contamination

[fabio manno]

is written that when you tig , in this case chrome moly, and you touch tung in the molten puddle ,or the filler rod goes out of the shilding gas( argon), or you don`t use a dedicate wheel when you grind the tung, or your pre and post flow is not apprppriate, contaminations occur. what consequence you are going to have in your weldings even if they show nice and well done?

[arc]

the structure of the weld under the surface most likely will be compromised. IE porosity or other faults.

[Aerometalworker]

well many things could happen,
touching a tungsten to the molten pool can cause a splinter of tungsten to remain in the weld pool, this creates a brittle spot for a fatigue crack. Oxidation can cause inclusions of many different materials, also leading to fatigue cracks. Remember, 4130 ( if thats what your using ) is more sensitive to fatigue then mild steel. So to answer your question, the consequence is joint failure...that simple. Its up to you to decide if its ok if the joint fails.

[arc]

yeah what Aerometalworker said is all true was in a hurry and had no time to write it all out.

[FM117]

Aerometalworker also left out the almost instant consequence of a
tungsten touch..................
violent cursing followed by the urge to beat something, usually
the side of your own head for being %&#@ dumb!
Dave P.

[fabio manno]

thanks a lot to everybody