Stronger then 7075-T6 for car axle

[petersi]

My friend has a machine shop so I can easily have access for his labor of making some parts of my toy.

I have a transmission axle made by 7075-T6 and it last about 40 hours of running. I want to use something stronger but easy on machining. I checked around, this 15-5 PH Stainless Steel Condition A (annealed) is very strong almost double then 7075-T6:

Ultimate Tensile Strength, psi 161,000
Yield Strength, psi 140,000

The more stronger material the longer last of the axle. But I want something easier to machine or may be something less stronger then heat treatment after machining. This would work too.

My goal is to find a material that can last 60hours of running or say 1/2 stronger then 7075-T6. What do you recommend? This is just for my toy. Nothing needs engineering calculation. Thanks a lot.

 

[SnTMan]

Not really my field of expertise (if any) but see...
thread330-21337

Regards,

Mike

 

[blacksmith37]

Maybe I don't understand; why wasn't it steel in the first place ? Any Q&T Cr :Mo like 4140 will far exceed the the fatigue life of aluminum (with similar dimensions).

 

[MikeHalloran]

Stressproof is great stuff, but beware that it comes with a microcracked 'bark' on it, so buy rounds 1/4" oversize, or buy the prefinished ground and polished "Stressproof G/P" grade in the exact size you need.




Mike Halloran
Pembroke Pines, FL, USA

 

[petersi]

The only reason to use 7075 is to provide lighter rotation mas. So the car can run faster. But they will worm out of breaking after 40 hours of running.

 

[swall]

You might consider a tubular shaft. I have seen axle shafts made from gun drilled 4340.

 

[petersi]

Thanks. Some of my parts already using tubular shaft like pulley shaft, gear shaft. For axle, my axle is like 5mm thick. I think the tubular shaft design should not work. But thanks a lot for your suggestion. I'm now thinking to use S45C steel then heat treatment. I think this will be a lot strong then 7075. i guess more durable.

 

[ornerynorsk]

7068, but be aware max operating temp is around 300 F.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.