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International Journal of Material and Mechanical Engineering
Number of Followers: 24  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2162-0695 - ISSN (Online) 2164-280X
Published by Science and Eng Pub Co. Homepage  [45 journals]
  • Effect of Composite Back up Bar on Mechanical Properties of GTAW Weldments
           of AA 6061 –T6 Aluminium Alloy

    • Abstract: Effect of Composite Back up Bar on Mechanical Properties of GTAW Weldments of AA 6061 –T6 Aluminium Alloy
      Pages 1-8
      Author Hemadri Naidu TChannakeshavalu
      AA 6061- T6 Aluminium alloy is medium high strength heat treatable wrought Aluminium alloy belonging to Al-Mg-Si family and used for both strategic as well as structural applications. Its good general corrosion resistance coupled with good workability made AA 6061 a work horse alloy among weldable aluminium alloys. AA 6061 weldments with ER 4043 filler wire invariably fail in heat affected zone (HAZ) due to dissolution of metastable Mg2Si strengthening phases due to induced weld thermal energy. The process of dissolution of metastable Mg2Si phases can be retarded by balance thermal management during welding. In the present study, the thermal management followed is employing a composite back up bar with SS at the center and copper segments at the lips to facilitate slow heat extraction in the weld such that slower cooling rates in the weld avoid solidification cracking, and fast cooling of HAZ regions due to copper lips to mitigate the rate of dissolution of Mg2Si strengthening phases. This fast heat extraction from HAZ regions is further improved upon by using low heat input current pulsed AC TIG welding process in place of conventional AC TIG welding process. This technical paper delineates the welding process and parameters adopted by juxtaposing the composite back up bar and the resultant joint strength. Over 20% improvement in weld mechanical properties compared to conventional back-up bar observed. The present study established that effective method of heat extraction from the HAZ region by employing composite back-up bar and method inturn improved weldments properties without impairing the fabrication weldability.
      PubDate: 2017-02
School of Mathematical and Computer Sciences
Heriot-Watt University
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