Hot rolled or cold rolled?

[andreas]

I've been asked to make a fireplace grate for a family friend. I was wondering if there was any advantage to using cold rolled steel instead of hot rolled for this project. I've read somewhere that the cold rolled may last a little longer.

[ThomasPowers]

No without specifying the steel they both could be the same alloy! Like hot rolled A36 is pretty much the same as cold rolled A36. Cold rolled has prior work hardening but as soon as it's come up to temp in the forge the work hardening is gone and the unscaled surface is gone too.

Now if you want something to last longer go with stainless steel---however it's a pain to forge, eats abrasives during finishing and costs more to start with. Most smith have a substantial premium on making stuff from stainless to cover all this.

[Timothy Miller]

Tomas hit the nail on the head there should really be no difference in durability between hot rolled steel and cold rolled steel. Cold rolled steel is more expensive than hot rolled it is typically 1018 alloy steel. It is descaled and rolled cold this gives it a silvery finish and it is more precisely sized than hot rolled. It is work hardened from the cold rolling process this can make cold work difficult. it tends to be easier to forge hot than hot rolled/A36 due to its lower carbon and alloy content. Hot rolled steel tends to have a high scrap content therefor it's working properties can vary some being soft and some being quite hard it has a blue black finish due to the surface being covered in scale. It is generally harder to forge than cold rolled though it is cheaper and comes in longer lengths.

[MOblacksmith0530]

I find that cold rolled is a little more difficult to work until you have heated it enough to take out the work hardening from the cold rolling process. This can take more than one heat. I have also found it to be difficult to forge weld due to the refined grain from the cold rolling process. This seems to go away after normalizing for the most part. And with the cost being significantly higher I try to use it as little as possible.

[Daniel Lea (AKA 99pppo)]

I think you will be perfectly fine using hot rolled steel on this. Cold rolled steel has a little bit less tolerance in dimention and usually very sharp edges, furthermore it is a bit compressed short under the surface which makes it also a little bit harder and tougher. But hot rolled steel would be the one to go for the usual blacksmith...

[SReynolds]

I have been asked many times over what the number 10 means in my steel (1018) I really don't know. I also see that in 4140 etc. etc.

[Frank Turley]

Those numbers are a numerical index for structural steel types. The first two digits indicate steel type. The second number trys to indicate approximate alloy content. The last two or three digits try to indicate carbon content. This is a system of the Society of Automotive Engineers (SAE) and the American Iron and Steel Institure. You might be able to find a chart on line, because the chart is a bit lengthy. Ref your examples, 10 is a non-sulphurized carbon steel. The zero means no alloying. The 18 would be written as 0.18% carbon content. 41 indicates a chromium/molybdenum steel, and the 40 means 0.40% carbon content.

The SAE also has a numbering code for motor oil, which we all recognize.

[SReynolds]

Yes,,I have just studied that (SAE oil classification) is a class I recently took sponsored by an oil company. I didn't know that 50 weight engine oil is same weight as 90 gear oil.

The class was by Schaeffer's who sells that very highly overpriced oil and grease. I use some Schaeffer's just for fun. 21.00 per gallon. I don't use it as a quench though....LOL

THanks for the heads up on the #10! I have been telling folks that it means what you said, just not in the same words.

[HWHII]

I have replaced a fare amount of fire place grates. The biggest problem I have seen, is they are not built with heavy enough material. I tend to use 1" square or round and up for my grates. Even these will burn up or sag over time if you have a client who is a pyro. :huh: In these cases, I try to steer them towards andirons.

[ThomasPowers]

as for the steel designations: here's a nifty chart



10 series means its pretty much iron + a bit of manganese for sulfur control + the carbon indicated by the last two numbers, nothing else save for "tramp elements"

[SReynolds]

.....that is really sweet. That is exactly what I need for my shop. Thanks tons.

Is there a similar chart for the steel(s) like the A36 classification(s)???? I don't really understand what that would be as I have been told I had to buy some of that in the past as opposed to 1018HR or CF. I see some steel is also classed with an "S" prefix,,,,,maybe S7. Thanks

[Chuck_Steak]

A36 refers to ASTM A36, "Standard Specification for Carbon Structural Steel". This specification has rather broad chemical requirements and the focus is more on the tensile properties that result. A36 typically has a chemistry of:

Carbon: 0.26 max.
Manganese: Not Specified
Phosphorus: 0.040 max.
Sulfur: 0.050 max.
Silicon: 0.40 max.

The important part of the specification is the tensile strength requirements of 58 - 80 KSI, yield strength of 36 KSI minimum, and elongation of ~20%. These properties don't really matter to us, however, as once you start forging the material you have most likely substantially altered the mechanical properties.

Basically you can consider A36 to be a 1018 to 1022-ish carbon steel.

The "S" steel you refer to is a tool steel, there are a whole slew of tool steels with various letters (S, M, T, A, etc). This is a different naming convention for a different class of steels as compared to the SAE steel grades. There are also stainless steels which typically have a 3 digit naming system (i.e. 304), which is another variation on the numeric naming system.

http://en.wikipedia.org/wiki/SAE_steel_grades

That link covers alot of the common naming systems in the US.

[SReynolds]

I was sold some A36 in the past as they didn't have the 1018 in stock and in the form (shape) I needed for my decorative art work. Thank you for the link.

[thingmaker3]

The last two number in a 10 series designation simply specify which designation is being talked about. There will be a range of both carbon content and a range of manganese content for each and every different 10 series designation.

You have to actually look up the number on the chart to know what those last two numbers mean!!

[thingmaker3]

double post

[ThomasPowers]

The last two numbers refer to the carbon content in points with 100 points equaling 1% C. What you have to know is the allowable range for each designation.

The exception of course is 52100 which has 1% C and thus a 5 digit designation.

see http://en.wikipedia.org/wiki/SAE_steel_grades for a more through discussion.

[thingmaker3]

The last two numbers refer to the carbon content in points with 100 points equaling 1% C.

That is a very popular myth, so of course the Wiki (which can be edited by any schmuck on the planet) will repeat said myth.

If we actually look at the AISI charts, only then do we see what the steel might have in it.

Have a look, for example, at 1064 or 1065... same carbon content range (as little as 60 points or as much as 70 points) but different manganese ranges.

http://www.engineersedge.com/materials/carbon-steel-2.htm

If I have a steel with 73 points of carbon and 60 points of manganese, I can sell it as 1069, as 1070, or as 1078. But is sure as heck won't be "1073," will it?

[ThomasPowers]

I note that it was cited as being from "Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (2003). Materials and Processes in Manufacturing (9th ed.). Wiley. ISBN 0-471-65653-4"

I'll have to wander over to the University Library and see if the textbook was quoted appropriately and check my Mat Sci texts and ASM handbooks as I recall it stated that way also.

Patrick, you got a minute as a working Metallurgist to give another opinion on this?

[Bob S]

That is a very popular myth, so of course the Wiki (which can be edited by any schmuck on the planet) will repeat said myth.

Thingmaker3,

Over the years I have heard this comment about wikipedia more than once. Personally I have found it (wikipedia) to be a pretty accurate source.

So just for fun let's pick out a section or even a single statement from the page cited by Thomas Powers (above) and change it. Since you brought it up and seem to think it's easy to do, why don't you do it?

First let's agree on the section you are going to change and after a bit of time for anyone interested to see the section in it's current form we can all watch you change it.

Easy!

Up for it?

[Timothy Miller]

Sounds like some major hair splitting going on here. Is this information really relevant to the question asked And for that matter is it of use to your average blacksmith. Perhaps a top knife maker may notice a .05% deviation in carbon or alloy content but the rest of us are not that particular. In other words your confusing the lad.

[andreas]

So, as to my original question, I'm good with hot rolled as long as it is heavy enough. Thanks guys. Carry on with the numbers / series / chemical compostion stuff.

[thingmaker3]

Thingmaker3,

Over the years I have heard this comment about wikipedia more than once.

My comment has to do with Wikipedia's masses over-riding the hard facts:

http://www.npr.org/2012/10/03/162203092/wikipedia-politicizes-landmark-historical-event

I consider any Wikipedia citation as argumentum ad populum.

Now if Thomas comes up with some primary reference to refute me, (and he's for sure the one who can if anyone can) I'll sit up and listen to him like I always do.

[Chuck_Steak]

The last two digits is very strongly correlated to the carbon content. That being said, as stated above, the numbers ultimately call out a grade and there are some variations in the manganese content for 10XX series steels.

"The last two numbers refer to the carbon content in points with 100 points equaling 1% C. What you have to know is the allowable range for each designation."

This statement is a bit of a simplification, but it is correct in that the last two (or three) numbers are referring to the nominal carbon content. There are additional requirements that are defined for the grade, but the numbers changes based upon the carbon content.

So yeah, I think there is some hair splitting going on, but it is worth noting that other elements do vary beyond the carbon with changing grades in the same "family" (10xx, 11xx, etc).

Per SAE J402, "SAE Numbering System for Wrought or Rolled Steel", the summarized description is:

"A four-numeral series is usually used to designate standard alloy and carbon steels specified to chemical composition ranges. There are certain types of alloy steels which are designated by five numerals. The prefix E is used to designate steels which are made by the basic electric furnace process with special practices. The suffix H is used to designate standard hardenability steels. The last two digits of the four-numeral series and the last 3 digits of the five-numeral series are intended to indicate the approximate mean of the carbon range. For example, in Grade 1035, 35 represents a carbon range of 0.32 to 0.38% and in grade E52100, 100 represents a carbon range of 0.98 to 1.10%. It is necessary, however, to deviate from this system and to interpolate numbers in the case of some carbon ranges, and for variations in manganese, sulfur, or other elements with the same carbon range. The first two digits of the SAE numeral series for the various grades of alloy and carbon steel are given in table 1".

[ThomasPowers]

Sure Hot rolled is a good choice for that use as it's generally cheaper and so you can use heavier stock without paying out the nose for it---easier to find it too.

We're just throwing mashed potatoes in the school lunchroom...

[Ten Hammers]

My shop, my needs. I can see NO need for me to use any cold rolled for any of my business ( exception being 3/16 square which I cannot source in hot).

Do I use cold ? Yes simply because it find it cheap or occasionally it is given to me. The corners on cold square are nice and sharp and from time to time it make a much nicer looking handle but in general, hot rolled is what I use. Some sources of hot rolled will have junk metal. My supplier doesn't get from them. Yes you will find some steel these days ( last 20 years indeed ) that is marginal when forged. The rest I will leave to the experts.