Heat Input During Welding
The thermal energy supplied to the component per unit length, which directly controls the cooling time and microstructure in the weld region. Precise limitation prevents unacceptable embrittlement.
The heat input during welding determines how much energy you put into the part. It depends on this how the structure in the weld and the heat-affected zone will look later. If you put in too little energy, the material won't melt through properly and you'll get cold spots or lack of fusion. But if you put in too much, the part overheats, it distorts, and the structure becomes coarse. You have to choose the parameters so that the material melts cleanly without the heat spreading too much to the sides. You get the feel for it by watching the weld pool and the weld shape.