Stress relief of BeCu

[marshell]

I am trying to minimize the Bauschinger effect in a 1/4H BeCu (UNS C17200) wire, that has been formed. How would I find the time and temperature to achive this? Would the standard 600deg F for 2 hours remove the stress?

If the heat treat does not remove the stress, is it possible to Stress relieve the wire, then heat treat it from 1/4H to a 1/4HT without inducing more stress on the part?

Thank You,
Marshall

 

[metengr]

Marshell;
What was the condition of the BeCu wire prior to forming? From literature that I have seen on BeCu alloys, they can be strengthened after forming by an aging heat treatment. IF the wire was heat treated prior to forming, performing a stress relief will result in overaging. I think this would enhance the Bauschinger effect.

The typical precipitation hardening heat treatment for C17200 is to anneal between 1400-1450 deg F, rapid cool and reheat at 600-650 deg F for 3 hours to achieve peak strength. Any reduction in temperature or time during aging will result in underaged properties, which may be acceptable for your application.

 

[marshell]

The condition prior to forming is 1/4H. I am thinking of performing a HT of 600deg F for 2 hours to take it to 1/4HT. I believe this will also stress relieve it, but I want to make sure.

Thanks,

Marshall

 

[metengr]

Yes it should. This alloy can be used in a solution treated/precipitation hardened condition, solution treated/cold worked condition or solution treated/cold worked/precipitation hardened condition. Stress relieving the BeCu alloy is performed at 300 deg F for 2 hours - this should relieve forming stresses but will alter the 1/4H (TD04) cold worked temper, not the TH04 temper.

Heating to 600 deg F for 2-3 hours should stress relieve (because you would be above 300 deg F) and establish the TH04 temper provided the BeCu alloy was annealed and water quenched, prior to work hardening to the TD04 temper. If the BeCu was not properly annealed and water quenched, heating up to 600 deg F will not strengthen the alloy.