Welding temperature is primarily influenced by the high-frequency eddy current thermal power. According to formula (2), the high-frequency eddy current thermal power is mainly affected by the current frequency, and the thermal power of eddy currents is proportional to the square of the current frequency. Moreover, the current frequency is influenced by the激励电压, current, capacitance, and inductance. The formula for the激励 frequency is: f = 1/[2π√(CL)] ...(1) Where: f - 激励 frequency (Hz); C - capacitance in the激励 circuit (F), capacitance = charge/voltage; L - inductance in the激励 circuit, inductance = flux/current.

The formula indicates that the激励频率 is inversely proportional to the square root of the capacitance and inductance in the激励 loop, or directly proportional to the square root of the voltage and current. Simply altering the capacitance, inductance, voltage, or current in the loop can change the激励 frequency, thereby controlling the welding temperature. For low-carbon steel, a welding temperature of 1250~1460°C is sufficient to meet the penetration requirements for pipe walls with a thickness of 3~5mm. Additionally, the welding temperature can also be adjusted by modifying the welding speed.

When input heat is insufficient, the heated weld edge fails to reach the welding temperature, the metal remains solid, forming incomplete fusion or lack of penetration; when input heat is excessive, the heated weld edge exceeds the welding temperature, causing overheating or molten droplets, creating melt-through in the weld.