Burn-Through
Burn-through is the failed penetration of the base material at the root due to excessive heat input, leading to large holes.
Physical-Chemical Mechanism of Action
Excessive energy input into the weld zone causes uncontrolled burning of the steel at the root. This leads to the metal not completely vaporizing and instead transitioning into a molten state.
Metallurgical Relevance & Welding Risks
Burn-through can result in large holes or cracks at the root of the weld. This compromises the mechanical strength and toughness of the component, increases the risk of hot cracking, and can lead to failure under load.
Workshop Practice & Action Instructions
To avoid burn-through, ensure controlled heat input. Use a suitable backing material or a shielded welding technique. Keep the weld as short as possible and cool it carefully. If burn-through is suspected, fine machining or even re-welding may be required.