Steel for Skateboard Truck Axles
Steel for Skateboard Truck Axles
(OP)
So after searching for many long hours and constantly being directed back to eng-tips.com I decided to join as I always seem to have many questions. I make downhill racing trucks for skateboarding and we are looking for a new steel for our axles. The axles are 8mm in diameter, 10" long and they are pressed into a 6061 aluminum shaft. We are currently using 17-4 stainless steel heat treated to a h900 condition.
We have been looking at some maraging steels and other steels but I was hoping to get some good advice from someone who knows what they are talking about. So we are looking for a metal that has:
High strength at temperatures under 120 F.
High elongation % (bending it better than breaking)
Medium to High corrosion resistance (they are constantly used in rainy and even salty conditions).
And the lower the cost the nicer :)
Any help would be greatly appreciated. Thanks very much.
We have been looking at some maraging steels and other steels but I was hoping to get some good advice from someone who knows what they are talking about. So we are looking for a metal that has:
High strength at temperatures under 120 F.
High elongation % (bending it better than breaking)
Medium to High corrosion resistance (they are constantly used in rainy and even salty conditions).
And the lower the cost the nicer :)
Any help would be greatly appreciated. Thanks very much.





RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
Maui
www.EngineeringMetallurgy.com
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
A 250ksi maraging steel would work, but they are tough to work with. I would not use a 300ksi maraging since these have lower fatigue strength.
You could look at 17-7PH in RH950 condition. I would avoid the CH condition as it has very low ductility.
You need to look at your design carefully. If you can increase diameter slightly it would help a lot. You also need to make sure that you avoid sharp corners.
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Plymouth Tube
RE: Steel for Skateboard Truck Axles
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Steel for Skateboard Truck Axles
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Plymouth Tube
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
Are these failing from straight overload or from fatigue?
Right no you are at 170ksi min Yield and 190ksi min UTS
going to 17-7PH in the RH900 will get you to 190ksi min Yield and 210ksi min UTS.
A 250 maraging will get you to 250ksi Yield and 260ksi UTS.
Or a 300M will be about 290ksi Yield and 300ksi UTS.
For this service you may really need to think about how to get more diameter. I know that means incompatible hardware but it may be the only way to get enough strength.
If it was me I would use a 250 or 300 maraging (depending on availability) and see how it goes. That is a good step up in strength.
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Plymouth Tube
RE: Steel for Skateboard Truck Axles
1.) They are elastically deflecting by an unacceptable amount while under load? Or,
2.) Are they permanently deforming so that when the load is removed (i.e. the rider steps off the board) the axles don't spring back to their original undeformed condition?
If the first scenario is what you are describing, then increasing the tensile or yield strength of the alloy won't make any difference. Either you need a steel with a higher elastic modulus, or you need to increase the physical diameter of the axles, or both. You can read FAQ FAQ330-1441: Why is the elastic modulus relatively insensitive to changes in chemistry/heat treatment/coldwork? to understand why this is the case. If #2 above is what you are describing, then Ed's suggestions are certainly good advice.
Maui
www.EngineeringMetallurgy.com
RE: Steel for Skateboard Truck Axles
Maraging 300: $27/ft, Ultimate TS: 2169 MPa Yield TS: 2135 MPa Elongation: 7.70 %
13-8mo rh950: $11.27/ft, Ultimate TS: 1620 MPa Yield TS: 1480 MPa Elongation: 12.0 %
Custom 465 h900: $6.98/ft, Ultimate TS: 1779MPa Yield TS: 1703MPa Elongation: 14.0%
The custom 465 comes in a slightly bigger size but I know a place that can precision grind it down for about $5-6/ft. Both the maraging and 13-8 come in 8mm. Another cost would be to heat treat the 465 and 13-8. Not sure if I can just keep the maraging steel how it is.
RE: Steel for Skateboard Truck Axles
RE: Steel for Skateboard Truck Axles
Since you can get 465 in nearly the correct size that sounds like the winner.
It should come to you annealed. You would machine and then heat treat at 900F for 4 hours, and oil quench. Not a lot of trouble. You can do it in air if you don't mind the heat tint.
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Plymouth Tube