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Ratna Kumar, K.
- Studies on Partially Melted Zone and Pitting Corrosion Resistance of A356 Aluminium-Silicon Alloy GTA Welds
Authors
1 Department of Metallurgical Engineering, Government Polytechnic, Visakhapatnam-530 007, IN
2 Metal Joining Group, Defence Metallurgical Research Laboratory, Hyderabad-500 058, IN
3 Department of Metallurgical Engineering, Andhra University College of Engineering(A), Visakhapatnam-530 003, IN
Source
Indian Welding Journal, Vol 47, No 1 (2014), Pagination: 27-42Abstract
Gas Tungsten Arc Welding (GTAW) of Pressure Die cast A356 Al-Si alloy with strontium modification was done both with and without filler. The microstructural changes in Weld metal zone (WM), Heat affected zone (HAZ) and Partially Melted Zone (PMZ) were studied. PMZ of aluminium alloy weld is an important region, as it is the weak link in the weldments. It is significantly affected by the welding parameters, filler metal and prior thermal condition. In the present work affect of welding techniques i.e. Continuous Current Gas Tungsten Arc Welding (CCGTAW) and pulsed Current Gas Tungsten Arc Welding (PCGTAW) on microstructure and pitting corrosion resistance of weld metal, Partially melted zone and Heat affected zone in the prior conditions of as cast and T6 conditions were studied. Susceptibility to liquation was found to be less in the weld made in as cast condition of pulsed current GTA welds compared to that of artificially aged condition (T6) of continuous current GTA welds. This was mainly attributed to the silicon enrichment of eutectics at the grain boundaries. Potentiodynamic polarization testing was carried out to study the pitting corrosion behavior of the welds. Pitting corrosion resistance of weld made with pulsed current GTAW of as cast alloy is better than the that of weld made with continuous current GTAW of T6 alloy. This is mainly attributed to the discontinuous eutectic formation at the grain boundary base metal and PMZ.Keywords
Aluminium Alloys, GTA Welds, Partially Melted Zone, Continuous Current Gas Tungsten Arc Welding, Pulsed Current Gas Tungsten Arc Welding.
- Effect of Welding Process on Microstructure and Pitting Corrosion Behavior of AA2014 Al-Cu Alloy Welds
Authors
1 Department of Mechanical Engineering, GITAM Institute of Technology, GITAM University, Visakhapatnam - 530045, IN
2 Department of Metallurgical Engineering, Government Polytechnic, Visakhapatnam - 530 007, IN
3 Metal Joining Group, Defence Metallurgical Research Laboratory, Hyderabad - 500 058, IN
4 Department of Metallurgical Engineering, Andhra University College of Engineering (A), Visakhapatnam- 530 003, IN
Source
Indian Welding Journal, Vol 45, No 3 (2012), Pagination: 29-40Abstract
Wrought AA 2014 Al-Cu alloy in mill annealed (O) condition and naturally aged (T4) condition was welded by the Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW) processes. The microstructural changes and pitting corrosion behaviour in all zones of welds for both the welding processes have been investigated when the alloy was welded in O as well as in T4 conditions. It was observed that naturally aged (T4) alloy weld exhibited better corrosion properties than annealed (O) alloy weld this is attributed to the precipitation of fine grained eutectics in T4 alloy during welding. The pitting corrosion resistance was found to be better and uniform through out cross section of the friction stir welds compared to GTA welds, indicating improvement in corrosion properties of the welds in solid state welding.Keywords
Gas Tungsten Arc Welding, Friction Stir Welding, AA2014 Alloy, Partially Melted Zone, Thermomechanically Affected Zone, Pitting Corrosion, Potentiodynamic Polarization.- Partially Melted Zone in Dissimilar Aluminium Alloy Welds-Effect of Prior Thermal Temper and Welding Process
Authors
1 Department of Mechanical Engg., PVP Siddhartha Institute of Technology, Vijayawada-520007, IN
2 Defence Metallurgical Research Laboratory, Hyderabad-500 058, IN
3 Department of Metallurgical Engineering, Andhra University College of Engineering(A), Visakhapatnam - 530 003, IN
Source
Indian Welding Journal, Vol 43, No 2 (2010), Pagination: 32-40Abstract
Partially melted zone (PMZ) of aluminium alloy welds is an important region and requires careful attention. This is mainly because PMZ in these alloys is a weak link in the weldments and is significantly affected by welding parameters. Microstructural changes in PMZ are related not only to welding heat input and processes, but also depend on the initial thermal history of the alloy (for example, whether it is in O, T4, T6 orT87 condition etc.). Interestingly not many detailed studies are available in this respect. In the present work effect of prior thermal temper and welding process on the PMZ behaviour of dissimilar AA2014 and AA6061 alloy GTA and EB welds were studied. Grain coarsening and melting in PMZ is more when the alloys are welded in T4 temper than in O condition and AA2014 alloy is prone for liquation compared to AA6061 alloy which attributes high alloying element concentration in AA2014 side of the joint. EB welding proved to be efficient welding process compared to GTA welding in terms of resistance to liquation and better mechanical properties.