TY - JOUR

T1 - Experimental investigation of crack propagation mechanism in refill friction stir spot joints of AA6082-T6

AU - Becker, Niklaas

AU - dos Santos, Jorge F.

AU - Klusemann, Benjamin

N1 - Funding Information: This work was executed in frame of the TTP LB project LESSMAT, funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) , project number: 03LB2021D , which is gratefully acknowledged. We also acknowledge DESY for the use of beamline P07B from Helmholtz-Zentrum Hereon. Funding Information: This work was executed in frame of the TTP LB project LESSMAT, funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK), project number: 03LB2021D, which is gratefully acknowledged. We also acknowledge DESY for the use of beamline P07B from Helmholtz-Zentrum Hereon. Publisher Copyright: © 2024 The Author(s)

PY - 2024/4/16

Y1 - 2024/4/16

N2 - Since many aluminum alloys preferred in structural engineering can be welded conventionally only with great effort and energy input interest in alternative joining techniques is growing, such as solid state joining processes. In this work, the effect of refill friction stir spot welding (refill FSSW) on the crack propagation behavior in AA6082-T6 is studied. To be able to identify the individual fracture mechanism, refill FSSW was performed as a blind weld, i.e. only in one sheet designed as C(T)100 specimens. The vertical distance between notch and spot weld was varied and tested in two phases. First, a cyclic pre-crack was induced and then the specimen was caused to fail in quasi-static conditions, resulting in two different fracture modes. The results showed that the cyclic crack is dominated by residual stresses but the microstructure mainly influences the quasi-static crack propagation. It was also found that a stress concentration occurs in the transition area even without a hook. Furthermore, it was found that the crack propagation is not exclusively driven by the local strength but also by the angle at which the crack hits the spot weld.

AB - Since many aluminum alloys preferred in structural engineering can be welded conventionally only with great effort and energy input interest in alternative joining techniques is growing, such as solid state joining processes. In this work, the effect of refill friction stir spot welding (refill FSSW) on the crack propagation behavior in AA6082-T6 is studied. To be able to identify the individual fracture mechanism, refill FSSW was performed as a blind weld, i.e. only in one sheet designed as C(T)100 specimens. The vertical distance between notch and spot weld was varied and tested in two phases. First, a cyclic pre-crack was induced and then the specimen was caused to fail in quasi-static conditions, resulting in two different fracture modes. The results showed that the cyclic crack is dominated by residual stresses but the microstructure mainly influences the quasi-static crack propagation. It was also found that a stress concentration occurs in the transition area even without a hook. Furthermore, it was found that the crack propagation is not exclusively driven by the local strength but also by the angle at which the crack hits the spot weld.

KW - Engineering

KW - Refill friction stir spot welding

KW - Residual stress

KW - Crack propagation

KW - Fracture behavior

KW - Failure AA6082-T6

UR - http://www.scopus.com/inward/record.url?scp=85186266290&partnerID=8YFLogxK

U2 - 10.1016/j.engfracmech.2024.109963

DO - 10.1016/j.engfracmech.2024.109963

M3 - Journal articles

VL - 300

JO - Engineering Fracture Mechanics

JF - Engineering Fracture Mechanics

SN - 0013-7944

M1 - 109963

ER -