Types of Welding Defects That Automated Optical Inspection Equipment Can Inspect

There are many types of welding defects, and automated optical inspection equipment was born to deal with various welding defects. So, what are the types of welding defects? Let's talk about the types of welding defects below.

Welding defect refers to the defects formed in the welding process of the welding joint. Welding defects include pores, slag inclusions, incomplete penetration, lack of fusion, cracks, pits, undercuts, weld bumps, etc. Among these defects, pores and slag inclusions (dots) are volume defects. Slag, lack of penetration, lack of fusion and cracks are linear defects and can also be called surface defects. In particular, cracks and lack of fusion are surface defects. Pits, undercuts, weld bumps and surface cracks are surface defects. Other defects (including internal buried cracks) are all buried defects.

1. Appearance defects
The appearance defect refers to the defect that can be found from the surface of the workpiece without the aid of an instrument. Common appearance defects include undercuts, weld bumps, depressions and welding deformations, and sometimes surface pores and surface cracks. The root of single-sided welding is not penetrated, etc.

2. Welding tumor
The liquid metal in the weld flows to the unmelted base material under heating or overflows from the root of the weld, and the metal nodules formed after cooling that are not fused with the base metal are weld nodules. Excessive welding specifications, too fast welding rod melting, poor welding rod quality (e.g. eccentricity), unstable welding power source characteristics and improper operating posture are all likely to cause welding defects. It is easier to form weld bead in the horizontal, vertical and upward positions.

3. Pit
The pit refers to the part of the surface or back of the weld that is lower than the base material. The pits are mostly caused by the welding rods not staying for a short time when the arc is closed, and the roots of the back of the weld are often concave. The pit reduces the effective cross-sectional area of the weld, and the crater often has crater cracks and crater shrinkage holes.

4. Not fully welded
Under-welded refers to continuous or intermittent grooves on the surface of the weld. Insufficient filler metal is the root cause of insufficient welding. The specification is too weak, the welding rod is too thin, improper handling, etc. will lead to under welding.