AWS Welding Inspection and Testing Certification Practice Test

What can contribute to underbead cracking?

1. Welding on clean metal

2. Welding on wet or contaminated metal

3. Welding with high-quality electrodes

4. Welding at high speeds

The correct answer is: Welding on clean metal

Underbead cracking is a type of weld defect that often occurs due to thermal stresses and the specific conditions under which the welding takes place. When welding on clean metal, the absence of contaminants such as moisture, oil, or rust means that there are fewer barriers to proper fusion. This ensures better metallurgical bonding between the weld metal and the base metal, reducing the likelihood of defects such as cracking. In contrast, conditions like welding on wet or contaminated metal can introduce hydrogen and other impurities into the weld pool, increasing the risk of cracking. High-quality electrodes are designed to improve weld quality but do not inherently prevent underbead cracking if other adverse conditions are present. Welding at high speeds may lead to insufficient heat input, which can also affect the quality of the weld and the integrity of the joint, potentially contributing to problems such as underbead cracking.