Welding defects

[GemmellG]

Conducted test samples welding over used stainless steel clad material using Machine GMAW+P. (ERNiCrMo-3 0.045” 100% Argon). Purpose of test is to verify the importance of surface prep & the importance of removal of known defects.

Test material was grit blasted to an industrial finish, no other surface prep was done. Please note there were indications in the weld zone such as fatigue cracking, elephant-hyde. Test coupon chemical analysis showed sulfur compounds and hydrocarbons in the scales inside the existing cracks. Welding parameters used to qualify the procedure was used for the test sample. Test results showed a very prominent individual beads, with an irregular and prominent profile, deep depressions between adjacent weld passes, also lack of fusion between beads. There was also a black surface oxide scale, out of qualification overlapping.

The above mentioned defects are related to the welding parameters i.e. volts, amps, travel speed, & shielding gas. As mentioned above the welding parameters used for the procedure qualification was used for the sample is the state of cleanliness the main factor for the parameters to go out of sync i.s scale ect.

 

[metengr]

The presence of sulfur in the thermal fatigue cracks (my guess based on weld overlays I have seen with carrot top profiles, are notorious for entrapment of contaminants. These contaminants are introduced into the weld puddle resulting in weld defects, including hot short cracks, lack of fusion and porosity. This is why welding over artifacts or cracks is not recommended.