Summary for stress relieving brazed stainless copper Discussion
Stress relieving a brazed stainless & OFHC copper assembly is questioned by Nathan Rummel, who asks for temperature, time, and cooling conditions that would relieve a 304L stainless part without softening the copper. The reply from an answerer in McHenry, Illinois says the first issue is whether this is an academic exercise or a practical need. They note that stress relieving austenitic stainless steels is generally only needed after cold work, and suggest it would be more sensible to perform any needed stress relief before brazing the copper to the stainless. The answer also points out that the annealing conditions for 304 should be easy to find, but if those conditions are not compatible with the copper, then there may be no workable post-braze solution. The thread therefore leans toward avoiding post-braze stress relief rather than giving a specific safe cycle.
Q. I’m doing some research into the stress relieving of of a stainless steel part (304L) that has been vacuum brazed to OFHC copper. My issue is finding the correct set of circumstances (e.g., temperature, heating time, cooling time) in which this can be done while keeping the copper from softening. Any information on the subject would be appreciated
Nathan Rummel
Student – Pittsburgh Pennsylvania
May 31, 2017
Ed. note: This RFQ is outdated, but technical replies are welcome, and readers are encouraged to post their own RFQs. But no public commercial suggestions please ( huh? why?).
A. Nathan,
Is this just an academic discussion or is there some practical purpose to it? Stress relieving of austenitic stainless steels would only be necessary if they have undergone cold work. It seems more reasonable to take care of the stress relieving before brazing the copper part to the stainless in the first place.
Anyway, the annealing conditions needed for 304 should be easy enough to find, and if they aren’t compatible with your copper, then I’m not sure there’s anything to be done.
Ray Kremer
Stellar Solutions, Inc.
McHenry, Illinois
June 14, 2017
Q. This is practical, I’m doing some research for the company I’m working at on stress relieving for one of our parts that has been experiencing some warping of its stainless steel base after extended time in service. The part can’t be fully annealed because of the lower solidus temperature of the braze filler (which is around 780 °C), We also would need to keep the hardness of the copper from dropping too much as to allow us to do the diamond turning necessary for the parts finish. What I’m looking for is a set of temperature and heating times that we might be able to use to accomplish this and at the least extend the service life of the part.
Nathan Rummel [returning]
– Pittsburgh, Pennsylvania
June 15, 2017