| Spot, weldability of the galvanized steel, galvanneld steel and cold rolled steel is compared exclusively in this study. In order to investigate the effects of welding parameters on the weld strength of each steel, welding current and welding time were systematically varied under a constant pressure. Spot weldability of surface coated steels was strongly dependent upon types of coating although the compositions of coating (Zn-Fe) and base plate were almost identical. As the welding heat input (current and time) increased, nugget size and strength increased. However, when heat input (especially current) was greater than a critical value, effects of energy input became minor. Results also demonstrate that the tensile shear strength can be expressed by a second order equation of welding current and welding time. Experimental data fall within 5% error limit of the calculated values. |
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