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ASTM A36 Steel

Gordon Coor

Aluminum
Joined
Oct 21, 2003
Location
Long Island, NY
Could someone explain to me what ASTM A36 Steel is. As a novice home shop guy, I'm already fammilliar with the AISI/SAE steel numbering system.

In my professional life, I often see ASTM A36 steel specified in drawings, etc. Since my boss thinks I'm an engineer, I figure I'd better know what this stuff is in case he asks me some day.

Are these ASTM designations simply specifications covering tensile strength, yeild strenth, etc., that a number of the AISI steels would meet?

Thanks,

Gordon Coor
 
It's just like the plate form of 1018 mild steel. Cuts like butter. The scale on the outside is nasty though. Gring, or acid etch off the scale. It will eat your tools.
36k psi tensile/yeild.
 
Gordon,

ASTM A36 designation is usually applied to structural steel. This steel in the "as rolled" condition will have a minimum 36KSI yield strength and between 58-80 KSI tensile strength. Many people think that just because you have the 36KSI yield, you meet A36 specs. The max of 80 KSI tensile is there so that the structural member is no so brittle as to cause cracking.

Most (but not all) structural pieces such as angles, channels, and beams are made to A36.

JR
 
Doug,

A36 is not "just like 1018"!

First of all, the plate is in the "as rolled" condition (hot rolled). Second, 1018 hot rolled only has a yield of 32KSI.

You can not substitute cold rolled plate for A36! It is speced that way for a reason. It might machine similar, but its not.

I don't remember the exact details, but a few years ago, there was a large lawsuit against a shop that suppied re-enforcing cages for a bridge. The shop had substituted for A36 and the parts were cracking. Some of the concrete had already been poured and had to be removed. It was a nasty mess by the time it was straightened out.

JR
 
Sorry JRIwoa, I did not read the post right... I read how does it machine...I answered accordingly. It does machine soft as butter though, as compared to 4140.
 
A36 is designated as a "minimum" of 36K tensile strength. It's typically 60-65K. It's not really like 1018 because that steel is cold drawn, with a controlled carbon content. The price will reflect what I'm talking about here. Yes, they machine similarly, but they're not interchangeable.

Another thing is 1018, while weldable, usually you're better off to weld on if you preheat it. I've always just went right at A36 with the rods though.
smile.gif


A36 could have been anything from a leaf spring out of a car to a ball bearing to whatever in its former life, and sometimes retains undesirable properties from its former days!

Does anyone know if the max tensile strength recognized as A36 is 80K or 100K for sure? I can't remember.

Richard
 
My steel books call it out as 58/80,000.

I work with quite a bit of A-36 plate, generally 1/4" thick.
It will vary from lot to lot as to how well it blanks/punches.

The plain old 1/4" hot rolled just gives me fits. Like Richard says, you just don't know what got put in the mix.
I can't tell if it is too many Chevys or too many Yugos that screw it up.

I think the biggest difference is that they used to hold the contents pretty middle of the road and the material was fairly consistent.
Now I think they don't care if they hit maximum or minimum on the contents. I have plates from the same lot act differently.

I can be cruising along blanking out 1/4" thick 6" diameter circle blanks and the press and tooling is just singing a sweet thump, thump, thump tune.
Then I'll get a piece that makes it go bang, bang, bam, bam.
Then I have to worry about tonnage requirements and tooling damage.

The other side of it is that some of the stuff that blanks nice punches like crap.
I get nasty breakaways and burrs on large ID's and it just wants to hang onto the punch and not strip. Grrrrrr.

The mill scale seems to be worse on this crap also. It will flake and pop off and get all over everything. It is also very abrasive to my press tooling. It will dull punches and dies rather quickly.

Oh I miss the good old days of beautiful shiny blue hot rolled where you didn't even notice the mill scale.

I much prefer to run hot rolled pickled and oiled so I don't have to worry about the mill scale.

I have tried to talk one of my large customers into using HRP&O instead of HR and he says no. He claims the HRP&O doesn't galvanize as well.
Well, the first thing that happens to his parts at the galvanizing place is that they pickle the parts to remove the mill scale!

Oh well, life goes on.

Les
 
From the "Manual of Sreel Construction" 8th ed.,Table 2, P 5-73

Fy (minimum yield stress) 36 ksi
Fu (tensile stress) 58-80 ksi

Allowable-
Tension 30 ksi (0.5 Fu)
Bearing 87 ksi (1.5 Fu)

Allowable for bolted or threaded part
Tension 19.1 ksi (0.33 Fu)
Shear 9.9 ksi (0.17Fu) - threads not excluded
Shear 12.8 ksi (0.22Fu) - threads excluded
 
Thanks for all the information. Sounds like the bottom line is that the A36 designation represents a set of requirements for a structural steel. These requirements are based on tensile, yeild, and shear strenth, etc., but not on composition.

Thanks again,

Gord
 
Having worked in my blacksmith shop for over 20 years, I remember when A-36 started replacing 1018 as the "standard" material carried by most steel yards. I noticed early on that it had some really strange hot working and hardening properties.........so I went straight to the sources, and called a few of the steel companies. In a nutshell, A-36 Hot roll is created from all the left overs in the crucible(s). Let's say you ordered 22,000 lbs of 4140. The steel company will pour your batch and roll it, whatever is left in the crubile is added to other left overs, poured, rolled, and you have A-36. The problem with this stuff is that you never know what your getting. It can contain just about anything you could find in a scrap yard....... from tin to titanium, and everything in between. If you doubt it, try a quench test on a piece. Take a 1" X 1/4" piece and heat it to critical temp, then quench it in water. You'll see hard and soft areas throughout the piece. and in some cases I have even seen shapes that approximate screws, bolts, and such. Most of us in the bladesmithing world just call it "junk" steel.

[This message has been edited by Ed Caffrey (edited 01-09-2004).]
 
designation

'Designation' is the AISI, SAE or UNS number that designates the chemical composition of the steel. 'Specification' is the document, such as provided by ASTM, that specifies how to produce the material, how to run the processes. So A-36 will tell you how and it will tell you material properties, but it will not tell you what. Most steel is known by its designation as well as its specification, but not the very commonly used low-carbon structural steel that is usually known only by it's specification, ASTM A-36.

Now the question you may have is, what is the designation for a material to which A-36 is applied?

I do not remember. I came to this forum hoping to look it up again. ;)
 
Is 1020 hot roll similar or the same as A-36 ???

Not really Frank. Although it might machine about the same, 1020 is produced to "merchant quality" specs. I think that indicates the allowable range of elements is pretty wide, and I'm fairly sure there isn't any minimum strength requirement.

OTOH, I'd say there's a lot of overlap between what might be called A36 or 1020 when the stuff is coming from mini-mills that aren't known for controlling what's in the product very well at all.

1020 is the common spec on small angle, channel, flats, tees, etc. The larger sizes will be A36. If you see something that says "bar channel" or "bar angle" that normally means its made to the merchant quality spec. Not sure where the merchant term comes from. Maybe the hardware store :D
 
1020 and A36 are oranges and fruit.

1020 is an alloy composition, while A36 is a strength specification. 1020 material probably satisfies the A36 requirements. But not everything that satisfies the A36 requirements is 1020 material.

A36 is a very old specification. More recent ASTM specs (A572 and A992 leap to mind) put more control over chemical composition, while remaining focused on mechanical properties.

One of the issues with A36 is that over the last 30 to 40 years, material certified to meet A36 has been made with an increasing proportion of scrap material. This has caused material certified to A36 on average to become stronger over time. (And I am not talking about hard spots in particular pieces of steel bar.)

However, the A36 does not guarantee the greater strength. A572 Grade 50 (and now A992) are very popular specifications for somewhat stronger material (minimum 50KSI yield strength instead of 36KSI). Many mills can dual-certify their product for both A36 and A572 Grade 50. However, A572 does place some constraints on chemical composition that are not required by A36, so "stronger A36" material doesn't necessarily meet the A572 spec.

A couple of other things that might be of interest: Several of these specs put maximum limits on strength as well as minimum limits. This is because modern structural engineering exploits columns being stronger than beams (for example) and needs material certified to be no-stronger-than as well as at-least-as-strong-as. Also, the structural steel specs usually require good weldability through the use of "Carbon Equivalents". The actual carbon plus alloying elements must be as weldable as plain steel with a specified maximum amount of carbon.
 
Here is a quicker for you guys.

You have a simple profile with a few curves and holes and slots

Would you rather have them plasma cut or put them on the CNC mill?
 
The answer depends on...the necessary accuracy of the part as well as the available plasma technology. There are entry level air plasma cnc machines...and there are industrial high definition plasma systems that can cut with very nice accuracy. Attached are some parts that I cut with my low cost air plasma/cnc machine. All holes are plasma cut....some holes required tapping....they were cut with plasma ndersized...then drilled with a cobalt drill...then tapped.

The third picture is a part cut from 1/4" (hot rolled) steel...it is a tab and slot design that minimizes weld fixturing. These parts are as cut with an air plasma...and the part with the two square slots takes about 24 seconds to cut.....and the actual cutting cost (plasma operating cost...power, air consumption, consumables) is less than 15 cents.


Jim Colt Hyperherm



Here is a quicker for you guys.

You have a simple profile with a few curves and holes and slots

Would you rather have them plasma cut or put them on the CNC mill?
 

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Along with what sfriedburg said, a knowlegable steel supplier once told me the only thing he would feel comfortable about gauranteeing A36 plate is that is would sink if you threw it in the ocean. With as much scrap as is being recycled, no telling what you will find.
 
ASTM A36 steel is one of the most widely used carbon structural steels, it has good weldability, and usually hot rolled into rectangle steel, square steel, round steel, steel plate, and is also commonly made into all kinds of steel sections such as H beam, I beam, U channel, steel angle, steel tube, etc.
 
ASTM A36 steel is one of the most widely used carbon structural steels, it has good weldability, and usually hot rolled into rectangle steel, square steel, round steel, steel plate, and is also commonly made into all kinds of steel sections such as H beam, I beam, U channel, steel angle, steel tube, etc.

and I'm sure the next structure to collapse will involve lots of poorly made Chinese A36
 








 
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