Influence of Pin Length and Electrochemical Platings on the Mechanical Strength and Macroscopic Defect Formation in Stationary Shoulder Friction Stir Welding of Aluminium to Copper

In this study, 2A14-T4 Al-alloy T-joints were prepared via stationary shoulder friction stir welding (SSFSW) technology where the stirring pin’s rotation speed was set as different values. In combination with the numerical simulation results, the macro-forming, microstructure, and mechanical properties of the joints under different welding conditions were analyzed. The results show that the thermal cycle curves in the SSFSW process are featured by a steep climb and slow decreasing variation trends. As the stirring pin’s rotation speed increased, the grooves on the weld surface became more obvious. The base and rib plates exhibit W- or N-shaped hardness distribution patterns. The hardness of the weld nugget zone (WNZ) was high but was lower than that of the base material. The second weld’s annealing effect contributed to the precipitation and coarsening of the precipitated phase in the first weld nugget zone (WNZ1). The hardness of the heat affect zone (HAZ) in the vicinity of the thermo-mechanically affected zone (TMAZ) dropped to the minimum. As the stirring pin's rotation speed increased, the tensile strengths of the base and rib plates first increased and then dropped. The base and rib plates exhibited ductile and brittle/ductile fracture patterns, respectively.

Download Full-text

Prediction of Surface Profile in Friction Stir Welding Using Coupled Eulerian and Lagrangian Method

Volume 11: Heat Transfer and Thermal Engineering ◽

10.1115/imece2020-23193 ◽

2020 ◽

Author(s):

Debtanay Das ◽

Swarup Bag ◽

Sukhomay Pal ◽

M. Ruhul Amin

Keyword(s):

Friction Stir Welding ◽

Surface Morphology ◽

Process Parameters ◽

Chip Formation ◽

Material Flow ◽

Defect Formation ◽

Current Model ◽

Surface Profile ◽

Green Technology ◽

Friction Stir

Abstract Friction stir welding (FSW) is widely accepted by industry because of multiple advantages such as low-temperature process, green technology, and capable of producing good quality weld joints. Extensive research has been conducted to understand the physical process and material flow during FSW. The published works mainly discussed the effects of various process parameters on temperature distribution and microstructure formation. There are few works on the prediction of defect formation from a physics-based model. However, these models ignore chip formation or surface morphology and material loss during the FSW process. In the present work, a fully coupled 3D thermo-mechanical model is developed to predict the chip formation and surface morphology during welding. The effects of various process parameters on surface morphology are also studied using the current model. Coupled Eulerian-Lagrangian (CEL) technique is used to model the FSW process using a commercial software ABAQUS. The model is validated by comparing the results in published literature. The current model is capable of predicting the material flow out of the workpiece and thus enables the visualization of the chip formation. The developed model can extensively be used to predict the surface quality of the friction stir welded joints.

Download Full-text

Material flow and void defect formation in friction stir welding of aluminium alloys

Science and Technology of Welding & Joining ◽

10.1080/13621718.2018.1471844 ◽

2018 ◽

Vol 23 (8) ◽

pp. 677-686 ◽

Cited By ~ 12

Author(s):

X. H. Zeng ◽

P. Xue ◽

D. Wang ◽

D. R. Ni ◽

B. L. Xiao ◽

...

Keyword(s):

Friction Stir Welding ◽

Aluminium Alloys ◽

Material Flow ◽

Defect Formation ◽

Void Defect ◽

Friction Stir

Download Full-text

Multi-objective Optimization of Submerged Friction Stir Welding Process Parameters for Improved Mechanical Strength of AA6061 Weld Bead by Using Taguchi-L18-Based Gray Relational Analysis

Advances in Applied Mechanical Engineering - Lecture Notes in Mechanical Engineering ◽

10.1007/978-981-15-1201-8_103 ◽

2020 ◽

pp. 965-973

Author(s):

Laxmana Raju Salavaravu ◽

Lingaraju Dumpala

Keyword(s):

Friction Stir Welding ◽

Mechanical Strength ◽

Process Parameters ◽

Welding Process ◽

Weld Bead ◽

Gray Relational Analysis ◽

Multi Objective Optimization ◽

Friction Stir ◽

Multi Objective ◽

Relational Analysis

Download Full-text

A Comparative Investigation on Conventional and Stationary Shoulder Friction Stir Welding of Al-7075 Butt-Lap Structure

Metals ◽

10.3390/met9121264 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1264 ◽

Cited By ~ 1

Author(s):

Yu Chen ◽

Huaying Li ◽

Xiaoyu Wang ◽

Hua Ding ◽

Fenghe Zhang

Keyword(s):

Friction Stir Welding ◽

Material Flow ◽

Comparative Investigation ◽

Flow Mode ◽

Nugget Zone ◽

Friction Stir ◽

Stationary Shoulder ◽

Average Grain Size ◽

Al 7075

Both conventional friction stir welding (C-FSW) and stationary shoulder friction stir welding (S-FSW) were employed to join the Al-7075 butt-lap structure, then the microstructural evolution and mechanical characterization of all FSW joints were systematically studied. The C-FSW joint exhibited a rough surface with flashes and arc corrugations, while the surface of the S-FSW joint became smooth. Moreover, for the S-FSW joint, the shoulder-affected zone got eliminated and the material flow mode during FSW was changed owning to the application of stationary shoulder. Furthermore, in comparison to C-FSW, the lower welding heat input of S-FSW decreased the average grain size in the nugget zone and inhibited the coarsening of strengthening precipitates in the heat-affected zone, elevating the overall hardness for the S-FSW joint. In addition, the tensile strength of the S-FSW joint became higher compared to the C-FSW joint, and all the FSW joints failed inside the nugget zone attributing to the existence of hook defect. The sharp-angled hook defect deteriorated the plasticity of the C-FSW joint further, which was only 70% that of the S-FSW joint.

Download Full-text