Friction Stir Lap Welding of Aluminum to Steel Using Refractory Metal Pin Tools

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
M. Shamsujjoha ◽  
Bharat K. Jasthi ◽  
Michael West ◽  
Christian Widener
Keyword(s):  
Mechanical Properties ◽  
Refractory Metal ◽  
Joint Strength ◽  
Joint Interface ◽  
Friction Stir Lap Welding ◽  
Plunge Depth ◽  
Friction Stir ◽  
Joint Efficiency ◽  
Bonding Area ◽  
Lap Welding

Steel and Al were friction stir lap welded using two different W-25% Re-4% HfC pin tools, having two different pin diameters and pin lengths. The effects of plunge depth, bonding area, and top sheet positions on the microstructure and mechanical properties were investigated. Morphology of the joint interface showed severe steel flash on the retreating side, which controlled the joint strength when the top sheet was placed on the retreating side. A joint efficiency of 58% was achieved when right-handed lap welds were made using the pin tool with longer pin length.

Dissimilar Friction Stir Lap Welding of AA2198 and AA7075 Sheets: Forces, Microstructure and Mechanical Properties

2021 ◽  
Author(s):  
Antonello Astarita ◽  
Fausto Tucci ◽  
Alessia Teresa Silvestri ◽  
Michele Perrella ◽  
Luca Boccarusso ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Welding Process ◽  
Processing Parameters ◽  
Processing Parameter ◽  
Friction Stir Lap Welding ◽  
Friction Stir ◽  
Lap Shear ◽  
Microstructure And Mechanical Properties ◽  
Lap Welding ◽  
Factorial Design Of Experiments

Abstract This paper deals with the dissimilar friction stir lap welding of AA2198 and AA7075 sheets. The influence of processing parameters, namely welding speed and tool rotational speed on joint features, microstructure, and mechanical properties were investigated implementing a full factorial design of experiments. During the welding process, axial and transversal forces were continuously measured using a dedicated sensed fixture aiming at the correlation of this processing parameter with the quality of the achieved joints. The reported outcomes showed a very narrow processing window in which it was possible to avoid the formation of defects while the formation of an hook was observed for all the joints welded. The influence of the weld bead morphology on the lap shear strength was elucidated proving that the strength is ruled by the hook morphology. A correlation between the process parameters and the forces arising was also attempted. The final microstructure of the joints was studied and explained and also compared with the microhardness results.

Friction Stir Lap Welding of Thin AA6061-T6 and AISI304 Sheets at Different Values of Pin Penetrations

2018 ◽  
Author(s):  
Raju Prasad Mahto ◽  
Surjya K. Pal
Keyword(s):  
Intermetallic Compound ◽  
Joint Strength ◽  
Detrimental Effect ◽  
Steel Substrate ◽  
Weld Strength ◽  
Steel Matrix ◽  
Friction Stir Lap Welding ◽  
Depth Of Penetration ◽  
Friction Stir ◽  
Lap Welding

The present paper focuses on the influence of pin penetration on joint strength achieved in friction stir lap welding between AA6061-T6 and AISI304. Penetration of pin into the steel substrate, which is placed below the aluminium, has an influencing role in achieving a good weld. Beyond a certain depth of penetration of pin into the steel, non-uniform thicker intermetallic compound and the weld defects have been found. Defects were found to be located in the stir zone. Thus, an excessive penetrations of the pin into the steel matrix has been produced a detrimental effect to the weld strength. An optimum penetration of pin has been experimentally found out.

scholarly journals Performance of Plunge Depth Control Methods During Friction Stir Welding

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 283 ◽  
Author(s):  
Jinyoung Yoon ◽  
Cheolhee Kim ◽  
Sehun Rhee
Keyword(s):  
Friction Stir Welding ◽  
Position Control ◽  
Longitudinal Direction ◽  
Control Methods ◽  
Friction Stir Lap Welding ◽  
Plunge Depth ◽  
Friction Stir ◽  
Compensation Control ◽  
Depth Control ◽  
Lap Welding

Friction stir welding is a preferred solid state welding process for Al/Fe joints, and in friction stir lap welding, the plunge depth is the most critical parameter for joint strength. We compared three plunge depth control methods, namely conventional position control, offset position control, and deflection compensation control in the friction stir lap welding of 3 mm-thick Al 5083-O alloy over 1.2 mm-thick DP 590 steel. The desired plunge depth was 0.2 mm into the steel sheet. However, the pin did not reach the steel surface under conventional position control due to deflection of the vertical axis of the welding system. In offset position control, an additional offset of 0.35 mm could achieve the desired plunge depth with considerable accuracy. Nevertheless, a gradual increase of the plunge depth along the longitudinal direction was unavoidable, due to an in-situ decrease of the material yield strengths. In deflection compensation control, the deflection is estimated by the coaxially measured plunging force and the force-deflection relationship, and then corrected by feedback control. Thus, the plunge depth is stabilized along the longitudinal direction and is precisely controlled with a 3.3-μm standard deviation of error during the tool traverse phase. There is also a consistent bias of 32 μm caused by the resolution of the measuring system, and it can be easily calibrated in the feedback control system.

scholarly journals Interface Characteristics and Mechanical Properties of Ultrasonic-Assisted Friction Stir Lap Welded 7075-T6 Aluminium Alloy

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5335 ◽  
Author(s):  
Changshu He ◽  
Zhiqiang Zhang ◽  
Ying Li ◽  
Jingxun Wei ◽  
Menggang Zhai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ultrasonic Vibration ◽  
Fracture Mode ◽  
Fracture Strength ◽  
Shear Fracture ◽  
Friction Stir Lap Welding ◽  
Friction Stir ◽  
Ultrasonic Assisted ◽  
Lap Welding ◽  
Cold Lap

In this work, friction stir lap welding (FSLW) and ultrasonic-assisted friction stir lap welding (UAFSLW) was applied to 6-mm-thick 7075-T6 alloy sheets using three welding tools with the same process parameters. The joint formation, microstructural characteristics, and mechanical properties of the resulting lap joints were then investigated. The results showed that ultrasonic vibration significantly promoted the flow of metal at the interface, enlarged the size of the stirred zone (SZ), and reduced the angle between the hook defect and the interface. During lap shear testing, the FSLW and UAFSLW joints fractured in a similar manner. The fracture modes included tensile fracture, shear fracture, and a mixture of both. Cold lap and hook defects may have served as crack-initiation zones within the joint. Under configuration A (i.e., upper sheet on the retreating side (RS)), all joints failed in the shear-fracture mode. The effective lap width (ELW) of the joint welded using tool T2 was the greatest. This resulted in a higher shear fracture strength. The maximum shear fracture strength of the UAFSLW joint was 663.1 N/mm. Under configuration B (i.e., upper sheet on the advancing side (AS)), the shear fracture strength was greatly affected by the fracture mode. The highest shear fracture strength of the UAFSLW joint, 543.7 N/mm, was welded by tool T3. Thus, under otherwise identical conditions, UAFSLW joints can withstand a greater fracture shear strength than FSLW joints, as ultrasonic vibration helps to mix the material at the interface, thus, enlarging the SZ and diminishing the cold lap defects.

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