| Title |
Effect of Heat Input Variation in High-Frequency Electric Resistance Welding on Hydrogen-Induced
Cracking and Oscillation Frequency Characteristics of API X70 Steel |
| Authors |
하정우(Jung-Woo Ha) ; 김성웅(Sung-woong Kim) ; 정민찬(Min-Chan Jung) ; 손호상(Ho-Sang Sohn) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.1.27 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Hydrogen embrittlement; Narrow gap; Oscillation frequency; Strength of heat input; Welding inclusions |
| Abstract |
This study investigates a methodology for quantitatively assessing the welding phenomenon during
High-Frequency Electric Resistance Welding (HF-ERW) to achieve stable resistance against Hydrogen
Embrittlement (HE). This assessment is performed by analyzing variations in oscillation frequency. The
occurrence of Hydrogen-Induced Cracking (HIC) was observed to depend on variations in heat input, with
cracks primarily initiating and propagating from welding inclusions (penetrator) distributed along the
ND(Normal Direction) within the bondline. The residual presence of these inclusions is fundamentally
determined by the formation of the narrow gap and migration of the bridge, which are themselves dictated
by changes in the welding phenomenon. Since the dynamic evolution of the narrow gap and bridge directly
causes fluctuations in the current path, these path changes were quantitatively detected by monitoring
variations in the oscillation frequency. From these frequency variations, a key metric termed ‘‘Strength of
Heat Input’’?representing the heat input applied to the material during one cycle of bridge movement?was
extracted. The stability of the welding process can be reliably assessed by monitoring the deviation of the
Strength of Heat Input over a unit of time. A large deviation under the constant welding conditions signifies
irregular formation and migration of the bridge. This irregularity subsequently increases the probability of
residual welding inclusions (penetrator), that severely reduce resistance to hydrogen embrittlement. This
research contributes to enhancing the hydrogen embrittlement resistance of HF-ERW by establishing a
quantitative framework for assessing and maintaining stable welding phenomena. |