Resistance spot welding of two steel sheets is carried out in lap joint configuration by using a welding current of 3KA and a weld time of 0.2s. a molten weld nugget of volume 20mm3 is obtained. The effective contact esistance is 200μW. The material properties of steel are given as (i) latent heat of melting 1400 kJ/kg, (ii) density 8000 kg/m3, (iii) melting temp 15200C, (iv) specific heat 0.5J/kgC. The ambient temp is 20C.
Heat (in Joules) used for producing weld nugget will be (assuming 100% heat transfer efficiency
(a) 324 (b) 334
(c) 344 (d) 354
Heat (joules) dissipated to the base metal will be (neglecting all other heat losses)
(a) 10 (b) 16
(c) 22 (d) 3