Wan ◽  
Haoshu Liu ◽  
Junjun Shen ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Friction Stir Welding ◽  
Material Flow ◽  
Flow Behavior ◽  
Friction Stir

scholarly journals A Multi Scale Strategy for Simulation of Microstructural Evolutions in Friction Stir Welding of Duplex Titanium Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 485-497 ◽  
Author(s):  
Z. Zhang ◽  
Z. J. Tan
Keyword(s):  
Friction Stir Welding ◽  
Volume Fraction ◽  
Average Length ◽  
Transformation Model ◽  
Scale Model ◽  
Welding Temperature ◽  
Rotating Speed ◽  
Friction Stir ◽  
Multi Scale ◽  
Translational Speed

AbstractA fully coupled thermo-mechanical model is established to simulate the temperature variations and the material deformations in friction stir welding (FSW) of Ti-6Al-4V. The extracted data are used for further simulation on microstructural evolutions. A multi scale model, which consists of the grain growth model in grain cluster scale and the phase transformation model in one grain scale, is proposed. The nuclei of α and β phases, the recrystallizations and the grain growths are systematically investigated. Comparisons with experimental data and experimental observations can validate the newly proposed microstructural evolution model for Ti-6Al-4V. Results indicate that the volume fractions of α and β phases can be directly determined by the cooling rates in FSW process. With the increase of the rotating speed, the volume fraction of α phase is increased and β phase decreased due to the increase of welding temperature. With the decrease of the translational speed, the volume fraction of α phase gets bigger and β phase smaller. The acicular α grain can be generated on the β grain boundaries and grows along <1 1 0> direction on β substrate. The average length of α grain can be increased with longer cooling time and decreased with lower rotating speed or higher translational speed.

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