Mild Steel Spec

^ · Post by ^ » Wed Jun 03, 2009 9:51 pm

Does anyone know the specific type of steel they get one they are buying mild steel?
1008? 1018? A-366? A36?

Konstantin the Red · Post by **Konstantin the Red** » Wed Jun 03, 2009 11:04 pm

A look in the back pages of Machinery's Handbook's Shop Handbook for Students and Apprentices gives a rundown on mild steels.

SAE 1006, 1008, 1010, 1015: readily welded, watch for embrittlement in forming and grain growth, not suitable for machining into screws and such, modest strength

SAE Steels 1016 through 1030 in whole numbers: gradually increasing carbon content until the low range of medium-carbon, greater strength, not as cooperative to cold form, better stuff for screws and bolts and machined components generally, sees use for case-hardened components.

raito · Post by **raito** » Wed Jun 03, 2009 11:58 pm

I only know when I order something specific. Otherwise, I assume it's recycled material of dubious composition.

Baron Alcyoneus · Post by **Baron Alcyoneus** » Thu Jun 04, 2009 5:52 am

1018 is common.

Sean Powell · Post by **Sean Powell** » Thu Jun 04, 2009 8:09 am

Anywhere from 1030 down to A36 and worse. If you don't buy it to a spec it can be anything... Not as bad as re-bar though. That is iron or steel of some alloy. We got a batch for tent-stakes that was high enough in carbon to make a decent knife and could have made an ok file!

Sean

^ · Post by ^ » Thu Jun 04, 2009 9:28 am

I know what the different steels are, I am trying to figure out what people are actually buying for those that know.

Thomas Powers · Post by **Thomas Powers** » Thu Jun 04, 2009 11:00 am

If you walk into a steel distributor and say "gimmie a 14 guage mild steel sheet" you most likely get A36---which is not anything like what you got 50 years ago when you did the same thing.

What the handbook says has little to do with what you get. *unless* you go in and ask for 1018 or 1020 sheet and then be prepared to pay a whole lot more!
(and better test it too as somewhere along the line A36 may have been substituted!)

Just like machinerys handbook says that S-7 is a good steel fior jackhammer bits. it is indeed and a fellow blacksmith who spent 30 years re-pointing jackhammer bits (as in a cool million of them!) has seen nearly a dozen that were S7 rather than 1050.

It used to be that CR steel was generally a true mild steel but CR A36 is showing up nowdays.

Thomas

Sean Powell · Post by **Sean Powell** » Thu Jun 04, 2009 12:58 pm

(for those people not following everything 1018 etc is a designation for the carbon composition while ASTM-A36 is a specification for minimum mechanical properties. Either acts as a control but most metalurgists like to think in recipies while most structural engineers don't care if it's laminated monkey-shit, so long as it's strong enough)

It may vary by location but my experience leads me to believe that most of the steel fabricators and sheet-metal rollers want to get the most bang for the buck. The bigest effect on cost is labor and A-36 dosn't roll any faster then 10-18. Seeing as how 1018, 1015, 1012, 1008 and many other compositions can be later re-sold as A-36, they don't actually make A36. A36 is the left-overs, factory seconds and things that just don't run perfectly. It is much more profitible to make and sell 1018, etc.

The key is very few of us order in sufficient volume to deal with the manufacturers. Retailers on the other hand want to buy the cheapest stuff they can and sell it as high as they can. This means they buy the factory seconds, chop it into smaller pieces or smaller lots and distribute it where-ever regardless of the actual composition.

Foundaries that are making I-beams however get actual requests for A-36 so it is profitible for them to produce the cheapest possible thing the customer will accept. Even so most I-beams are better then A-36 since A-36 only specifies a MINIMUM yield, and some times it pays to be comfortably higher so dips in quality don't mean sudden spikes in scrap production.

Still, if you can't guarente something is better then A-36 (or even up to A-36) don't go assuming that the next piece will be just as strong as the last one. If you don't order to a specific designation or spec, what you have is a shot in the dark.

Sean

^ · Post by ^ » Thu Jun 04, 2009 2:11 pm

Are yall sure yall aren't talking about both A36 and A366 together.
Everything I have found puts the carbon content of A36 steels in the .2x% range but hot rolled vs 1018 which apparently is cold rolled making it harder off the bat.
With A366 being somewhat synonymous with 1008 although it would apear A366 isn't a term much used anymore.

Sean Powell · Post by **Sean Powell** » Thu Jun 04, 2009 3:55 pm

Piers Brent wrote:Are yall sure yall aren't talking about both A36 and A366 together.
Everything I have found puts the carbon content of A36 steels in the .2x% range but hot rolled vs 1018 which apparently is cold rolled making it harder off the bat.
With A366 being somewhat synonymous with 1008 although it would apear A366 isn't a term much used anymore.

Well I'm a Mech-E not a Struct-E so I'm a little out of my element and it's been a few years since I've worked in that industry but...
Marks Standard handbook for Mechanical Engineers,

Page 6-27:
ASTM-A36 Yield 36ksi, Tensile 58-80ksi, 20% Elongation.

Page 6-28:
[A36] ...was developed to fill the need for higher-strength structural carbon steel then the steels formerly covered by ASTM A7 and A373 (I see nothing about A366. I'll see if I can't pull the spec from our library)

Page 6-35:
Average Mechanical Properties of some cold-drawn steel
1010 Yield 55.0ksi, Tensile 67ksi, 25% Elongation
1015 Yield 60.3ksi, Tensile 71ksi, 22% Elongation
1020 Yield 63.7ksi, Tensile 75ksi, 20% Elongation
1025 Yield 68.0ksi, Tensile 80ksi, 18.5% Elongation
1030 Yield 73.9ksi, Tensile 87ksi, 17.5% Elongation

It's difficult to compare a min standard to an average test value and it's quite possible that some samples of A-36 happen to be stronger then 1010 but odds are it's not nearly as good. There is also a pretty steep climb in strength between 1010 and 1030 and those are all 'mild' steels.

'Deep Drawing' steel is also technicly mild and while I don't have strength numbers for it, it's rather soft and likes to stretch.

The term 'Mild Steel' is just way to vague to apply numbers to. It could be almost anything.

Sean

^ · Post by ^ » Thu Jun 04, 2009 4:26 pm

Sean Powell wrote:
Page 6-35:
Average Mechanical Properties of some cold-drawn steel
1010 Yield 55.0ksi, Tensile 67ksi, 25% Elongation
1015 Yield 60.3ksi, Tensile 71ksi, 22% Elongation
1020 Yield 63.7ksi, Tensile 75ksi, 20% Elongation
1025 Yield 68.0ksi, Tensile 80ksi, 18.5% Elongation
1030 Yield 73.9ksi, Tensile 87ksi, 17.5% Elongation

It's difficult to compare a min standard to an average test value and it's quite possible that some samples of A-36 happen to be stronger then 1010 but odds are it's not nearly as good. There is also a pretty steep climb in strength between 1010 and 1030 and those are all 'mild' steels.

Based on what I've been finding is that A36 is hot rolled, those numbers are cold drawn.
Here are some of the sites I've been looking at, although it is mostly moot as the local place doesn't carry anything thinner then 16ga in it.
http://www.onlinemetals.com/steelguide.cfm
http://www.a36steelplate.com/
And the local guy said its ~.25% carbon.
Interestingly enough some hot dipped galvanized has a higher carbon count.
The reason I care about the carbon count is because I'm interested in playing with superquench and sheet steel and 1008 isn't cutting it.

Signo · Post by **Signo** » Thu Jun 04, 2009 4:54 pm

You are lucky to have to choose which material to use. Here despite the fact that there are many factory that work coils and sell steel sheets, all I can have is mild steel, zync coated mild steel, stainless steel. Sto Oh yes, I can choose from "black" and "white" (rough from the mill or washed with acid). Often I cannot choose, I ask black and they sell me white because is all that they have (obviously I pay it as black).
Depots many thousands of square meters, and not a sliver of carbon steel in form of sheet (unless I don't want to make armour with 8 mm plates). :oops:

Sean Powell · Post by **Sean Powell** » Thu Jun 04, 2009 5:51 pm

Piers Brent wrote:Here are some of the sites I've been looking at, although it is mostly moot as the local place doesn't carry anything thinner then 16ga in it.
http://www.onlinemetals.com/steelguide.cfm
http://www.a36steelplate.com/
And the local guy said its ~.25% carbon.
Interestingly enough some hot dipped galvanized has a higher carbon count.
The reason I care about the carbon count is because I'm interested in playing with superquench and sheet steel and 1008 isn't cutting it.

Ahh ok, now we have a purpose. You are trying to harden 'mild cold drawn' steel with super-quench rather then case-hardening or similar. That's a cool idea... but why buy unlabeled mild steel for this experiment? It's just as easy to get 1018 or 1020 specificly by asking for it. If you do and get good results you will know what you started with and the results will be repeatable. If you start with an unknown quantity, even if you get a good result, you won't necessarily be able to duplicate it without getting lucky again? Generic Mild steel is too variable of a product to be certain of getting the same carbon content from different deliveries.

BTW, if you want to test it with say 4" x 1/2" strips you can send a few to me and I can bring them down to the lab and maybe get a surface hardness reading as well as a tensile test or maybe a 3-point bend test to see if you are getting the mechanical properties that you want.

Sean

^ · Post by ^ » Thu Jun 04, 2009 7:42 pm

Sean Powell wrote:
Ahh ok, now we have a purpose. You are trying to harden 'mild cold drawn' steel with super-quench rather then case-hardening or similar. That's a cool idea... but why buy unlabeled mild steel for this experiment? It's just as easy to get 1018 or 1020 specificly by asking for it. If you do and get good results you will know what you started with and the results will be repeatable.

While I can order anything that partially defeats my purpose, which is to have a steel reasonably readily available locally that will work. I have some 4130 in my shed and can order whatever but I want readily commercially locally availible. Looks like it likely won't happen unless oddly enough its galvanized.

Signo, here if you want something specific you tend to have to order it from specialty places.

Sean Powell · Post by **Sean Powell** » Fri Jun 05, 2009 7:31 am

Piers Brent wrote:While I can order anything that partially defeats my purpose, which is to have a steel reasonably readily available locally that will work. I have some 4130 in my shed and can order whatever but I want readily commercially locally availible. Looks like it likely won't happen unless oddly enough its galvanized.

I had a thought on the drive in to work this morning. If you have metal you already own and you are confident all of it came from the same lot, you can clip of a corner (maybe 1" square or equivilent) strip any pickling agent off and mail it to me. I'll bring it to the plant and zap it with the Niton gun to get an exact chemical breakdown for you including %carbon. They you will know exactly what you have.

I just can't guarente that the next sheet you buy from the same supplier will be the same since he can buy and sell a whole range of choices and still be selling 'mild' steel.

Keep us posted, this superquench stuff looks interesting but I'm more familiar with case-hardening or kolsterizing to achieve the same process.

Sean

^ · Post by ^ » Sat Jun 06, 2009 12:05 pm

Signo, ask for the specifications on the steels they carry. Hopefully they have a consistent supplier and you might be surprised by what you get.

The local place I have been talking to doesn't sell anything and just call it mild steel. They carry 1008, A36, and A653 which all seem to have reasonably set standards. 1008 is what they sell as cold rolled. A36 up to 16gauge is sold as hot rolled. And A653 is basically A36 that has been hot dipped galvanized. They have it in 18 and 24 gauge. While it would obviously need to be tested A36 should heat treat with super quench and A653 should as well but you'd have to strip the galvanization first or should.

Sean I don't suppose you have access to a piece you know was made from 16 gauge hot rolled steel purchased as a full sheet from a dealer. I would love to see the carbon content of that as it may be that A36 is what is commonly sold as hot rolled mild steel. Wouldn't it be ironic if over the years people held cold rolled to be better because of its off the rack properties but it may very well be that the hot rolled has more carbon and therefore might be heat treatable.

Sean Powell · Post by **Sean Powell** » Sat Jun 06, 2009 8:16 pm

Piers Brent wrote:Sean I don't suppose you have access to a piece you know was made from 16 gauge hot rolled steel purchased as a full sheet from a dealer. I would love to see the carbon content of that as it may be that A36 is what is commonly sold as hot rolled mild steel. Wouldn't it be ironic if over the years people held cold rolled to be better because of its off the rack properties but it may very well be that the hot rolled has more carbon and therefore might be heat treatable.

Sorry I haven't spec'ed anything in A-36 in several years and most of that was I-beams. I'm ordering a bunch of stuff from McMaster-Carr on Monday. I'll see if they have any cheap hot-rolled sheet A-36.

Sean