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Re: ASTM A36

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On Feb 3, 2006, at 5:44 AM, Mario Velez Nauer wrote:

We use in Brazil still a lot of steel plates/beams etc. made according to ASTM A36. 
What is the admissive minimum Carbon content of this material ?.
One of those questions where you've either said too little or too much.

A-36 has a maximum Carbon content, not a minimum. The maximum varies from 0.25% to 0.29% depending on thickness. Thicknesses over 1/4 inch also require a manganese content ranging between 0.8 and 1.2% and silicon between 0.15 and 0.3%. And there's a maximum phosphorus and sulfur content of 0.04% and 0.05% respectively. There are also some very important process and delivery requirements that are in the spec, which you should get immediately. This is information that you absolutely must have, and if you haven't memorized most of it you're going to end up in trouble.

If I were to guess, I'd say someone is trying to tell you that some steel is 'just the same' or 'probably' A-36 and you're looking at some chemistry to support the claim. You want to be very careful what you do with this stuff, particularly if you're going to weld it. If you really don't know what you have you need to find out by doing some metallurgical testing to find the mechanical properties, microstructure and chemistry. If you're going to weld it, you should make welding procedure test plates and test those, too.

I'm not criticizing, I'm telling you so you'll know. Just the fact that you don't know that the carbon specification is a maximum, not a minimum, is a red flag. With cranes especially you're subject to cyclic loading and unknown steel welded improperly is a recipe for fatigue failures. Get the stuff tested.

If I guessed wrong, I'm sorry for lecturing.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)

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