关键词: 异种钢, 电阻点焊, 形核过程, 数值模拟, 多场耦合

Abstract: A finite element model was established for resistance spot welding of DC01 with a thickness of 1.0 mm, DP590 with thicknesses of 1.2 mm and 1.5 mm. The energy distribution and stress-strain during the spot welding processes were analyzed using the multi-field coupling of thermal field, electric field, and force field. The test results show that the numerical simulation results are in good agree with the test ones. The peak current density decreases with time, and the distribution area is different from that of the two-layer plates, with a significantly larger area of distribution in the upper and lower plates compared with the middle plate. The potential changes indicate that initial heat generation in spot welding is mainly through contact resistance, which later transforms into bulk resistance. The temperature distribution on dissimilar unequal-thickness plates is uneven, with nucleation preferentially occurs on the lower part of the middle plate and on the DP590/DP590 contact surfaces. After the formation of the nugget, the middle part is under compressive stress, while the base material zone is under tensile stress at the nugget zone. The maximum strain value exists at the DP590/DP590 location.

Key words: dissimilar steel, resistance spot welding, nucleation process, numerical simulation, multi-field coupling