Mat Saad, Nurihal Hanim
(2012)
Effect Of Resistance Spot Welding Parameters On Copper And Brass.
Masters thesis, Universiti Sains Malaysia.
Abstract
Resistance spot welding is the most commonly used method for joining sheet metals. Most studies in this technique were focus on selected materials and little
information is available regarding the response and behaviour of copper and copper alloy. Thus, in this research is purposed to study the effect of resistance spot welding parameters on copper and brass alloy. The copper and brass welded by resistance spot welding technique under varied welding currents and applied loads has been investigated. A nugget measurement looked at the influence of loads (60 N, 65 N, 70 N and 75 N) and weld currents (5.50 kA, 6.00 kA and 6.50 kA) on both fusion area and internal porosity. Nugget diameter increased at low and high-level of welding current, but significantly restricted to a maximum value at intermediate level of
welding. Furthermore, copper joints revealed more oxide formation and crack development, while brass joints revealed some pores and excess penetration in the
fusion area. Thus, the weld currents were increased up to 8.00 kA, 8.50 kA and 8.90 kA, while applied load parameters were kept constant at 60 N, 65 N, 70 N and 75 N to which taken as optimised values to improve the weld joined. The mechanical properties and microstructure of these welded copper and brass was detailed. Specimens joined at higher welding current yielded higher tensile-shear strength results than those joined at lowest welding current. Failure modes are detailed by
observing weld fracture surfaces. A correlation between base metal and fusion zone hardness is produced. The hardness of brass joints gave the highest hardness values due to grains refinement resulted from the weld nugget zone and this was followed by HAZ and original base metal. While copper joints revealed the weld nugget by HAZ and original base metal. While copper joints revealed the weld nugget gives the lowest hardness values than the original base metal due to annealing softeningwas dominant caused coarsening grain structures.
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