Arc strikes and surface damage
Arc strikes and arc blow are localized damages on the material surface caused by unintentional arc striking during welding. They lead to hardening and increased crack risk.
Physical-Chemical Working Mechanism
Arc strikes occur when the arc light unintentionally hits the material surface. This leads to localized hardening of the material due to rapid cooling and the formation of a glass-hard structure like martensite.
Metallurgical Relevance & Welding Risks
Arc strikes can lead to localized cracks and distortion, especially if they are close to the weld. The hardening makes the material very hard at that spot and sensitive to mechanical stress.
Shop Practice & Action Steps
Use a suitable protective coating on the material surface to avoid arc strikes. Make sure the arc is correctly aligned and shielded. If you find arc strikes, gently grind the affected area and, if necessary, apply an additional weld pass.