Welding defects

1. What is a welding defect? ​​Answer: A defect that does not meet the standard requirements during the welding process.

2. Why does a fusion weld have defects? Answer: Due to the influence of factors such as people, machines, materials, methods, and environments, defects inside and outside the weld include: weld size does not meet the requirements, arc pits, burn-through, undercuts, weld bumps, severe spatter, slag inclusions, pores, cracks, etc.

3. What is a pore? Answer: During the welding process, the gas in the molten pool metal fails to escape before the metal cools, and forms holes in the weld metal (inside or on the surface).

4. What is a crack? Answer: Under the combined action of welding stress and other brittle factors, the gaps formed in the weld metal and the heat-affected zone (inside or on the surface) are called cracks. a) Hot cracks - cracks that occur immediately at high temperatures after welding. b) Cold cracks - cracks that occur when the metal cools to room temperature after welding; or cracks that occur a few hours or days after welding are called delayed cracks.

5. What is undercut? Answer: Due to incorrect welding parameter selection or incorrect operation method, the groove or depression produced along the base material part of the weld toe (fusion line) is called undercut, which will cause local stress concentration.

6. What is incomplete penetration? Answer: During welding, the root of the joint is not completely melted through.

7. What is incomplete fusion? Answer: During fusion welding, the part between the weld and the base material or between the welds is not completely melted and combined.

8. Why should the hydrogen content in the weld bead be controlled? Answer: The three harmful gases of hydrogen, oxygen and nitrogen will cause great harm to the welded joint; especially "hydrogen", which will cause hydrogen pores, hydrogen white spots, hydrogen embrittlement, hydrogen-induced cracks (delayed cracks) and other hazards.

9. What is welding spatter? Answer: During fusion welding, the molten metal particles and slag fly around.

10. What is weld nodule? Answer: During the welding process, a metal nodule is formed when the molten metal flows onto the unmelted base material outside the weld.