Magnesium Alloys

[Alex]

Am I right in thinking Mag Alloys have to be x-ray checked yearly as they are more likely to suffer hairline fractures and metal fatigue with catastrophic failure?

 

ie Mag Alloy TE-37's may save you 10lbs a wheel but they only last a year?

[Chris Wilson]

Road car wheels only have a bit of mag in them, race car ones often have a very high mag content. Most of the high end race car series now have the RAC MSA dictate that critical parts are independently crack tested. Won't be a problem for the wheels you cite though, they are much more durable, with much less mag in them than a proper race wheel. If you need it doing though I have an account with an accredited x-ray inspection place.

[Alex]

Ahh that's good to know.

 

Thanks for the reply Chris.

[Steve Cargill]

Going off on a bit of a tangent, wasn't there a big crash at Le Mans in the fifties when a car (Merc??) broke up and sent lots of burning magnesium into the crowd and killed about 50 people.

 

I assume that even the higher spec race wheels couldn't do that - probably as they are alloy and I guess it was pure magnesium they used then.

[Paul]

My Speedlines are Magnesium, as said before though alot less content for road ones.

 

I had a chat with the tech guy at speedline and he bored the arse off me but told me some interesting stuff.

My 1908's have a hard coating between the paint and the alloy, to not only make them more durable but to reduce the moisture absorbed as magnesium is hydroscopic (I think that's the word?).

He said that they get heavier with age due to the moisture absorbed and I guess weaker?

 

He also said they had a set in for refurb that were about 25yrs old and they had no problems with them so they do last OK.

Mine had x-ray pass stickers on them so they must x-ray when new but he said there was no need to do this in future unless of major whacks or damage.

 

Paul

[Digsy]

Originally posted by Paul

My 1908's have a hard coating between the paint and the alloy, to not only make them more durable but to reduce the moisture absorbed as magnesium is hydroscopic (I think that's the word?).

 

Yeah, it's why you can't make items like cylinder heads or blocks out of an alloy with a high Mg content unless you do some fancy treatments on the coolant passages. It will actually dissolve eventually.

[SimonB]

Originally posted by Steve Cargill

Going off on a bit of a tangent, wasn't there a big crash at Le Mans in the fifties when a car (Merc??) broke up and sent lots of burning magnesium into the crowd and killed about 50 people.

 

The worst crash in motor racing history, at Le Mans in 1955, 79 people were killed. Basically two cars hit and the Merc hit the bank and disintegrated, the entire engine flew out and straight into the crowd, decapitating everyone in the front row. The body was made of an aluminium alloy that caught fire in the petrol fire IIRC, but most of the damage was done by the debris. Racing is still banned in Switzerland following that.

[crimbo]

I've machined magnesium components for under-carriages to go on commercial aircraft. it is highly flamable and burns at extreme temperatures, (as swarf it can melt a m/c bed). These components put up with a few tonnes crashing down on them, but i never heard of them having to be x-rayed..... after they leave the workshop.