Nitralloy issues
Nitralloy issues
(OP)
Having some issues welding A355 nitralloy. Overlay of Stellite 6 with a 600 Degree F preheat is causeing some major warpage in the 3 inch diameter rod that I am welding on. Is the 600 Degree F nessisary for this small of diameter? The rod its self ranges from 24" to 52" in length, and 1" to 3" in diamter. Any suggjestions?





RE: Nitralloy issues
The 600 deg F is not the problem, your distortion is from the Stellite 6 weld shrinkage stresses. You have asked this question before regarding welding; thread292-154891.
You might want to try another approach using an Inconel 82 butter layer over the A355 Nitralloy, using the same preheat. After the butter layer, go with the Stellite hardfacing. This may help.
RE: Nitralloy issues
RE: Nitralloy issues
RE: Nitralloy issues
Ok. Are you applying the preheat uniformly, and holding this temperature before welding? Yes, the bar(s) will grow in dimension (radially and axially) because of heat. The excessive distortion you mentioned could also be from residual stresses in the bar(s), prior to welding. Unfortunately, you relieve these residual stresses from heat (welding or preheat, it makes no difference).
What you need to do is to obtain this material in an annealed condition to avoid having the bar supplied with inherent residual stresses. The Inconel butter layer that I recommended will help to reduce residual stresses from the Stellite 6 overlay.
RE: Nitralloy issues
RE: Nitralloy issues
RE: Nitralloy issues
Yes, and in addition to GRoberts information, buttering is a weld overlay. The Inconel 82 is very ductile and will reduce weld shrinkage stresses of Stellite 6 by absorbing the stresses. This should help to reduce distortion and reduce problems with depositing Stellite 6. The more I think about this weld build-up of Nitralloy, the Inconel interface layer makes sense. Again, treat the Inconel/Stellite hardfacing as a two layer weld build-up or overlay, and qualify this two layer weld build-up welding procedure using ASME Section IX as a guide.