PSI - Issue 17

Available online at www.sciencedirect.com Structural I tegrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 17 (2019) 456–463

ICSI 2019 The 3rd International Conference on Structural Integrity Experimental and finite element analysis of progressive failure in ICSI 2019 The 3rd International Conference on Structural Integrity Experimental and finite element analysis of progressive failure in

friction stir welded AA6061-AA7075 joints Ashu Garg a, *, Madhav Raturi a , Anirban Bhattacharya a a Mechanical Engineering Department, Indian Institute of Technology Patna, Bihta, 801103, India friction stir welded AA6061-AA7075 joints Ashu Garg a, *, Madhav Raturi a , Anirban Bhattacharya a a Mechanical Engineering Department, Indian Institute of Technology Patna, Bihta, 801103, India

Abstract Abstract

In the present study, an in-situ analysis of crack initiation and propagation during tensile loading was captured using high speed camera for dissimilar friction stir weld joint of AA6061-T6 and AA7075-T651 prepared with plain cylindrical (CYL) and threaded with three intermittent flat faces (TIF) tool pins. To study notch sensitivity, experiment was also carried out for notch tensile sample creating notch at weld center. Joint failures were further predicted by finite element (FE) method. Results indicate that for joints obtained with CYL tool pin, crack initiated from vicinity of tunnel region however, propagated through the boundary of stir zone (SZ) and thermo-mechanically affected zone. FE results also indicate that the stresses and strain were confined near tunnel region which act as crack initiation site. For joints obtained with TIF tool pin, no tunnel/ void was noticed in the SZ and the sample failed from the heat affected zone on the advancing side (AA6061-T6) of the joints. For notch tensile specimen, the specimen exhibited minimum elongation when compared with tensile specimen and notch strength ratio > 1 indicated that the joint was notch insensitive or in other words, notch strengthened. FE result indicated that the higher stresses were confined near the notch root from where crack initiated and propagated through the SZ. Fractographic analysis showed the presence of dimples, micro-voids with some shear failure marks for all joints indicating the ductile fracture. In the present tudy, an in-situ analysis of crack initiation and propagation during tensile loading was captured using high spee camera for dissimilar f iction stir weld joint of AA6061-T6 and AA7075-T651 pr pared with plain cylindrical (CYL) and hreaded with three intermittent flat faces (TIF) tool pin . To study notch sensitivity, exp ri ent was also carried o t for notch ensile sample creat g notc at weld center. Joint failures were further predicted by finite element (FE) method. Results indicat that for joint obtai ed with CYL to l pin, cra k initiated from vicinity of tunnel region however, p opagated through th b undary of s ir zone (SZ) and thermo-me ha c lly affected z ne. FE results also indicate that the stresses and train were confined ear tunnel r gion which act as cr ck initiation site. For joints obtained with TIF tool pin, no tunnel/ void was noticed in th SZ and the sampl failed from the heat affected z e on the adv ncing side (AA6061-T6) of the j ints. For notch tensile specimen, the specimen exhibited minimum elongation when compared with tensile specimen and notch strength ratio > 1 indicated that th joint was notch insensitive or in other words, notch strengt ened. FE result indicated that the higher stresses w r confined near the notch root from wh re crack initiated and propagated through the SZ. Fractographic analysis showed the presence of dimples, micro-voids with some shear failure marks for all joints indicating the ductile fracture.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

Keywords: Friction stir welding; Finite element analysis; Tool pin profiles; Strength; Progressive failure Keywords: Friction stir welding; Finite element analysis; Tool pin profiles; Strength; Progressive failure

1. Introduction 1. Introduction

Friction stir welding (FSW) process is being widely adopted for joining of lightweight materials like aluminum alloys and others. The process gained significant importance due to the capability of joining similar and dissimilar Friction stir welding (FSW) process is being widely adopted for joining of lightweight materials like aluminum alloys and others. The process gained significant importance due to the capability of joining similar and dissimilar

* Corresponding author. Tel.: +91-612-302-8082. E-mail address: ashu.pme16@iitp.ac.in * Correspon ing aut or. T l.: +91-612-302-8082. E-mail address: ashu.pme16@iitp.ac.in

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.060