Welding Heat Input Coefficient
The welding heat input coefficient indicates how much thermal energy is actually introduced into the component. It helps calculate cooling times and thermal cycles.
Physicochemical mechanism of action
The welding heat input coefficient (SEK) is the ratio of the thermal energy actually introduced into the workpiece to the electrical energy of the arc. It takes into account the efficiency of heat transfer and can range from 0.2 to 0.4.
Metallurgical relevance & risks during welding
A SEK that is too low leads to insufficient heating of the workpiece, which can result in incomplete fusion and lack of joint strength. A SEK that is too high increases the risk of overheating and subsequent rapid cooling, which can lead to crack-prone martensite and hot cracks.
Workshop practice & action instructions
To set the SEK optimally, monitor the temperature curve and the arc power. At a SEK of 0.3, a cooling time of 15 to 20 seconds per millimeter of steel thickness is recommended. Avoid severe overheating and ensure controlled cooling.