scholarly journals MANUFACTURING THINNED FRICTION-STIR WELDED 1050 ALUMINUM BY POST ROLLING: MICROSTRUCTURE AND MECHANICAL PROPERTIES

2021 ◽  
Vol 55 (5) ◽  
Author(s):  
Sina Zinatlou Ajabshir ◽  
Mohsen Kazeminezhad ◽  
Amir Hossein Kokabi

One of the friction-stir welding (FSW) limitations is joining thin sheets in sheet-metal manufacturing. To solve this limitation, thicker sheets can be welded with FSW and then rolled to a thinner thickness. This can improve the mechanical properties and save the weld zone soundly. In this work, 3-mm aluminum sheets were joined with FSW. The microstructure and mechanical properties of the samples were assessed at various rotational speeds (w) and travel speeds (v). Then, the welded samples were cold worked (CW) by rolling them at different percentages so that the samples were 2 mm and 1 mm thick. The effects of welding and post rolling on the mechanical properties and a failure analysis were deliberated. It was shown that welding reduces the transverse ultimate tensile strength (UTS) of FSWed samples by up to 29 % compared to the UTS of the base metal (BM), while rolling FSWed samples increased the UTS of the cold-worked FSWed samples by up to 94.7 % in comparison to the UTS of FSWed samples. Also, during the tensile test of the specimens FSWed at a lower travel speed, a fracture occurred at the stir zone (SZ)/thermo-mechanically affected zone (TMAZ) interface, on the advancing part; however, at a higher travel speed, it occurred at the interface of the heat-affected zone (HAZ) and TMAZ, on the retreating part. Moreover, during the tensile test of the cold-worked FSWed samples, the failure took place at the HAZ and the interface of the SZ and TMAZ, respectively. The UTS was risen by increasing the cold work. The UTS of a specimen FSWed at 50 mm/min and 1200 min–1 went up from 76 MPa to 124 MPa due to 33-% cold work and to 148 MPa due to 66-% cold work; meanwhile, the fracture occurred at the SZ/TMAZ interface or TMAZ of most of the post-rolled FSWed samples.

2010 ◽  
Vol 654-656 ◽  
pp. 1428-1431 ◽  
Author(s):  
Margarita Vargas ◽  
Sri Lathabai

Friction stir processing (FSP) was performed on AA 7075-T6, a heat treatable high strength Al-Zn-Mg-Cu alloy. The two main FSP parameters, the tool rotational and travel speed, were varied systematically in order to understand their influence on the microstructure and mechanical properties of the processed zone. At a given rotational speed, increasing the travel speed increased the microhardness of the nugget (stir) zone; for a given travel speed there appeared to be an optimum rotational speed which resulted in the highest microhardness. The range of FSP parameters used did not significantly influence the nugget zone grain size. It is suggested that the observed mechanical properties are a result of the complex interactions between the FSP thermo-mechanical effects and the processes of dissolution, coarsening and re-precipitation of the strengthening precipitates in this alloy.


2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Pashupati Pokharel ◽  
Yoonsang Kim ◽  
Sunwoong Choi

The microstructure and mechanical properties of the butt joint in high density polyethylene (HDPE) pipes were evaluated by preparing the joints with increasing the cooling time from 10 s to 70 s before pressure created for fusion of the pipes. Here, cold fusion flaws in HDPE butt joint were created with increasing the cooling time around 70 s caused by the close molecular contact followed by insufficient interdiffusion of chain segments back and forth across the wetted interface. The tensile failure mechanism of the welded pipes at different fusion time was projected based on the tensile test of dog-bone shaped, fully notched bar type as well as round U-notched specimens. The mechanical properties of the joints at different fusion time were correlated with the corresponding fracture surface morphology. The weld seam as well as tensile fracture surfaces were etched using strong oxidizing agents. The crystallinity of surface etched weld zone by potassium permanganate based etchant was found higher than unetched sample due to the higher susceptibility of amorphous phase of polyethylene with oxidizing agent. The U-notched tensile test of butt welded HDPE pipe and surface etching of the weldments provided clear delineation about the joint quality.


2016 ◽  
Vol 857 ◽  
pp. 266-270 ◽  
Author(s):  
Ho Sung Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo ◽  
Kyung Ju Min

Aluminum-copper-lithium alloy is a light weight metal that has been used as substitute for conventional aerospace aluminum alloys. With addition of Li element, it has lower density but higher strength. However these aluminum alloys are hard to weld by conventional fusion welding, since they often produce porosities and cracking in the weld zone. It is known that solid state welding like friction stir welding is appropriate for joining of this alloy. In this study, friction stir welding was performed on AA2195 sheets, in butt joint configuration in order to understand effects of process parameters on microstructure and mechanical properties in the weld zone. The results include the microstructural change after friction stir welding with electron microscopic analysis of precipitates.


2018 ◽  
Vol 786 ◽  
pp. 23-36
Author(s):  
Ahmed Ibrahim Abdel-Aziz ◽  
Ahmed S.A. Abou Taleb ◽  
Z.M. El-Baradie ◽  
Ahmed Ismail Zaky Farahat

Friction stir processing (FSP) is a solid-state technique for microstructural modification. The aim of this work is to evaluate the effect of input process parameters of friction stir processing (tool rotational speed rpm, travel speed mm/min) on microstructure and mechanical properties of A384 aluminum alloy. A384 aluminum alloy was cast using conventional stir casting process. The obtained alloy was subjected to friction stir process using different input parameters (rpm, mm/min) with double pass. Water was used as cooling medium during process. The microstructures of investigated alloys were characterized by optical, SEM microscopes, EDS and Map analyzer, while mechanical properties were evaluated by using tensile test. The results indicate that; after friction stir processing, the microstructure of as-cast alloy was greatly improved. Needle-like eutectic Si and Chinese Script a-Fe were modified to fine precipitates. Meanwhile, coarse primary Si and large plate b-Fe phase were dissolved. On the other hand, mapping analysis shows homogenous distribution of different alloying elements through the matrix. The higher values of tensile properties were obtained at 1200 rpm and 80 mm/min. UTS and YS were increased by 98% and50%, respectively. Meanwhile, ductility was approximately three times higher than that of cast alloy.


2019 ◽  
Vol 969 ◽  
pp. 720-726
Author(s):  
Ajay Kumar Revelly ◽  
B. Rajkumar ◽  
V. Swapna

The main aim of the present topic is friction stir welding (FSW) of Aluminium HE-30, which shows that improved microstructures, strong weld and with less of defects. In the other hand, an attempt was made to correlate the welding parameters and mechanical properties. In the present investigation four rotational speeds of 1000 rpm, 1200 rpm, 1400 rpm and 1600 rpm with travelling speed of 30 mm/min. and tool geometry (straight cylindrical) was chosen. It was observed that the tool rotational speed is a sensitive parameter to decide the ultimate tensile strength and yield strength of the present material. Similarly, the hardness of Al plates is improved at the weld zone. Hence, it is suggested that to consider a parameter such as welding tool rotational speed, travelling speed and materials in selecting the welding methods of sound joints, because it influences the microstructure and mechanical properties in various applications. In the present study, non-destructive tests are also confirmed the defective nature of the weld zone of Al plates.


Author(s):  
A.A. Saleh

Purpose: This work aims to investigate the microstructure and mechanical properties achieved by FSW of butt joints, namely of dissimilar sheets namely of 2014-T3 to 5059-H11 Al alloys by bonding the two materials perpendicular to their rolling directions. Design/methodology/approach: AA 2014T3 and AA 5059H11 were two dissimilar aluminium alloys friction stir welded. The joint has been examined in terms of hardness, microstructure, and mechanical properties. The microstructure of the weld area was characterized by using optical microscopy. Seven diverse regions of the microstructure in the joint can be illustrious. Findings: It has been noticed that a structure of fine grain is formed in the nugget region as a consequence of recrystallization. The thermos mechanically affected and heat affected zones of aluminium alloy 2014 are characterized by the lowest hardness values in spite of there are a general hardness decrease through the weld zone compared to both base metals. The ultimate tensile strength values of the dissimilar joint were found to be varying between 54% to 66% those of the base metal. Research limitations/implications: The t joining in FSW takes place with the base materials remnant in the solid state, which gives a considerable possibility to produce joints between the alleged difficult-to-weld heat treatable aluminium alloys. Originality/value: The outcomes display that friction stir welding can be effectively applied for the joining of dissimilar aluminium alloys.


Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 507 ◽  
Author(s):  
Changqing Zhang ◽  
Weijie Wang ◽  
Xin Jin ◽  
Chen Rong ◽  
Zhuo Qin

The welding tool is the key of micro friction stir welding (μFSW), which affects the heat input and the plastic forming of weld metal. In this paper, 0.8-mm-thick ultra-thin 1060-H24 aluminum sheets μFSW butt joints were used to compare and analyze the influence of the conventional tool and shoulderless tool on weld shaping, microstructure and mechanical properties. Besides, by measuring the axial force, transverse force and weld temperature in μFSW process, the influence of these two different tools on the heat input and metal flow mechanism of the weld were analyzed. The results show that the weld generated by the shoulderless tool has narrower width, less heat input and metal involved in plastic forming resulting in smaller HAZ (heat affected zone). The hardness of NZ (nugget zone) is obviously increased compared with that of the base metal. The highest tensile strength can reach 108.6 MPa, accounting for 78.6% of the base metal and 117.3% of the joint by the conventional tool. But the welding defects have to be overcome for industrial application of the shoulderless tool.


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