Root reinforcement height
The root reinforcement is the maximum allowable bulging of the weld metal on the root side in single-sided butt joints. Exceeding this limit leads to notch stresses and potential cracking.
Physicochemical Mechanism of Action
The root excess weld metal forms through the different expansion of the weld metal on both sides of the joint. With single-sided welded joints, the unwelded material (root) is pulled under tension, which leads to a bulge.
Metallurgical Relevance & Welding Risks
Too much root excess can lead to notch stresses in the unwelded material. These stresses can cause cracks, especially when the material is under mechanical load. The excess also hurts the weld fusion and can lead to missing connection pieces.
Workshop Practice & Instructions
The allowable root excess is in most cases 0.5 to 1 mm. With an excess over 1 mm, the weld should be checked and repaired if necessary. Make sure the unwelded material is not pulled too strongly and use appropriate weld throttling.