View Full Version : What is chromemoly?
I've seen a flywheel advertised as being made out of this?
What is this material?
What's good about it?
28-05-02, 03:12 AM
In short, chromemoly is an alloy of metals to produce a final grade of product.
Its full name is Chromium Molybdenum Steel.
I would suggest that it would contain some high carbon steel, stainless steel for corrosion resistance, chromium for luster and strength, etc.
heaps of things are made out of chrome moly steel, such as push rods, bike frames, engine components, flywheels, gears, etc.
Each specification has its own individual properties, so generally speaking it would be a high grade for a flywheel.
Essentially, the benefits in terms of flywheels could mean more strength than steel, lighter, 'shatter proof', more heat tollerence, etc.
Alloying metals is one of the best ways to customize metals to the market specific needs.
Chrome moly is not actually as strong as mild steel, but it is 'stiffer'. So it won't flex much as you put a load on it, but it tends to break if you overload it, unlike mild steel which will probably just bend.
Its used in components where stiffness is critical (such as a racecar chassis). Things made out of chrome moly can be lighter because you achieve the same level of stiffness with a smaller section size than with mild steel.
I was inquiring about putting a roll cage in my car a while back...and the guy said that chromoly was the best material as its the lightest but the strongest....I didnt realise it snapped like Aluminium though.
29-05-02, 12:19 AM
Kalium, don't worry, it doesn't snap like aluminium at all.
My day job is to fabricate repair and weld sprintcar chassis' so we use it and Tig weld it all day.
As FeTt said, it's used because in racecar chassis fabrication you get a weight benefit. On any given mild steel thickness you can go significantly thinner and still have excellent strength.
The yield strength of mild steel is approx 350mpa, Cr/Moly is 650mpa so you can see why we use it.
Basically every professional form of motorsport using tube frame cages or chassis' use Cr/Moly, from top fuel, funny cars to sprintcars and supercars.
We are probably the largest user of Cr/Moly outside of the defence department in Victoria.
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