The Home Machinist!

Or more specifically, steel specs as provided by suppliers. As I'm still new to machining, I buy metal in small quantities, and my primary supplier is Online Metals. They have a product guide on the stuff they sell that includes mechanical properties and chemical specs. So here's the question(s).

Using 4130 normalized steel as an example, the spec says ultimate tensile strength is 97,200 psi, yield strength is 63,100. Are these the numbers of the material I'm buying, or are these the numbers AFTER heat treating? My understanding is that normalizing IS heat treating, but I'm not sure, so I'm asking. I'd rather look stupid than BE stupid and have something blow up in my face . Thanks, gents.

Dave

Annealed 4130 1" bar: http://www.matweb.com/search/DataSheet. ... 5b1b2b6259

Normalized 4130 1" bar: http://www.matweb.com/search/DataSheet. ... aa9f0312fb

Different process, different results.

The spec should be for the state that the material is claimed to be in as purchased.

Not real sure, but I believe one is a controlled cool over a relatively long period of time after heating to a specified temp, and the other is removed from the furnace and cooled at room temp.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

normalizing is a process where steel is heated up to a temperature lower than the annealing temperature. Basicaly normalizing is getting steel ready to be heat treated. Although it is heat, and it is treating the steel, it would not normaly be considered to be "heat treated steel".

when you say blow up in your face, i hope that is figurative because i do not think that 4130 would be proper steel for a gun barrel. Maybe for black powder but not smokeless. I may be wrong.

I don't know where companies like Online Metals or Speedy get their metals from. If metal specifications are a concern, you need to get metal that is certified to meet your specification.

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Mr Ron, Almost as smart as the average bear.

Excellent advice, except for the fact that it lacks any indication of where the home machinist might obtain "metal that is certified".

Suppliers generally receive chemical analysis from the maker, so they simply photo-copy the analysis. The analysis report is tied to the material via a heat number. You are at the mercy of the supply house ----they may or may not offer the service, and they may, or may not, keep the material organized such that it can be related to the certs in question. I expect that any supplier with a respectable reputation would comply, however, as certified materials are often required.

I was required to provide certs for everything defense related when I machined---all processes included (heat treat, finishing, and any other operations that may be required). Instead of submitting multiple copies of certification, I provided a blanket certification indicating that all requirements were observed, and that certification was on file if requested. That served the purpose adequately. I was never asked to provide further evidence of compliance.

Harold

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Wise people talk because they have something to say. Fools talk because they have to say something.

I have dealt with Online Metals and have received material certs with the shipment when I requested them. On my end I stamp identifying nomenclature on the material tying it to the particular cert sheet.

There was recently an interesting thread on PM regarding how far one should go to verify that the material and the certs actually match. Always that question.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!