Hydrogen embrittlement

Edited By meyrick griffith-jones on 18/12/2009 11:02:06

 
Hi everyone

Ian - I seem to recall the de-embrittlement temperature is around 190 deg C and has to be done 4 to 6 hours after the coating process and baked for several hours. If not done in the required time span hydrogen becomes permanently trapped and the heat treatment does not work.

 Meyrick - It's actually a 3" Allchin I am building but a Burrell is close enough. The parts in question are for a motor cycle restoration project being done by a freind, he gave me some large socket head cap screws (probably 12.9 grade material) from which to make the parts and wants to get them black phosphated. It occurred to me that with this material hydrogen embrittlement might be a problem.

 Kwil - I did not mean to infer that hydrogen embrittlement is a problem with anodising, only that by treating the component surface the load bearing capacity was effected. I think perhaps the anodised surface in less ductile and more susceptible to suffering a minute crack under certain loading conditions from which a larger crack may propagate especially in a cyclic loading condition, only my guess.

 I conclude that de-embrittlement is a safer route just in case. At 190 degC it can be done in a domestic oven.

Thanks for your helpful comments

 Nigel

Edited By V8Eng on 18/12/2009 19:31:16

Edited By V8Eng on 18/12/2009 22:01:17

Edited By V8Eng on 20/12/2009 18:56:01

Edited By V8Eng on 21/12/2009 21:20:13