Microstructures and Properties of FSW Joints of AZ31B Mg Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 855-859 ◽  
Author(s):  
Si Rong Yu ◽  
Xian Jun Chen

The extruded AZ31B Mg alloy sheet was welded with friction stir welding. The microstructures and mechanical properties of the welded joint were investigated. The results show that the grains in the weld nugget zone were small, uniform and equiaxed. The grains in thermo-mechanical affected zone were stretched and relatively small, but were not as small and uniform as those in the weld nugget zone. The grains in the heat-affected zone were relatively coarse. The fracture of the welded joint occurred mainly in the heat affected zone. The tensile strength of the welded joints was up to 257.4 MPa and was 87.9% of the base material strength. The microhardness in the weld nugget zone was higher. The microhardness in the thermo-mechanical affected zone and heat affected zone were lower than that in the weld nugget zone. The microhardness in the weld nugget zone increased from the upper surface to the bottom.

2021 ◽  
Vol 71 (2) ◽  
pp. 299-304
Author(s):  
Srinivasa Rao Mallipudi ◽  
Tangudu Sai Shankar ◽  
Perumalla Srikar ◽  
Uppda Bhanoji Rao ◽  
Yandra Chandrasekhar ◽  
...  

Abstract In this study, friction stir welding (FSW) and Tungsten gas welding (TIG) processes were used to weld 5 mm thick Al-4.2Mg-0.6Mn-0.4Sc-0.1Zr alloy plates. The FSwelds and TIG welds were tested for mechanical properties (hardness, ultimate tensile strength, bending strength and impact strength) by means of vicker’s hardness machine, universal testing machine and impact test machine respectively. The strength of the base material was higher, compared to the strength of the FSW and TIG welded joints. The strength of the TIG welded joint decreased, compared to the strength of the FSW welded joint. The microstructure features were also observed for base material with the aid of metallurgical microscope and compared the same with the microstructures of FSW and TIG welded joints. FSW change the material strength due to fine-grain refinement in the stir zone in Al-4.2Mg-0.6Mn-0.4Sc-0.1Zr alloy and therefore FS welded joint exhibited 91.6% joint efficiency followed by the TIG welded joint of 69.8%.


Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1938
Author(s):  
Haifeng Yang ◽  
Hongyun Zhao ◽  
Xinxin Xu ◽  
Li Zhou ◽  
Huihui Zhao ◽  
...  

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.


2014 ◽  
Vol 496-500 ◽  
pp. 110-113
Author(s):  
Dong Gao Chen ◽  
Jin He Liu ◽  
Zhi Hua Ma ◽  
Wu Lin Yang

The7A05 aluminum alloy of the 10mm thickness was welded by the friction stir welding. The microstructure and mechanical Properties of the welded joint was researched by the optical microscope, etc. The results showed: the microstructure of the weld nugget zone and the thermal mechanically affected zone were refined as the welding speed increasing when the rotate speed is constant. As the welding speed increasing the strength of extension of the welded joint is increasing at first and then stable basically. but the yield strength had no obvious change.


2011 ◽  
Vol 189-193 ◽  
pp. 3335-3338
Author(s):  
Ge Ping Liu ◽  
Yu Hua Chen ◽  
Hong Yan Wu ◽  
Li Ming Ke

ZL114A was joined by friction stir welding and liquid nitrogen was used to cool the welded joint during the welding process. The Influence of forced cooling on the microstructure and properties of welded jointed was studied. The results show that, when forced cooling is used, the amount of silicon particles in weld nugget zone is larger and the size is more homogeneous, the size of silicon particle in heat-mechanical affected zone is more fine , the grain size of heat affected zone is half of air cooling welded joint and the amount of Al-Si eutectic is smaller than air cooling welded joint. The micro hardness increases after forced cooling is used, the hardness of weld nugget zone is 20Hv higher than air cooling welded joint. The strength of forced cooling welded joint increases 13.6% than air cooling welded joint.


2018 ◽  
Vol 25 (6) ◽  
pp. 1219-1228
Author(s):  
Her-Yueh Huang ◽  
Chung-Wei Yang ◽  
Wen-Yao Deng

AbstractThe main objective of the present work was to establish a friction-stir-welding process to weld dissimilar metal joints on AA6082 and AA6066 aluminum alloy plates. Joints were made while varying tool rotation speed at a constant traveling speed and at the same time adding oxygen-free copper reinforcement inside the weld nugget for the purpose of analyzing the microstructural evolution and mechanical properties of the joint. Results showed that the morphology of the microstructure in the weld nugget changed significantly with rotation speed. Optical microscopy, scanning electron microscopy, and energy dispersive spectroscopy analyses revealed that oxygen-free copper particles could be uniformly dispersed into the weld nugget because of higher rotation speeds. Because of the presence of reinforcement particles homogenously distributed inside the nugget zone, the mechanical properties, such as ultimate tensile strength and hardness of weld joint, were greatly improved.


2011 ◽  
Vol 418-420 ◽  
pp. 1520-1523
Author(s):  
Yong Zhao ◽  
You Li Ye ◽  
Keng Yan ◽  
Li Long Zhou

Microstructures and mechanical properties of pure copper weld joints are discussed under different parameters of friction stir welding. The results reveal that it is conducive to the formation of compact joint in friction stir welding by applying high speed steel tool with high anti-bonding temperature. The friction stir welding joint with compact and defect-free microstructure could be obtained when the tool rotation rate is 1250- 1650 r/min and the tool traverse speed is 20-50 mm/min. Intensively plastic deformation occurs in the soften materials of the weld nugget zone and numerous crystal particles are broken under the influence of tool stirring. The microstructure of weld nugget zone is composed of tiny isometric crystals, which is due to the dynamic recrystallization of broken crystal particles. The structure of thermo-mechanical affected zone on both sides is asymmetric. Obvious boundary of the thermo affected zone could be seen on the advancing side, and the plastic streamline is apparent.


2012 ◽  
Vol 735 ◽  
pp. 192-197 ◽  
Author(s):  
Mohammad Albakri ◽  
Bilal Mansoor ◽  
Ahmad Albakri ◽  
Marwan Khraisheh

Friction stir process (FSP) is a severe plastic deformation based secondary processing technique that can be utilized to engineer novel microstructures in metallic alloys. It is well known that such techniques are cumbersome and require significant experimental work and material to determine optimum processing conditions. Therefore in this work, we propose a new two step numerical approach, where: (i) CFD simulations coupled with Zener-Holloman relation are used to predict microstructure evolution in stirred, transition and heat affected zones of friction stir processed AZ31 Mg alloy sheets, (ii) Finite element simulations are carried out to evaluate superplastic forming characteristics of different microstructures developed after FSP. Simulation trends including forming pressure profiles, dome height evolution, and thickness distribution of friction stir processed sheets are compared with those of the base material. The proposed combination of numerical approaches to model both processing and forming aspects yields a powerful tool to study and optimize processing and forming technologies with limited experimentation.


2015 ◽  
Vol 786 ◽  
pp. 111-115 ◽  
Author(s):  
Srinivasa Rao Pedapati ◽  
G. Vimalan ◽  
Mokhtar Awang ◽  
A.M.A. Rani

The mechanical properties of weld joints in Friction Stir Welding (FSW) are influenced by the welding parameters such as rotational speed, tool geometry and welding speed. In the present study, three different tool profiles have been used to weld the joints with three different rotational speed and two welding speeds. Full factorial experiments have been conducted using DoE. The mechanical properties of weld joint were evaluated by means of tensile tests and hardness test at room temperature. The experiment result shows that the average highest number of hardness was 40.06 HRB with square tool at a rotational speed of 2000rpm while lowest hardness was 30.84 HRB with cylindrical threaded tool at rotational speed of 1800rpm. The maximum tensile strength of the joint obtained is 265 M Pa which is close to base material strength. It is observed from experimental results that joints made by square tool yield more strength compared to other tool profiles.


2011 ◽  
Vol 189-193 ◽  
pp. 3560-3563
Author(s):  
Yu Wen Tian ◽  
Fei Xu ◽  
Wen Ya Li ◽  
Zhong Bin Tang

The distribution of mechanical property in the weld zone of friction stir welded 7050 aluminum alloy joint along the plane perpendicular to the welding direction was experimentally investigated by the non-contact measurement method. The results show that the elastic modulus presents a W-shape distribution across the weld zone. The elastic modulus in the weld nugget zone is increased due to the grain refinement. In addition, the elastic modulus in the advancing side is slightly less than that in the retreating side possibly because of the relatively higher temperature in the advancing side during the welding process. The strength in the vicinity of weld center is decreased while the ductility is enhanced. The tensile strength and yield strength in the weld nugget zone and thermo-mechanically affected zone are significantly decreased while the elongation is increased due to the change of strengthening mechanism. In the heat affected zone the strength is decreased compared to the base material because the second phase grows up.


2012 ◽  
Vol 602-604 ◽  
pp. 608-611
Author(s):  
Di Qiu He ◽  
Rui Lin Lai ◽  
Shao Hua Xu ◽  
Kun Yu Yang ◽  
Shao Yong Ye ◽  
...  

In this study, Cu-Cr-Zr alloy joints are successfully fabricated by friction stir welding (FSW). Defect-free weld are produced on 12mm thick Cu-Cr-Zr alloy plate useing a non-consumable tool with a specially designed and shoulder with a constant rotation speed and a fixed traverse speed. The effect of friction stir welding (FSW) on the microstructure and mechanical properties of Cu-Cr-Zr alloy joints are investigated in details: The joints showed the presence of various zones such as nugget zone (NZ) and thermo-mechanically affected zone (TMAZ) and base metal (BM), the microhardness and the tensile strength of welded joints are lower than that of the base material.


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