scholarly journals Microstructure and Mechanical Properties of 6061 Al/AZ31 Mg Joints Friction Stir Lap Welded by a Tool with Variable-Pitch Thread Pin

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Changshu He ◽  
Chengpeng Qiu ◽  
Zhiqiang Zhang ◽  
Jingxun Wei ◽  
Hao Zhang ◽  
...  
Keyword(s):  
Rotation Speed ◽  
Ring Structure ◽  
Mg Alloy ◽  
Al Alloy ◽  
Mechanical Interlocking ◽  
Tensile Shear ◽  
Variable Pitch ◽  
Friction Stir ◽  
Bottom Interface ◽  
Onion Ring

Sheets of 6061-T6 aluminum alloy (thickness = 3 mm) and AZ31 magnesium alloy were friction stir lap welded by a tool with a variable-pitch thread pin (coarse-threaded in the upper part and fine-threaded in the lower part). For the same rotation speed and welding speed, the heat input was higher in joints with an upper Al alloy (Configuration Al-Mg) than in those with an upper Mg alloy (Configuration Mg-Al). In Configuration Al-Mg, these two dissimilar metals were poorly mixed and Al dominated the stirred zone (SZ). Many intermetallic compounds (IMCs) of Al3Mg2 formed inside the SZ. In Configuration Mg-Al, Mg alloy bands, flocculent Al12Mg17 bands, and minor Al alloy bands intersected in the SZ, forming a complex onion-ring structure. Moreover, a complex mechanical interlocking structure developed at the bottom interface of the SZ. The maximum tensile shear strengths of the Al-Mg and Mg-Al lap configurations were 160.3 and 217 N/mm, respectively, at 700 rpm. The higher tensile shear strength of the Mg-Al configuration primarily represented less IMCs and complex mechanical interlocking structures in the SZ.

scholarly journals Effect of Stirring Pin Rotation Speed on Microstructure and Mechanical Properties of 2A14-T4 Alloy T-Joints Produced by Stationary Shoulder Friction Stir Welding

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1938
Author(s):  
Haifeng Yang ◽  
Hongyun Zhao ◽  
Xinxin Xu ◽  
Li Zhou ◽  
Huihui Zhao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Friction Stir Welding ◽  
Rotation Speed ◽  
Weld Nugget ◽  
Al Alloy ◽  
Nugget Zone ◽  
T Joints ◽  
Friction Stir ◽  
Stationary Shoulder ◽  
Microstructure And Mechanical Properties

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.

Microstructure evolution mechanism of Al/Mg dissimilar joint during friction stir welding

2020 ◽  
Vol 117 (3) ◽  
pp. 311 ◽  
Author(s):  
Wei Chen ◽  
Wenxian Wang ◽  
Zepeng Liu ◽  
Decheng An ◽  
Ning Shi ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Flow Pattern ◽  
Microstructure Evolution ◽  
Ring Structure ◽  
Reflection Effect ◽  
Nugget Zone ◽  
Friction Stir ◽  
Flow Features ◽  
Differential Etching ◽  
Onion Ring

A butt friction stir welding (FSW) process was performed on 6061 Al and AZ31 Mg plates. The microstructure evolutions of the three main regions in the nugget zone (NZ) retained in the FSW joint were systematically investigated to clarify the joint formation mechanism during FSW. The differential etching of these microstructural features was found to produce very vivid flow features. During FSW, the material in the shoulder affected zone (SAZ) was mainly driven by the shoulder, and only a small amount of it was driven by the pin. A strip of Al transferred by the pin from the retreating side (RS) to the advancing side (AS) contacted and reacted with Mg, thus forming intermetallic compounds (IMCs) (e.g., Mg17Al12 and Al3Mg2). Due to the stirring action and tilted angle of the threaded pin, a banded structure (BS) feature tilted at approximately 45° was produced by the alternating lamellae of IMCs. The appearance of an onion ring structure occurred in the severely deformed zone (SDZ), which could be attributed to the reflection effect of the imaginary die wall. Finally, the overall flow pattern of the joint was obtained.

Effects of process time and thread on tensile shear strength of Al alloy lap joint produced by friction stir spot welding

2010 ◽  
Vol 24 (3) ◽  
pp. 169-175 ◽  
Author(s):  
Mitsuo Fujimoto ◽  
Daisuke Watanabe ◽  
Natsumi Abe ◽  
Sato S. Yutaka ◽  
Hiroyuki Kokawa
Keyword(s):  
Shear Strength ◽  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Process Time ◽  
Al Alloy ◽  
Tensile Shear Strength ◽  
Lap Joint ◽  
Tensile Shear ◽  
Friction Stir

Cracking and Local Melting in Mg-Alloy and Al-Alloy During Friction Stir Spot Welding

2008 ◽  
Vol 52 (9-10) ◽  
pp. 38-46 ◽  
Author(s):  
M. Yamamoto ◽  
A. Gerlich ◽  
T. H. North ◽  
K. Shinozaki
Keyword(s):  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Mg Alloy ◽  
Al Alloy ◽  
Local Melting ◽  
Friction Stir

Effect of Tool Speeds during Friction Stir Lap Welding on Mode of Fracture and Fracture Strength of Al 6060-T5 Joints

2011 ◽  
Vol 275 ◽  
pp. 77-80 ◽  
Author(s):  
Shamzin Yazdanian ◽  
Zhan W. Chen ◽  
Guy Littlefair
Keyword(s):  
Fracture Strength ◽  
Welding Speed ◽  
Rotation Speed ◽  
Al Alloy ◽  
Zone Size ◽  
Friction Stir Lap Welding ◽  
Friction Stir ◽  
A Value ◽  
Maximum Value ◽  
Lap Welding

Friction stir lap welding (FSLW) of an age hardened Al alloy and evaluations of how FS speeds affected hooking and how hooking and softening due to FS affected fracture strength of the lap welds have been conducted. It was found that increasing rotation speed () and reducing welding speed (v) increased the stir zone size (AB-SZ) and also hook size (h), although a maximum value of h (hMax) reached. The features of hooks for the observed (,v)- AB-SZ-h relationships are presented and explained. It was found that when h increased to a value of ~ 0.9 mm (for the 3 mm alloy sheets), it started to invoke a significant effect on reducing fracture strength. Factors such as FS softening and insufficient joining, limited the fracture strength of the lap welds for small h values and these are presented and discussed.

Effect of tool pin geometry on microstructure and mechanical properties of friction stir spot welds of 7075-T651 aluminium alloy

2021 ◽  
Vol 118 (1) ◽  
pp. 110
Author(s):  
Omer Ekinci ◽  
Zulkuf Balalan
Keyword(s):  
Aluminium Alloy ◽  
Fracture Mode ◽  
Impact Energy ◽  
Rotation Speed ◽  
Tensile Shear ◽  
Spot Welds ◽  
Friction Stir ◽  
Tool Rotation Speed ◽  
Shear Loads ◽  
Tool Rotation

7075-T651 aluminium alloy sheets were overlapped and friction stir spot welded using two welding tools having different pin geometries (one with a conical pin and other with a triangular pin) and 800, 1200 and 1600 revolution per minute (rpm) tool rotation speeds at a constant tool plunge and removal speed of 7.3 mm/min, tool plunge depth of 3.8 mm and tool dwell time of 5 s. Microstructure, Vickers microhardness, tensile shear strength, fracture surface after tensile shear test and impact energy of the produced friction stir spot welds were examined. As a result, the welds made via triangular pin tool had considerably higher tensile shear loads than the welds made via conical pin tool since the weld bond widths (stir zones) of the welds made via triangular pin tool were larger. The strongest welds made at 1200 rpm for conical pin tool and triangular pin tool. The tensile shear loads of the welds increased significantly when tool rotation speed increased from 800 to 1200 rpm for both welding tools and then decreased slightly for triangular pin tool and dramatically for conical pin tool with further increasing tool rotation speed from 1200 to 1600 rpm. Maximum tensile shear load of 7.776 kN and impact energy of 16 J obtained in the weld made at 1200 rpm using triangular pin tool. The welds made at 800 rpm had lowest impact energy. The lowest hardness values found in the heat affected zones of the welds. Circumferential fracture mode for conical pin tool welds and nugget pull-out fracture mode for triangular pin tool welds observed after tensile tests.

Microstructure and mechanical properties of 6061-T6 aluminum alloy and Q235 steel via probeless friction stir extrusion joining

2021 ◽  
Author(s):  
Peng Zhang ◽  
Shengdun Zhao ◽  
Chuanwei Zhang ◽  
Zheng Chen ◽  
Jiaying Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Composite Structures ◽  
Rotation Speed ◽  
Shear Loading ◽  
Tensile Shear ◽  
Q235 Steel ◽  
Friction Stir ◽  
Fracture Failure ◽  
Friction Stir Extrusion

Abstract Aluminum alloy and steel composite structures are increasingly and widely used in the automotive industry and other fields owing to their advantages of light weight and high comprehensive performance. The high-quality joining of aluminum alloy and steel has become the research focus in China and overseas. The current study proposes a probeless friction stir extrusion joining (P-FSEJ) process to avoid intermetallic compounds, reduce wear of tools, and obtain a spot joint without keyhole defects. Strong mechanical interlock is formed after that the plasticized aluminum alloy (AA) 6061-T6 is extruded into the prefabricated threaded hole of a Q235 steel plate in the P-FSEJ process. Three distinct zones in the typical symmetrical “basin-shaped” P-FSEJed joint are observed. In addition to the rotation speed, the diameter of the threaded hole is also specifically used to study the influence on the mechanical properties of the joint. When the rotation speed is 1200 rpm, the maximum tensile-shear loads of the M6 and M7 threaded hole joints are 2882.93 N and 3344.74 N, respectively, while the M8 threaded hole joint is 4139.58 N at rotation speed of 1000 rpm. Two typical fracture failure modes of the P-FSEJed joints, namely, rivet shear and rivet pullout-shear fractures, are obtained under tensile-shear loading. Lastly, the P-FSEJed joints with mode “P” fracture failure generally have high strength and energy absorption capability.

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