Abstract
A systematic study was performed on two types of welding circuit with different inductances and one welding coil at five discharge energies for each circuit. The inductance of each circuit was determined by adding its respective remaining inductance and one effective inductance. This study demonstrated a condition necessary for fabricating an A6061-T6/DP590 welded sheet, resulting in a high deformation velocity of an A6061-T6 moving sheet and a large impulse generated on the sheet after the first collision. The three elements of a discharge current are the maximum value, oscillating period and damping coefficient. Compared with the maximum value, the time to the maximum value and the period in the measured discharge currents, the corresponding error rates of discharge currents reproduced by calculation are very low. Therefore, both the magnetic pressure and the impulse calculated from the reproduced discharge currents are highly reliable. The condition affecting the joining strength of the welded sheet was verified from the collision velocity and the impulse. It was clarified that the high collision velocity above 300 m∙s-1 and the large impulse from the first collision to approximately 14 μs resulted in the fabrication of the welded sheet with high welding strength.
