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|Title:||EFFECT OF PULSED CURRENT PARAMETERS ON WELD CHARACTERISTICS IN MIG WELDING|
|Authors:||Jain, Naveen Kumar|
|Keywords:||MECHANICAL & INDUSTRIAL ENGINEERING;PULSED CURRENT;WELDED;MIG WELDING|
|Abstract:||The effect of pulse frequency at the two different levels of mean current on the mechanical properties of the weld metal, in an Al-Zn-Mg alloy (Zn 4.0-5.0%, Mg 1.0-1,5%,, Mn 0.2-0.7%, Fe 0.7% max, Cu 0.2% max, others 0.15% and rest aluminium) have been studied using the pulsed arc MIG welding process. Two 1.6 mm 0 filler wire, o of 9~ composition Al-4.5% Pig (5183) and ter an indegeneous made wtL I?M filler (Mg 4 5-5.5/0, Fe 01,5/0, Mn , 0.5%, Si 0.3%, Cr 0.25%, Zn 0.2%, Ti 0.2%, Cu 0.1/ and rest alumi-nium) have been used in this investigation for making the welds. The pulse frequency has been varied at 25, 50 and 100 cycles/sec. Using the same filler wire the welding of the above mentioned alloy has also been carried out at 0 cycles/sec (equivalent to conventional IvJG) , for the two different levels of mean current. The microstructural features of the weld metal re-suiting from the various pulse frequencies have been studied under optical and scanning electron microscope and compared with the conventional, oz e. A some what better morphology of the weld metal, in respect to *the refinement in cast structure, has been marked in weld-merits produced by pulsed current welding process in comparison. to the conventional one. However, maximum refinement is found in the cast structure at some critical level of frequency in either case of mean current. The mechanical properties such as the hardness and notch ductility of weld metal have been estimated and found better in the welds made under current pulsation mode as compared to that of the conventional one. Further it has been noted that welds made at 50 cycles/sec gives a signi-ficant improvement in the notch ductility of weld metal over the other frequency levels. No improvement is obser-ved in notch. tensile strength of weld metal in the welds made at various pulse frequencies. Hcwever, notch ducti-lity and notch tensile strength are not the true picture of mechanical properties of the weld because a significant amount of porosity is observed in case of welds made at various pulse frequencies.|
|Research Supervisor/ Guide:||Ghosh, P. K.|
Gupta, P. C.
|Appears in Collections:||MASTERS' DISSERTATIONS (MIED)|
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