HRS vs. CRS

[lynnl]

I'm looking for some education here:

How does one know when one is looking at cold rolled vs hot rolled steel? I've always assumed that angle stock, or for that matter any structural steel, is hot rolled.
Also if it appeared to have a rust/scale layer (other than out in the weather too long) then it's HRS, whereas CRS would be cleaner looking. But I'm never sure.

Also, if 'stressproof' is called for, will drill rod work ok?

[metal mite]

You know when you put a tool to it.
Hot rolled is a better material by nature
having fewer stresses and better machinability.
As a result, parts have less distortion while machining.
Cold rolled steel is generally trash.
mite

[SGW]

I wouldn't categorize cold-rolled as "trash." The composition of the steel has far, far more to do with the "trashiness" of steel than how it's rolled. In fact, I many better grades of steel are cold-rolled, because the cold-rolling process strengthens the steel and imparts other desirable properties.

Generally, I don't think there is any 100% reliable way to tell the difference. As you note, hot rolled has a surface scale, but that can be difficult to identify if the steel is weathered.

"Stressproof" is not equivalent to drill rod. It's another thing entirely. It's a trade name of LaSalle Steel for 1145 steel that has been manufactured in a certain way. "Fatigueproof" is similar in composition, differing in the the manufacturing process.
Both of them machine very nicely -- a heck of a lot better than drill rod or any of your typical hot- or cold-rolled "mild steel."
Do a web search for "Stressproof" and you should turn up a bunch of information.

[Rotate]

My local supplier charges more for CRS than the HRS. From what I've been told, the CRS machines more nicely, however I've used both and frankly with the shallow cuts that I usually make, I don't see any difference. Even the metal vendor's can't tell whether it's CRS or HRS after it's been machined.

BTW, I've used 12L14 and it does machine nicely however it doesn't seem very popular so my supplier doesn't stock too many different sizes. Why is this?

Is 1145 just as nice to machine as the 12L14?

Albert

[metal mite]

Hot rolled steel is rolled "hot", red hot.
What you get is a material that has few stresses and in the annealed condition.

Machinists don't like to work it because it's DIRTY. How about that used oil slime put on c.r.s.

COLD ROLLED steel is rolled cold which workhardens the surface (good for some applications) but also stresses the same surface.

You take a cut on one side of a piece of c.r.s. 1/4 inch thick, and end up with a potatoe chip (exagerated).
This is not the case with hrs.

Cold rolled steel is ok if you need something that looks nice with minimal machining.

Hot rolled is best when heavy machining is required.

Take a piece of c.r.s. and saw down the center to make a yoke. Your saw cut will spread to 1/8", 1/4" or more.

What you get is a Y shaped part which needs the outside cut to true it up anyway.

May as well get h.r.s. to start, and machine it all over anyway.
Save money in the long run.

Higher price dosen't make better material,
just more expensive.

metal mite

[bspooh]

I use CRS more often because it holds truer in the chuck...Hot rolled is no problem to machine, as long as you cut deeper than the crust on your first cut....

And yes, CRS has stresses because it is cold worked..If you are going to make parralels, use hot rolled because cold rolled will warp as you machine it...I use 1144 not 1145 and it is a stressproof material..

12L14 machines nicely because of the lead...The only difference between 1214 and 12L14 is the added lead....Lead increases machinability, Lead does not do anything else in the material.....Do you notice the difference in smell???

brenbt

[SGW]

Is Stressproof 1144? Could be...I can never remember if it's 1144 or 1145.

Anyway...I like the finish I get with Fatigueproof (never tried Stressproof, but supposed to be similar) very much. You can't cut it quite as fast as 12L14, but it cuts well (it doesn't "tear" the way drill rod and some mild steel does). I don't care for 12L14 all that much because I find that it rusts really easily. But it sure does cut nicely.

[bspooh]

1144 is stressproof..I use a lot of 1144 for making high pressure hydraulic cylinders...It is pretty easy to maintain a 16 RMS finish....But it does work harden semi-easy...Be careful when you drill!!!

brent

[bighammer]

Cold finish steel (most isn't rold now) is drawen through a die, lots of stress in it. It will sometimes warp or go cork screw or go egg shape on you, sometimes all three. It is best used for shafting and such where you only have to cross drill it for a pin, cut a keyway or make a short thred on it. It is usually close to size, most of what I get is .0015 or .002 under. Just right for a little oil room in low speed bearings. Hot finish steel is much better for machining after you get past that scale, it don't warp but it is hard on end mills. Pickle it first in salt and vinegar after you degrease it if you can. Can take three four days to pickle but it will get rid of the scale. Also most hot finish steel I get is not very round any more, and it will mot clean up in the lathe to the stated size. I have to buy 15/16" to clean up to 3/4". That said once it in the scrap yard and rusted up you can't tell them apart till you go to turn them. If you buy your steel from a warehouse you should be able to tell by using a rag or scraping it with an old knife or file.

Cookie

[spope14]

I am partial to 11L17 or 12L14 or even without the lead CRS for most applications. I make parallels out of 41L50 CRS. To remove warp I mill surface light off one side, mill opp surface same - no warp here, go back to orig surface, seating on second surface, works like a charm. Most I have to take off the stock to do this is about .070 at best total stock removal.

I have had warping trouble with Hot rolled as well. The cold rolled idea is just how you work off the surface to remove stress.

I also use quite a bit of 4140 Cold and hot rolled in my shop, seems the cold rolled machines better. I can't really tell the difference after the surface cuts.

Best way to tell cold rolled from Hot rolled in the field when weathered. The hot rolled has the surface scale, the cold rolled does not. I will take a piece of 50 grit sandpaper with me and sand off some rust. If I get to steel immediately, it is cold rolled. If I get a bit of blackened dust and the surface scale shows through better, it is cold rolled. Good about 80% of the time, sand off the rust a bit - do not work too hard or you negate this.