Like the subject line says..

Whats the difference between chrome moly and mild steel???

TIA..

 

Cro-Moly is an alloy of steel that includes certain quantities of Chromium and Molybdenum. Mild steel is just Iron and Carbon.

Ahhh metalurgy! My head hurts now.

Cro-moly is stronger, can be more brittle, is harder to weld properly - and more expensive.

 

Cro-moly is strong BUT can be more brittle?? care to expand on that statement?

TIA..

Dan

 

Kind of like iron is strong but more brittle than steel. I think it is hard but doesnt give, and when it does it breaks. From everything I have heard you want to use mild steel for street use.

Ben

 

Why? I hate to drag this thread on and on but I really want make the best suspension setup for my car. Price isnt a hugh concern but a concern none the less.

Later..

 

Uh.... Because Chrome moly is brittle and can break with street use(repeated bumps in road and pot holes and such).

Ben

 

Unless you're racing and trying to remove or relocate as much weight as possible, you don't need chromoly. The extra cost doesn't justify the slight weight reduction from mild steel.

My mild steel 6 point roll bar is 70 pounds. If it was made out of CM it might weigh 50 pounds. It would then need to be welded up with a TIG instead of MIG.

 

it also depends on the guage of chromoly. certain places make their chromoly pieces with a thicker guage that is heavier than most but lighter than the mild steel costing very little and helping to save weight all while being just as strong as mild steel for the street.

true racing quality CM does risk the chance of problems down the line. not to say you couldn't use it on a street car as alot of people do. you just have to use your head and avoid ditches or bone rattling pot holes.

when the time comes for you to have to make the choice just ask the people who are making your product. they will know what you need. real lightweight CM does cost a bit more, the thicker stuff isn't to much more and will save the weight.

but, look into it yourself and learn....it's the only true way to protect yourself.

 

use a good grade MS, actually maybe a HSLA MS and you'll be way ahead. way back when i was building chassis CM wasn't all the desireable because it was so rigid, and we had to use tubeing of a set size so going smaller wasn't an option and we had to run a minumin weight anyway. CM tends to crack because of it's tendency for hydrogen embrittlement and has to welded with GTAW or more commonely called TIG. to anser your original question the differance between CM and MS is (drum roll please) the addition of molybendium (sp?) as an alloying agent.

 

Just wanted to thank everyone for their input.. Unfortunatly Im someone that will never learn that "bigger isnt always better." In my mindset.. if a product costs more than another it has to be better right?

One last thing. What does HSLA stand for ede??

Later..

 

high strength low alloy if you have access to a metal catalog you'll find some steel designated by HSLA, it'll list the specs and composition of the metal. my ryerson catalog is at work or i'd give you a better example.

 

Moly for the track, mild steel for the street. The moly is lighter and stronger, but it fatigues quicker. I went through all this about two years ago. For the street the weight savings is not worth the fact that you may need to replace it someday. Do not get me wrong, mild steel will fatigue also, just not as soon.

 

very true but understand there are different grades of CM just like there is with MS.

check with the company first to be sure; some companies offer thicker CM which is better than other companies MS and weighs less.


just know all your options before you make your decision and question everything.

 

This is a good thread... I think I'll add my opinion to it. As far as chrome moly being lighter than mild steel, just look up how much each one of them weigh. I think you'll be surprised to find out they both weigh almost exactly the same. Now, the way you get a chrome moly part lighter is to go thinner on it. I had PA Racing make me a chrome moly cross member for my street car and just had them make it the same thickness (120 wall) as mild steel ones, so my chrome moly cross member is the same weight as a mild steel one, just a lot stronger.
On the point of fatigue, that is usually because you are running the part too thin. If chrome moly was brittle and easily fatigued, then please send me your chrome moly parts. We can start with your crank shaft, rods, push rods, valve spring retainers, axles, and any other chrome moly parts you don't like. So don't be afraid of chrome moly parts, most people have hundreds of them in their cars.

Jerry