Weld Defect #1: Lack of Fusion

Running the Weld Test Centre here for the past 6 years, we have heard every excuse in the book for why a weld fails and I am considering a blog post listing the most interesting reasons we get.  Many welders want to see their weld and understand why it has failed.  Respecting that this is their livelihood we want to help them understand the failures that occur after many of the same questions, one of the women in the office set out to do some research.  She has found some great information on some of the most common weld defects.  So here we are, a series of three blogs on the top three weld defects that we see, here at our weld test centre.

Weld Defects – Week 1 – Lack of Fusion

In our experience Lack of Fusion is the single most common reason for failure. What exactly is Lack of Fusion?

Definition of FUSION: The melting together of filler metal and the base metal.  – Thank you to “Welding skills by R.T. Miller, 2nd edition, published 1997.

Weld DefectsLack of Fusion before bending and after on a CWB Test Plate

Incomplete Fusion (Lack of Fusion) – Discontinuance of a weld where fusion does not occur between the weld metal and fusion faces of the joint. (nk you to “Welding skills by R.T. Miller, 2nd edition, published 1997.)

In order to ensure that the new piece is as strong as a single piece of material, the weld metal must adequately be fused to the parent metal.

There is lots of really technical writing out there about Lack of Fusion, its causes, and ways to prevent this defect.   The best article we have found is by ESAB http://www.esabna.com/euweb/mig_handbook/592mig10_3.htm

Stay tuned next week for Weld Defect #2 –  Incomplete Penetration.

Until then,

Bonnie Pankratz