Two metallic sheets, each of 2.0 mm thickness, are welded in a lap joint configuration by resistance spot welding at a welding current of 10 kA and welding time of 10 millisecond. A spherical fusion zone extending up to the full thickness of each sheet is formed and properties of the metallic sheets are given as: Ambient temperature = 293 K Melting temperature = 1793 K Density = 7000 kg/m Latent heat of fusion = 300 kJ/kg Specific heat = 800 J/kgK. Assume: (i) contact resistance along sheet-interface is 500 micro-ohm and along electrode-sheet interface is zero; (ii) no conductive heat loss through the bulk sheet materials; and (iii) the complete weld fusion zone is at the melting temperature. The melting efficiency (in%) of the process is

Two metallic sheets, each of 2.0 mm thickness, are welded in a lap joi

1.	Two metallic sheets, each of 2.0 mm thickness, are welded in a lap joint configuration by resistance spot welding at a welding current of 10 kA and welding time of 10 millisecond. A spherical fusion zone extending up to the full thickness of each sheet is formed and properties of the metallic sheets are given as: Ambient temperature = 293 K Melting temperature = 1793 K Density = 7000 kg/m Latent heat of fusion = 300 kJ/kg Specific heat = 800 J/kgK. Assume: (i) contact resistance along sheet-interface is 500 micro-ohm and along electrode-sheet interface is zero; (ii) no conductive heat loss through the bulk sheet materials; and (iii) the complete weld fusion zone is at the melting temperature. The melting efficiency (in%) of the process is
A.	50.37
B.	60.37
C.	70.37
D.	80.37
Answer» D. 80.37

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