Would an OES and hardness test be sufficient?

[Zeyneb]

I need to determine if a unknown steel sample has received a heat treatment or not. So I'm advised by someone on another forum to have a laboratory perform an chemical composition analysis. I do think an Optical Emission Spectrometer (OES) analysis would be the most suitable because it is important to have the carbon content as well. Still it does not tell anything about the hardness and relating to that the tensile strength. So I assume I do need to add a hardness test also. Rockwell maybe.

What I'm wondering about is if the material composition and the hardness will tell me everything I need to know to purchase the right steel and possibly do a heat treatment on it.

Could it be for example that the part has gone a sloppy quenching process without tempering and still reach the same hardness as a part with proper quenching and tempering. So the mechanical properties of the parts would differ?

 

[EdStainless]

Once you know the material then you can decide if a simple hardness will work or if you really need tensile and micro.
For many steels there are three or four ways to reach similar hardness with very different properties (elongation, toughness ...).
While the UTS correlates with hardness fairly well for steels nothing else does.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Zeyneb]

Thanks Ed! Much appreciated.

With that last bit "nothing else does." You mean the other properties like elongation and toughness, do you?

 

[EdStainless]

Yes. You might have the UTS but yield, elong, toughness, and who knows what else may all be different.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Dhurjati Sen]

You ought to have a requirement, a standard or a benchmark for comparison. Even if the unknown steel sample has received a heat treatment, still you need to know what exact heat treatment has it received.

DHURJATI SEN
Kolkata, India

 

[Zeyneb]

I'm also very much interested in this. What should I be able expect from a laboratory. Would a proper OES be able to specify all the elements in the steel to two decimal places? Also carbon and sulfur. Weight percentages are the usual specification, do they? What is shown at McMaster-Carr product pages for steel types are also weight percentages, right?

 

[EdStainless]

OK, so that give you the chemistry.
In most cases there will be a few steel specs that that chemistry meets.
Now how about condition.
Is it annealed, normalized, N&T, Q&T, at what temper temperature, was it quenched correctly, and such questions.
To answer these questions you need good micros and full properties.
Approaching this backwards like you are takes a lot of work.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

zeyneb
send out a cut sample to a metlab, and request a full spectral analysis for chemical, heat treat condition, hardness, and grain structures, have them identify the material.

 

[Zeyneb]

Hi mfgenggear,

What should that cost me approximately? I'm an automotive hobbyist from Europe. Sample #1 is round rod with diameter of 18mm and length of 30mm. Sample #2 is round tube OD 25.4mm and wall thickness of 2.7mm and length of 73mm. I don't care about coating I will grind that off before I ship the samples.

 

[mfgenggear]

zeyneb

in that case it would be cheaper to buy a minimum lenGth and heat treated by a supplier.
send out for quotes , it can vary from every supplier for metlab. but could be between $800-$1000 dollaRS

 

[Zeyneb]

Sorry I don't know what you mean. You mean abandon the chemical analysis altogether?

What is meant by "buy a minimum length" for example?

 

[mfgenggear]

Zeyneb
Buy a minimum length in material from a steel supplier, it would be cheaper than a metlab.
quote it both ways. the heat treat will depend on the hardness required, and the configuration of the part and it's complexity

 

[mfgenggear]

request a material certification. look at standard specifications and what is available at the steel supplier

 

[Zeyneb]

It is for a critical car part. I don't want to risk making assumptions about the steel. I do believe EdStainless is right in his advice to me.

Furthermore I don't like you being so terse in your communication. Was that $800-$1000 estimate what it could cost me for a full analysis of these two samples at metlab?

 

[mfgenggear]

zeyneb

maybe your question needed to be less terse. this is what you get for free . my answers were simple and short, problen is you are naive.

 

[mrfailure]

Hi Zeyneb, Since you say the material is unknown you should make sure the chemistry testing will tell you elements to confirm if you have an alloy or carbon steel. The commercial testing lab I worked at had a standard suite of elements being tested for in steel that included C, Mn, P, S, Cr, Mo, Si, and Si. Phosphorus and Sulfur are reported to 3 digits, everything else to 2 digits. I prefer and request 3 digit reporting for carbon if it measures below 0.08% (this can affect welding parameters). The lab may use a carbon/sulfur analyzer for those elements instead of OES depending on what they get. Costs for simple chemistries like this are considerably less than what is discussed above but you local lab will be able to quote you a standard price before you proceed.

 

[Zeyneb]

Hi mrfailure,

Thanks. I responded back to an Italian laboratory just now. Providing some more information to them for a quote.

For #1, the panhard mounting point, I'm tempted to bet on 4130 as a replacement to save cost. I've asked them if they can check if sample #1 has received a heat treatment and if so, which one.