The Effect of Heat Input on the Defect Phases in High Frequency Electric Resistance Welding

다국어 초록 (Multilingual Abstract)

The effect of the chemical compositions of base material and ERW conditions on defect formation is studied
by an analysis of defect formation mechanism and defect phases in variation to heat input and apex angle.
In the high heat input range, a comet shape narrow gap is formed due to higher current density and higher
Lorentz force at the welding point than at the apex point. The comet shape narrow gap, which has a wider
width at the welding point, causes a penetrator rate increase by leading the retardation of sweeping speed
of molten metal bridge that discharges the oxides from the narrow gap. The increase of apex angle is very
effective in minimize the penetrator defect rate with the optimization of heat input. The oxides in cold weld
at low heat input range have an FeO phase, and the oxides in penetrator at high heat input range have an
Fe3O4 phase. The reason for the Fe3O4 phase in the penetrators is that the molten metal can be oxidized
first on the strip edges, and then the oxidation increase after being discharged from the narrow gap and
are refilled into the narrow gap due to the retardation of sweeping speed. Therefore, penetrators have Fe3O4-
MnO2 rather than FeO-MnO-SiO2 phases as proposed in previous articles. Mn amount contained in the base
material gives a more effective role to the penetrator defect rate than to the Mn/Si ratio.

다국어 초록 (Multilingual Abstract)

The effect of the chemical compositions of base material and ERW conditions on defect formation is studied
by an analysis of defect formation mechanism and defect phases in variation to heat input and apex angle.
In the high heat input range, a comet shape narrow gap is formed due to higher current density and higher
Lorentz force at the welding point than at the apex point. The comet shape narrow gap, which has a wider
width at the welding point, causes a penetrator rate increase by leading the retardation of sweeping speed
of molten metal bridge that discharges the oxides from the narrow gap. The increase of apex angle is very
effective in minimize the penetrator defect rate with the optimization of heat input. The oxides in cold weld
at low heat input range have an FeO phase, and the oxides in penetrator at high heat input range have an
Fe3O4 phase. The reason for the Fe3O4 phase in the penetrators is that the molten metal can be oxidized
first on the strip edges, and then the oxidation increase after being discharged from the narrow gap and
are refilled into the narrow gap due to the retardation of sweeping speed. Therefore, penetrators have Fe3O4-
MnO2 rather than FeO-MnO-SiO2 phases as proposed in previous articles. Mn amount contained in the base
material gives a more effective role to the penetrator defect rate than to the Mn/Si ratio.

참고문헌 (Reference)

1 N. Watanabe, 26 : 453-, 1986

2 T. Kyogoku, 35 : 61-, 1987

3 H. Haga, 59 : 208s-, 1980

4 M. Saito, 26 : 461-, 1986

5 J. H. Choi, 1-8, 1999

6 J. H. Choi, 85 : 27s-, 2004

7 C. M. Kim, 209 : 838-, 2009

8 H. Haga, 60 : 104s-, 1981