Resistance spot welding macro characteristics of the dissimilar thickness dual phase steels

• This paper describes the macro characteristics of the RSW joints.
• The melting rate of the DP600 side is always higher than DP780 side.
• The indentation rate of the D780 side is always higher than DP600 side.
• The DP780/DP600 welded joints get a larger nugget diameter than DP600/DP780.

In the present work, macro characteristics of the dissimilar thickness dual phase steel resistance spot welding joints were described in terms of melting rate, indentation rate, nugget diameter and indentation diameter. The results revealed that the melting rate of the DP600 side was higher than that of the DP780 side and the indentation rate of the DP600 side was lower than that of the DP780 side of the welded joints. The base metal lap order had the important effect on nugget diameter, and the DP780/DP600 spot welded joints tended to get the larger nugget diameter than DP600/DP780 spot welded joints with the same process parameters. The indentation diameters of DP600 and DP780 sides depended on the electrode geometry and force.