Effect of Si content on Nugget Diameter of Electric Resistance Spot Welded Dual Phase Steel

Kong, Jong-Pan; Kang, GilMo; Han, Tae-Kyo; Chin, Kwang-Geun; Kang, Chung-Yun

JWJ > Volume 29(5); 2011 > Article

Journal of KWJS 2011 October;29(5) :99-105.
Published online November 22, 2011.

Effect of Si content on Nugget Diameter of Electric Resistance Spot Welded Dual Phase Steel

Jong-Pan Kong, GilMo Kang, Tae-Kyo Han, Kwang-Geun Chin, Chung-Yun Kang

Correspondence: Published online November 22, 2011

ABSTRACT

  In this study, effect of Si content on nugget diameter in electric resistance spot welded dual-phase(DP) steel was investigated. The cold rolled DP steels with different Si content (0.5, 1.0, 1.5, 2.0 wt.%) were used and thickness of those sheet was 1.2mm. With increasing Si content, nugget diameter was increased at the same welding current. This is attributed to increase of heat input result from high resistivity. Also, nugget diameter was increased with an increase in Si content for the same heat input. For this reason, the melting point of DP steel is lowered with an increase in the Si content. And solid DP steel can easily be transformed to a liquid phase because the low melting point. Finally, a prediction formula for the nugget diameter(N.D.) could be obtained in terms of heat input(Q) and melting point(M.P) as follows:
  N.D.(㎜) = 0.11Q(J) - 0.0031 M.P.(℃) + 0.32

Keywords: Electric resistance spot welding;Si content;Nugget diameter;Resistivity;Melting point;Yield strength