steel hardness/quality codes

[bushwacker]

Can any one enlighten me a little on a couple of things please.

1. What is the code for mild steel in it's softest form please. I would like a list if possible of the codes and a bit of a description or properties of other steels please, but the main thing is the mild steel. Please be patient with me as I'm not that good at explaining my self in print.


I think that the codes would be the same in the U.S. as here in England, as we have common goals for near enough every thing else.

2. I have read somewhere something entitled 3 wire measuring of threads (I think it's three wire) what is it please.

Thanks every-one.

 

[DMS]

I am not familiar with the codes you are asking about in your first question, but for you second question, the 3 wire method is used to measure thread diameter. If you have a copy of the Machinist's Handbook, I believe there are a couple pages in there about it.

 

[Ray C]

For mild carbon steel, the numbering system is defined by the AISI/SAE organizations. An example is something like 1018. The first digit says it's carbon-based, second digit indicates 0=no alloy, next 2 digits (18) inicate .18% carbon. (This does not apply to stainless or aluminum. There are different codes for those).

Now that doesn't answer your question because you want to know about hardness. To talk about hardness, you have define the state of the metal because metals can be "normalized", or "annealed" to some level of "temper" for the purpose of "heat treating".

To answer your question in a techncial way, any metal in it's softest form is said to be "fully normalized" and possibly "annealed". In it's softest state, metal can be tested on various hardness scales (Rockwell A, B, C etc and Brinell are very common). I don't know the exact number but I think 1018 in softest state is about 35 or 40 Rockwell.


Ray

EDIT: To find-out the harndess ratings of different metals, to just about any steel supplier and lookup the characteristics of the metals they sell.

 

[bushwacker]

Sorry for the delay in replying, I have as suggested looked in machinerys handbook for the wire measuring question that I asked and got a good idea of what it is, thank you.

I looked in several books that I have and got the answer to the other question too. It comes under material groups in a swiss tech reference book that I didn't give a thought too, but there it is on page 14, the info that I was looking for.

I don't know if it is available in the U.S. or not, but here in England it is from Cromwell Tools, and entitled The Pocket Ref.

Thanks again guys for your help.


Phillip.