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Effect of Postweld Aging Treatment on Fatigue Behavior of Pulsed Current Welded AA7075 Aluminum Alloy Joints

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Abstract

This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints.

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Acknowledgements

The authors are grateful to the Department of Manufacturing Engineering, Annamalai University, Annamalainagar, Tamil Nadu, India for extending the facilities of Metal Joining Laboratory and Materials Testing Laboratory to carryout this investigation. The authors also wish to express their sincere thanks to Directorate of Extramural Research & Intellectual Property Rights, Defence Research & Development Organisation (DRDO), New Delhi for the financial support to carryout this investigation through sponsored project No. ERIP/ER/0203351/M/01/633. The first two authors are very grateful to the third author, Dr. G. Madhusudhana Reddy, Scientist-F, Defence Metallurgical Research Laboratory (DMRL), Hyderabad for his valuable suggestions, guidance and discussion.

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Authors and Affiliations

  1. Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, 608 002, Tamil Nadu, India

    V. Balasubramanian & V. Ravisankar

  2. Metal Joining Section, Defence Metallurgical Research Laboratory (DMRL), Kanchanbag (PO), Hyderabad, 560 058, India

    G. Madhusudhan Reddy

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  1. V. Balasubramanian
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  2. V. Ravisankar
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  3. G. Madhusudhan Reddy
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Correspondence to V. Balasubramanian.

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Balasubramanian, V., Ravisankar, V. & Madhusudhan Reddy, G. Effect of Postweld Aging Treatment on Fatigue Behavior of Pulsed Current Welded AA7075 Aluminum Alloy Joints. J. of Materi Eng and Perform 17, 224–233 (2008). https://doi.org/10.1007/s11665-007-9129-9

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  • DOI: https://doi.org/10.1007/s11665-007-9129-9

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