I picked up a bunch of this round stock "commercial quality (CQ)" steel from a local metal supplier. They don't know exactly what it's made up of, or rather a specific metal type (like W1 or 5160), but they know it's a mild steel.
Does anyone here know what qualifies as commerical quality mild steel, or more specifically what might be in it?

Thanks!

Common structural steel 0.25 per cent carbon. Mild steel is likely to be either C1018 for cold rolled or A36 for hot rolled steel.
Wilkinson Steel and Metals: Carbon / Mild Steel - Hot Rolled

"Commercial quality" steel: Wilkinson Steel and Metals: Carbon / Mild Steel - Hot Rolled

Never heard of steel being rated as comercial quality before, maybe they just mean it's cold rolled versus the more common hot rolled, the difference is in the way it is formed and cold rolled is more precise and consistant in it's measurements. Cold rolled has a shinier finish with no mill scale (the flakey looking surface)
Kind of odd a metal supplier not knowing what they have.

welder19

Never heard of steel being rated as comercial quality before,.....Kind of odd a metal supplier not knowing what they have. welder19

In my youth I worked in a jewelry store. They referred to the junky jewelry as being made of "jeweler's metal", that was just a way of making it sound better than calling it "pot metal", or zinc, or letting the customers know how junky it was.

Could "commercial quality" possibly be a similar sales pitch? :confused:

If you read the link I posted, yeah: it's basically random, mild steel crud.

I used to buy "forging quality" bar as opposed to "merchant quality" bar. Seems "commercial quality" might be the same as "merchant". Dunno for sure. Had nothing to do with chemistry, Was mostly about allowable seams and other surface defect.

It's hot-rolled, yes -- I asked for that because of the price difference. I'll mention A36 and see if that rings a bell for them.
Do you guys know of any pitfalls when forging A36?

Thanks for the great input so far :)

I believe A.I.S.I. (like 4140) is about chemistry, A.S.T.M. (like A-36) is physical properties (and loosely chem) and "quality" indicates acceptable surface condition.

A-36 is about as "mild" as we can ever get any more.

I believe A.I.S.I. (like 4140) is about chemistry, A.S.T.M. (like A-36) is physical properties (and loosely chem)

Yeah: A36 basically has to meet certain mechanical specs. Chemically, it can vary widely. Sometimes it's hardenable. Sometimes it's hard to weld.

O.K. It was "special quality" bar that I used to buy, sometimes called forging quality by forgers. I can only find "special" and "merchant" quality, I think they made up the "commercial" quality.

Here's one manufacturer's description of its commercial quality steel:

Description
Hot Rolled Commercial Quality Steel is ordinarily produced in a low carbon grade of steel. It is suitable for many applications where the presence of oxide and normal surface defects are not objectionable.

Hot rolled commercial quality is ordinarily produced from rimmed, capped, or semi-killed steel, at the producer’s option, with sufficient discard taken to remove visible piping. Because of the segregation inherent in the solidification of these types of steel, they do not have a high degree of uniformity in chemical composition and mechanical properties.

When a carbon content is not specified commercial quality is furnished to a maximum carbon limit of 0.15 per cent by ladle analysis.

The oxide on hot rolled commercial quality is subject to variations in thickness, adherence and color. Removal of the oxide will reveal surface defects not readily visible prior to this operation.

Sheets of this quality sometimes show imperfections after deformation which were not clearly visible on the sheet as produced. Such imperfections may be expected on hot rolled commercial quality sheets. Sheets of this quality should not contain piped steel.

Hot rolled commercial quality sheets are subject to coil breaks, stretcher strains and fluting in the hot rolled condition. This quality can be furnished with non-fluting properties when specified.

Hot rolled commercial quality should meet minimum bend test requirements. Bend test requirements do not apply to commercial quality sheets specified over 0.25 per cent carbon by ladle analysis. Hot rolled commercial quality is not subject to any other mechanical test requirements. If greater ductility than the minimum is indicated, the bend test is required, drawing quality should be specified.

If specific mechanical test values are required, physical quality should be specified.

Special killed steel, special soundness steel, normalizing, box annealing or other added processes or practices are additional requirements that are sometimes specified. Special surface requirements should be specified when applicable.

Sheets of this quality up to 0.15 per cent carbon maximum are frequently specified to ASTM A1011, Hot Rolled Carbon Steel Sheets, Commercial Quality. Sheets meeting the requirements of this specification are generally available as stock material.

who was the manufacturer, matt. sheeetmetal may have lower content than a36 due to the roll and die forming it undergoes so that it is more ductile

The link is in my first post in this thread.

Hey guys,
Thanks for the input so far. I just talked to the supplier and he confirmed it was CQ A36 steel, but since it was a batch of 1/4" rounds, they didn't do a specific chemistry test. He's going to send over some more details after they do do a chem test to find out what's in it.
Not a big deal because the steel is workable, but since it wasn't that expensive and they're local, it's nice to have a rough idea of what's inside the steel. :)

Here's the section of their test report that's relevant to my order. 0.20% carbon by the look of it. Works for me at the price point :p

Interesting cert. Also look at the "carbon equivalent" .35! Copper and manganese are a little high along with the others add to the carbon equivalent. A-36 requires 36,000 minimum yield and this is 58,000! But, it'll probably be fine. So it's A-36 commercial quality. I think that's the same thing as the old "merchant quality".

That's weird: the cert. says it's 1018.

1018 allows carbon of .15 - .20 and everything else is in line with 1018. I know that some folks buy cold drawn because they believe the 1018 is better than A-36. As you can see from this, they can be the same! A lot of cold drawn is just made from A-36 that didn't make the cut usually because it was rolled undersize. The cold drawers just pickle, lube and draw it through a die.

Edited October 30, 200916 yr by nakedanvil

I'm just surprised they'd use the "good stuff" for A36! ("Good" only in the sense that you know roughly what's in it, unlike the usual case with A36.)

There is very little difference between 1018 and A-36 (or none in most cases). Sometimes the carbon in A-36 will be lower. The higher yield is just from cold drawing, after forging they will be about the same:

1018 Mild Steel
Alloy 1018 is the most commonly available of the cold-drawn steels. It is generally available in round rod, square bar, and rectangle bar. It has a good combination of all of the typical traits of steel - strength, some ductility, and comparative ease of machining. Chemically, it is very similar to A36 Hot Rolled steel, but the cold drawing process creates a better surface finish and better properties.
1018 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 63,800
Yield Strength, psi 53,700
Elongation 15.0%
Rockwell Hardness B71
Chemistry Iron (Fe) 98.81 - 99.26%
Carbon © 0.15 - 0.20%
Manganese (Mn) 0.6 - 0.9%
Phosphorus (P) 0.04% max
Sulfur (S) 0.05% max

A36 Mild Steel
ASTM A36 steel is the most commonly available of the hot-rolled steels. It is generally available in round rod, square bar, rectangle bar, as well as steel shapes such as I-Beams, H-beams, angles, and channels. The hot roll process means that the surface on this steel will be somewhat rough. Note that its yield strength is also significantly less than 1018 - this means that it will bend much more quickly than will 1018. Finally, machining this material is noticeably more difficult than 1018 steel, but the cost is usually significantly lower.
ASTM A36 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 58,000 - 79,800
Yield Strength, psi 36,300
Elongation 20.0%
Chemistry Iron (Fe) 99%
Carbon © 0.18 - 0.26%
Manganese (Mn) 0.75%
Copper (Cu) 0.2%
Phosphorus (P) 0.04% max
Sulfur (S) 0.05% max

So, in other words, 1018 can be just as bad as A-36, only more expensive.

Thanks, Grant. You just dispelled a lot of misconceptions that I had about A36! Now I don't feel so bad about using it in stuff liked wrapped and welded hawks. (With a higher carbon bit, of course.) :)