455 S.S. tube rusting after welding
455 S.S. tube rusting after welding
(OP)
I am welding a handle made from 17-4 S.S. to a machined tube made from 455 S.S., parts are joined together via GTAW with 17-4 S.S. filler , units are cleaned heat treated and passavated , the completed part is a Orthopedic Surgery Tool, problem is that we are getting rust on the 455 tube bore , mostly in the welded area , any thoughts would be appreciated.
Phil L.
Phil L.





RE: 455 S.S. tube rusting after welding
Are you sure it is rust and not heat tint?
What is the heat treatment aging temperature?
RE: 455 S.S. tube rusting after welding
RE: 455 S.S. tube rusting after welding
Another possible source of contamination can come from the cutting tool itself which may contain iron. It is better to use diamond cutting tool at least for the final machining.
Did the plater pickled the part before passivation. The pickling dissolves the iron parts that came from the m machining process.
However picking produces hydrogen. Therefore, if the parts are treated to H900 there is a real risk of hydrogen embrittlement of the parts.
The correct cleaning method should be abrasive cleaning such as aluminum oxide blast of the part surfaces before and after welding. If the inside diameter of the tube is too small you can use a paste abrasive cleaning as used for stainless tubes used for microelectronic industry where a paste with abrasive particles is pushed/flow through the tubes using pressure.
After abrasive cleaning there is no need for pickling just solvent cleaning and passivation.
RE: 455 S.S. tube rusting after welding
Thank You Again
Phil Lohiser
RE: 455 S.S. tube rusting after welding
RE: 455 S.S. tube rusting after welding
RE: 455 S.S. tube rusting after welding
RE: 455 S.S. tube rusting after welding
I believe that the surface in question may not be clean enough to start with, isn't purged enough, and has not been passivated.
What are you using for passivation?
You may have too much surface damage for passivation to do its job.
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