when a welding stainless steels. A welder holds the shielding gas over the end of the weld from his gtaw rig, after pulling out of his arc and while the weld is still red hot does this create a martinsitic area?
A welder holds the shielding gas over the end of the weld from his gtaw rig, after pulling out of his arc and while the weld is still red hot does this create a martinsitic area?
the stainless steel can be 308 309 316 304 any common welding grade. conditions are as in pipe welded in the field with I.D. purge. Can you tell me if it would change the ferritic number. Would this be measurable on a severn gauge?
No, there is no change. The ferrite number is based on chemical composition of the weld deposit itself and dilution effects from the base metal along the fusion zone of the weld.
It is good practice to reduce oxidation to keep your gas coverage over the weld for several seconds after the arc is extenguished on stainless steel. This will not cause any metallurgical problems on any type of stainless steel or other metal since the dominant mode of heat removal in welding is always conduction of the heat to the surrounding base meatal.