535 Almag or Magnesium casting for race car suspension 1

[WagEng]

We build FIA race cars and are trying to get stronger suspension uprights(knuckles). This is a fatigue-loaded part. We are currently using A356. Our casting foundry has suggested using AlMag 535 because of the superior elongation and slight weight reduction.

The weight reduction would be nice. If we were to go all the way, a Magnesium upright would be very light. Any suggestions? I know they build racing wheels out of Magnesium.

Thanks for the help!
Todd

 

[swall]

Although the ultimate tensile strength of 535 alloy is not much lower than that of 356, the yield strength is significantly lower. So, with given section size, your part will not be as strong. I think your main options for higher strength lie with 357 or 201 alloy. 201 was used on the rear suspension "knuckles" for the 1990 era Ford Thunderbird (MN-12 platform). As far as I know, it was satisfactory in the application.

 

[swall]

Oops--I meant to say 206 alloy, not 201. 206 is the non silver containing version of 201. You could, of course use 201, but it is more expensive.

 

[WagEng]

Thanks. My thoughts were trending that way, but our casting shop was pushing 535.

I've been thinking of doing some geometry changes and going all the way to a Magnesium alloy. I'd hope for some vibration reduction in addition to the weight savings.

Any thoughts on using Magnesium for a racing suspension part?

 

[CoryPad]

If you are to use magnesium for racing suspension parts, the best solution is to use a wrought alloy for the highest strength (static and fatigue) possible. Formula One wheels are forged magnesium, not cast. Alloys to investigate for your parts include AZ80, ZK60, WE43, & WE54. If you must use casting, there are casting versions of the alloys listed above. Try to use a high integrity process like squeeze casting or vacuum die casting. If you must use gravity die casting, sand casting or investment casting, try to use HIP (hot isostatic pressing) after casting to improve properties.

Regards,

Cory

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