Welding 17-4ph stainless steel 2

[CBF]

I would like to know when tig welding 17-4ph stainless steel material, what procedure and filler wire wire should be used. The material is 1/4" x 1/4" square bar that needs to be cut and butt welded and must remain perfectly straight.

 

[metengr]

CBF;
Prior to providing guidance on a welding information and filler metal, there are several questions. What is the heat treatment condition of the 17-4 PH bar prior to butt welding? Will the bar be used in a heat treated condition after welding to achieve a specified strength requirement for your application?

 

[CBF]

I do not know the hardness of the piece. It is a guide a doctor uses for doing knee replacements. As it is now it is to long and he wants it shortened. I really do not see any big stresses on this guide when it is being used. The guide is manufactured by a major medical supply co. and I do not think they will give me that information. Any information would be a great help. It is probably smart to just walk away from this job, but my curiousity has got me!

 

[metengr]

CBF;
Considering the situation, it would be a smart thing to walk away from this job. This sounds like "reverse engineering", which requires you to have ALL information pertaining to material and heat treatment condition. Attempting to fabricate (weld) a smaller guide would be pure guess work without proper design information, and could result in serious consequences.

17-4 PH is readily weldable with the GTAW (TIG) or SMAW (stick) processes using minimal preheat and maintaining the interpass temperature at or below 250 deg F during welding. You have several choices for weld filler metal - an AWS ER630 (17Cr-4Ni composition), Inconel 82 (nickel base) or an ER308L. This is the reason why you need to know the heat treatment condition specified for this guide.

 

[jomor]

CBF,

It has been my experience that you would probably have to post weld machining to keep the bar perfectly strait. If you have the ability to machine it you may want to use a different means of fastening that may allow adjustability. Or possibly a low temp brazing to minimize the local heating.

jomor