if Norton parts and customs were as conistent as major modern water cool engines then one size fits all bottoming torque spreader might apply but other wise nope. Non ferric cryo treatment [so tempering term don' apply] like women nylons, guitar strings, copper electrical components etc is very contraversial except to those repeat customers with real life results. For those capable why not get some alloy similar to our heads and test threads before and after cryo treatment which takes a couple-3 days to do right. Alu is claimed to resist deminisonal changes, cracking and wear better - more than increase failure strength but that seems enough to make some hot head racers and NASA repeat customers.
Frederick (Materials) 3 Oct 14 11:00
First a word of disclosure. I own a cryogenic processing firm. I am co-chair of the ASM Cryogenic Committee. I have hosted ASM webinars in concert with a NASA engineer and a metallurgical engineer from Air Liquide. I think I can speak with authority on the subject.
The paper that tbuelna cites is named Effects of Cryogenic Treatment on the Residual Stress and Mechanical Properties of an Aerospace Aluminum Alloy, by PO Chen et al. The conclusions the researchers came to were:
1. Residual stress was reduced by up to 12 ksi in the HAZ of weld specimens and by up to 9ksi in the parent metal.
2. Significant improvements in SCC (Stress Corrosion Cracking) performance were seen for weld specimens.
3. Minor increases in tensile strength and hardness were noted for parent metal.
4. No significant changes were found in the tensile properties for weld specimens or in fatigue properties for parent metals.
Nowhere does this paper state that DCT is not very effective with most aluminum alloys. The research only covered one alloy and the results were listed for "this particular alloy."
Effect of Cryogenic Treatments on Mechanical Properties of 2A11 Aluminum Alloy, Wag et al, Advanced Materials Research Vols 146-147,(2011) pages 1646-1650 states: "The influences of different process parameters on mechanical properties of 2A11 aluminum alloy were compared, and the results showed that cryogenic treatment could improve mechanical properties of 2A11 aluminum alloy. The dimensional stability increases after cryogenic treatment once, and increases further after cryogenic treatment again."
More are available on Google. The point is that the DCT has been tested and found effective on aluminum alloys. The practical tests in use on engines is also significant. Our customers have reported 5 times the life on racing engines. One was a national champion go kart racer racing a Briggs & Stratton engine.
Too much more here if interested
http://www.eng-tips.com/viewthread.cfm?qid=372224
