Working temperatures of metal materials

The subject is far too complicated for a simple answer.

The heat treatment of steels is the subject of entire books. (Hardening, tempering,anealing, chemical/heat treatments)

Some metals act in exactly the opposite manner to others.

e.g. anealing copper is (I believe ) the opposite process to anealing steel.

Also what do you mean by safe?

Safe in terms of not effecting the properties of the metal...or safe in terms of risk to the worker?

(Every man is his own safety officer!)

Safe in regards to not affecting the material properties. I understand that most metals are different in this respect. I'm just needing to report on selected metals for certain work environments. I want to suggest the temperature range for them and I don't know where I can find this. I can only find melting points or heat treat temps.

Konichiwa, Neko desu.

Great answer Del.

The issue of mechanical properties change with microstructure is just one aspect to be concerned with. Scaling, decarburization, oxidation, the list goes on and on.

Also, whatdo we mean by work?

The question would probably be best worded, What condition would give me the optimum results for my (machining, drawing extruding, heading, etc. etc. ) process for the following materials?

then for each material and process, we could intelligently answer, Lamellar pearlitic anneal (4140 machining) spheoroidize anneal, aged, or any one of a host of thermal treatments, microstrutures. All done with assurance of proper atmosphere to eliminate possibility of decarb or loss of passivation...

milo

Hmmm, I agree with the last post, it's a little complicated.

It all depends on which metal /a lloy are you using and the treatment it had before you start using it.

If a metal and alloy doesn't have any heat treatment, it could be considered safe to use it at a temperature 80 °C below the phase change line.

You will ALWAYS need information from the phase diagram of any metal/alloy you intend to use.

For example, steels are alloys of iron and carbon, everybody knows that, but how much carbon is the difference. It is quite simple to know the phase change temperature using an Ir-C phase diagram. You only need to look in a vertical line over the composition your steel has, and that vertical line will cross with the phase change lines as you rise the temperature.

There are other factors you have to consider, for example Aluminium hardens by a process called "age hardening" which is opposite from steel tempering.

But before I start to mess everything up, why don't you post which kind of metals or alloys you want to use or have to use.

But remember, you need its particular PHASE DIAGRAM and the conditions of the material (structure, and treatment) before you do anything.

Lets try these for now. Steels in the annealed condition and aluminums as called out.

Ti-6Al-4V, AISI 440C Stainless, 17-4PH Stainless, AISI 304 Stainless, AISI 316 Stainless, AISI 4130 Steel, AISI 4140 Steel, 2024-T3 Alum., 6061-T6 T651 Alum., 7075-T6 T651 Alum.

You may refer to ASME Standards to find Allowable stress values at different temperatures for all the commonly used metals & alloys in industries.

ASME Section II and ASME B31. 3 etc.

Hetti

I think the biggest problem with high T for metals is creep; in order to limit diffusion, T should be about 0.3 Tmelting. You can find a simple basic discussion of these topics in M. F. Ashby and D. R. H. Jones, Engineering Materials I (2nd edd.) Butterworth Heinemann, (2000)

Your question express "why we use codes & standards"?

According to Stress-Strain curve, the yield strength of any material depends upon the test temperature. So at any temp., there is an allowable tensile strength to be applied at design equations.

At ASME codes for pressure vessels (ASME BPVC, Sec. II, Part D) and piping (ASME B31.1, B31.3, B31.4 & B31.8) there are a Tables including a full data for the allowable tensile strength at each specified temp., max. temp. limits, min. tensile strength & min. yield strength.

If you have an ASME or ASTM material you can tell me and I can give you what you want.

Best way is to refer to the phase diagram.

It will show you the various phase changes with rising temperature.

Also, look at chemistry to determine austentic phase of lowest point melting temp elements. This is when properties begin to change with rise in temperature.

there should be a full heat cert available for material lots and a specification indicating service temperature range.

this will take research on your part to determine application and suitability.

what is your application?

Thanks everyone. I was able to find www.matweb.com where I can find material specs and use interactive graphs. Cool sight! Check it out. Great information!

THANKS AGAIN!