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Different Grades Of Mild Steel??


What A Joke
Alright I got a question for you metal guys.

My back bumper is made out of .95 1 1/2". This thing has been hit, slamed, banged, everything and it only has one little dent in it.

Now my front bumper is made out of 1 1/2 .120 and Its bent from not even hitting that hard at all.
Also my shock hoops are made from 1 1/2 .120 bought at the same time as the bumper. And the actually metal itsself flex's and bends a little!

I was just wondering if its possible I got a bad batch of Mild Steel when I bought this metal or what?? Or is their different grades of Mild Steel??

Go Big Or Go Home


Well-Known Member
Sounds like to me, that the rear bumper was made out of D.O.M and the front bumper on your truck and the shock hoops were made out of Cold Roll mild steel. Both types are mild steel, but D.O.M. is seamless and alot stronger than CR.Also, just in case...make sure that you really got .120 wall tubing. Measure the wall thickness! Also, "Design" could have alot to do with it too!

Grades of Mild Steel that I'm familar with:
Cold Roll (stronger than Hot roll)
Hot Roll (not very strong)
Seamless, D.O.M. ( Stronger than Cold Roll and "almost" comparable to 4130 in "strength")
Anyone else wanna guess?


Well-Known Member
There are many different grades of steel tubing. There is as-welded carbon tube normally supplied in 1008 or 1010 grades. There is cold drawn seamless carbon tube normally supplied in 1018 or 1026 grades. There is drawn over mandrel (DOM) carbon tube normally supplied in 1020 or 1026 grades. There are others and also your alloy grades of tubing.

If you don't know much about different grades of steel, the last two digits represent the percentage of carbon present. For example, 1018 steel contains 0.18% carbon and 1026 steel contains 0.26% carbon. The increase carbon content increases the mechanical properties of the metal.

If you would like a better selection of tubing or you want to speak to a sales rep that really knows what he is selling, call Tube Service at 310-695-0467. Besides, it is always good to support your fellow racers. (TSCO - Wehyrich class 1)

"The only source of knowledge is experience." - Albert Einstein


What A Joke
Well I know for sure the back isnt DOM cause I made that too. Its got seams.

I have checked the wall and it measures right.

How can you tell the difference between Cold Roll and Hot Roll? Maybe the front is Hot Roll.

Go Big Or Go Home


Well-Known Member
Re: How can you tell the difference between Cold Roll and Hot Roll?

If it was made from hot roll it would have a very rough texture to it. You might be refering to schedule pipe.


"I know it all, but I can't remember most of it..."


- users no longer part of the rdc family -
Maybe you hit your front bumper harder than you thought. Imagine what your rear would look like if you off roaded in reverse all the time! Also, if you follow people a lot rocks are flying everywhere.


Well-Known Member
While we're on the subject.
Haven't seen it named as such in tube, but in plate there is a whole family of mild steels called "HSLA", High Strength, Low Alloy. Low alloy meaning the carbon content is still within the "Mild" steel classification. These tend to be referred to by trade name rather than ANSI numeric designation. Common names that I'm familar with are AR (Abrasion Resistant), T-1, Core-10, & Ten-x, but there are others.
HSLA's are what you want to use when gusseting forged spindles and similar parts as the alloy tends to be far closer to what steel forgings are.


"Teach you all I know and you're still stupid"
-- Howdy Lee


Well-Known Member
Hey Brad,

Thanks for that great explanation on D.O.M. (I always wanted to know what that acronym stood for) and steel tubing in general. In your post, you mentioned that the increase in carbon increases the mechanical properties of steel. Please forgive my ignorance, but what does that mean? Does that mean that an increase in carbon makes the mild steel softer or stronger? Or does it mean something completely different?

Take care,

Ed Q.


Krittro Campbell
Strength increases, ductility decreases with an increase in carbon.


"A man with a watch knows what time it is; with two watches, he is never sure" Joseph E. Shigley