Common Defects In Welding

We have seen the overview of a welding process, Arc welding process, Gas welding process,  types of flames in Gas welding and Difference between Arc welding and Gas welding, difference between DC  welding and AC welding and soldering and brazing with the help of our previous posts.

Let us see now the type of welding defects in a welding procedure.

Welding Defects

Welding defects could be considered as flaws or deviations that compromises the quality and usefulness of welding.

Welding might have the following mentioned defects 

1. Porosity 

2. Cracks 

3. Lack of fusion 

4. Over penetration 

5. Slag inclusion

6. Burn-through

Porosity 

Porosity is basically a type of welding defect which is caused by the presence of gasses released in the welding process entrapped during the solidification. 

Cracks 

Welding cracks are basically two types i.e. cold cracks and hot cracks. Hot cracks occur at elevated temperature just after the molten metal starts to solidify. 

Cold cracks occur when three situations are available i.e. sufficient level of hydrogen, enough sensitive material involved and a high level of residual stress. 

Lack of fusion 

This type of welding defect is basically due to insufficient temperature rise of the base metal, failure to remove oxide films. 

Overpenetration

This type of welding defect is due to excessive current in arc welding. 

Slag inclusions 

Slag is formed by the reaction with fluxes and floats on the top of the weld pool. Due to the arc

force, the slag goes into the weld pool and solidifies inside the fusion zone and forms slag inclusion.

Slag inclusion defects are formed basically due to the factors such as inconsistent travel speed, incorrect electrode angle, incorrect size of electrode, not removal of slag during welding procedure etc. 

Burn-through

Burn-through, also known as undesirable open hole in welding, a type of welding defect where a hole has been completely melted through the base metal due to excessive heat input.

We will see the "What are the safety precautions used in welding and its personal protective equipment ?" in our next post.

Reference

Engineering Practices by Mr. S. SUYAMBAZHAHAN