Why are arc marks bad?

Since an arc strike is typically small and happens fast, the volume of the base material that received the arc strike will heat and cool rapidly. This can result in the formation of an extremely hard and brittle microstructure that could be prone to cracks.

What are some of the problems that might occur when high temperatures are used in welding?

Here are some of the most common problems that occur with welding and how to fix them.

1. Spatter. Spatter occurs when droplets of molten material are produced near welding arc.
2. Porosity.
3. Undercut.
4. Deformation.
5. Cracks.
6. Incomplete Penetration and Fusion.
7. Slag Inclusions.
8. Incorrect Wire Delivery.

What are the causes of welding defects?

Most defects encountered in welding are due to an improper welding procedure. Once the causes are determined, the operator can easily correct the problem. Defects usually encountered include incomplete penetration, incomplete fusion, undercutting, porosity, and longitudinal cracking.

Why do most welding failures occur in the heat affected zone explain?

The heat affected zone is an inevitable part of high-temperature metal cutting and welding procedures. The cause lies with overheating of the metal during these processes and it can affect the material properties.

What is heat affected zone What are its implications in arc welding process?

The heat affected zone (HAZ) is a non-melted area of metal that has undergone changes in material properties as a result of being exposed to high temperatures. These changes in material property are usually as a result of welding or high-heat cutting.

What causes arc strikes?

Arc strike This is a defect caused by instantaneously striking an arc on the base material. In other words, an arc strike is a spot of failed arc ignition which was not fused by subsequent welding and remained on the base material. Arc strike may be the cause of cracking in the base material.

What is defect in arc welding?

Welding Defects can be defined as the irregularities formed in the given weld metal due to wrong welding process or incorrect welding patterns, etc. The defect may differ from the desired weld bead shape, size, and intended quality. Welding defects may occur either outside or inside the weld metal.

What are the Arc welding defects?

What are common weld defects?

• Lack Of Penetration or Incomplete Penetration.
• Lack Of Fusion or Incomplete Fusion.
• Undercut.
• Spatter.
• Slag Inclusions.
• Cracks.
• Porosity.
• Overlap.

What are the various defects of arc welding?

11.2 Defects in arc welding

What is the problem with arc welding?

The problem comes about when the arc is established outside of the area to be welded and this strike leaves a very hard area (due to the momentary strike that creates a hard node) that with any stress can become the start point for a crack or small fracture that with continued stress will grow until complete failure of the part

Why is an arc strike considered a defect?

Arc strike is considered a defect because there is a localized area where the base metal has melted and then rapidly cooled ( similar to quenching ). this leads to the formation of a heat affected zone, albeit a small one.

What happens if you leave an arc strike on a pipeline?

If you left an arc strike on the water wall tubes they would burn through in less than a week in some areas of the near impingement zone. I was up on the Alaskan Pipeline in 1974, and the welders were only allowed to have two arc strikes in their lifetime, before being sent down to the lower forty eight.

How does an arc strike affect low carbon steel?

John Wright’s experiment as described in the Forum and by Brent’s article in Inspection Trends provides some useful insight on the damage an arc strike can do to the mechanical properties of low carbon steel. The arc strike does clearly cause metallurgical changes to the localized area defined as an arc strike.