Dilivar Specifications

[magnograil]

G'Day,
Would anyone have the density, coefficient of expansion and tensile strength of Dilivar? It is used in the Porsche 911 engines for the through studs. I believe the coefficient of expansion is about half way between aluminum and steel. I had no hits on this question from the Materials forum.
Thanks.

 

[tbuelna]

magnograil,

I've never seen any data for Dilivar. I'm sure it's a proprietary alloy.

However, if you want a good fastener material with a CTE fairly close to aluminum, take a look at A286 cres. It's a common fastener material, has good tensile strength (146 ksi uts), responds to heat treatment, is corrosion resistant, has a CTE between aluminum and steel (9.4 x 10-6 in/in-degF), and is readily available.

http://www.matweb.com/search/SpecificMaterial.asp?bassnum=Q660AC

Regards,
Terry

 

[EngJW]

Must be a trade name. I just searched and couldn't find anything either. Take a look at the link below, and page down to the section on high and low thermal expansion alloys. It is probably similar.

http://www.key-to-steel.com/Articles/Art9.htm

 

[magnograil]

Thanks to both. I checked the name in a Porsche performance handbook and it is Dilavar, sorry. I know one problem is fracturing from corrosion. Even newly installed parts will sometimes break within a few hours of being torqued. Probably due to hydrogen embrittlement. The latest parts have a gold colored coating or an epoxy finish. My understanding from hard chrome plating is the hydrogen can be removed by heating to about 400F for four hours. I hope the same applies to Dilavar.
I will check out the A236 alloy, thanks. My application is the Norton rotary that currently uses 1/4" through studs and for some inexplicable reason they put 1/4"-28 Heli-coils to retain the studs in aluminum. If there is enough material around the holes I can possibly change to 7mm Time-serts.