Root crack
A root crack is a crack near the weld root, hard to detect. Causes are high shrinkage stresses, poor fit-up, or hydrogen influence. It can degrade the mechanical properties.
Physical-Chemical Mechanism of Action
A root crack is caused by high shrinkage stresses, poor fit-up, or hydrogen influence. During cooling, the metal shrinks and creates stresses that can lead to cracks. If hydrogen concentrates in the weld zone, it can reduce material strength and promote cracking.
Metallurgical Relevance & Welding Risks
A root crack can degrade mechanical properties, especially in stress fields. It can lead to fractures or cracks under load and reduce the component's service life. In severe cases, the entire component may be at risk.
Workshop Practice & Action Guidelines
To avoid root cracks, ensure good fit-up of the weld joint and use appropriate hydrogen control measures. Control the cooling process and avoid rapid or uneven cooling. If suspected, perform a thorough inspection, e.g., using ultrasonic testing.