Welding Failure Analysis

The use of welding to create components and assemblies also creates situations where the weld junction is subjected to stresses that seek out the weld joint to initiate a failure. Welds are typically designed with the intended stresses in mind. Additional complicating factors can be cyclic stresses, corrosion and weld quality that can all concentrate on the weld to initiate a weld failure. Stress concentration factors can also magnify the stresses at a weld joint to imitate a weld failure.

Mr. Metal has had experience with countless weld related failures both large and small. If a weld joint appears fractured within an assembly it is important to identify the order of an assembly failure. Was the welding the site of an instantaneous failure after another component failed and then the stresses increased on the weld to cause the secondary fracture. Was corrosion present that should not have been there due to water treatment. Stainless steel weld joins are not corrosion proof depending on the environment and the use of proper base material. When performing a weld failure analysis the background and history is important to possibly identify what may have been incorrectly or overlooked when the weld joint was designed.

If any corrosion residue is present the residue should be evaluated by energy dispersive techniques to possible Identify the elements back to the source of the corrosion. That helps track the weld failure to a possible corrosion component that may be combining with the stresses acting on the weld to cause the failure. Weld junctions are always suspect within a failure analysis scenario and the quality of the weld junction to the applicable welding code requirements must be confirmed as part of the investigation. All of the required weld tests are performed with the other metallurgical failure analysis tests and examinations to identify root cause and provide recommendations for prevention of future weld failures. BUT, welds are suspect and the quality of the junction to code requirements must be verified before moving on to continue searching for root cause of the welding failure analysis.