How to tell 201 grade stainless steel from 304 grade stainless steel

You could try one of those portable hardness testers. Though that would need for some researching & also quite a bit pretty green papers

Good effort Milo.

I use to be a Tool Maker before I got sick of working for a living and became an engineer.

Telling the difference between different steels by spark testing is relatively easy if you have known samples to compare to.

The amount of carbon in 201 and 304 SS is potential to close to call.

As you have said the major difference is the percentage of manganese and this would be picked up by spectrum analysis.

I would not have thought the the difference in scrap value between the two would justify the time, effort or expense of sorting to that degree of accuracy.

BAB.

You said

"I use to be a Tool Maker before I got sick of working for a living and became an engineer."

So it was the hours that you objected to? Engineering work is fun, but so is tool making. Unless of course, the management upstairs has no idea what they're doing and always come to you at the last minute to bail their sorry butts out...

On second thought, never mind.

"Telling the difference between different steels by spark testing is relatively easy if you have known samples to compare to."

I couldn't agree more.

I had my maintenance department weld together "xylophones" that we had located in rough shed , production line start positions, at the scale, and in shipping. Also made "Key rings" with the samples (Big honkin medieval key rings if you know what I mean.)

The trick was when we'd get a new grade in on an order, we'd take one bar, send out a matchmark sample to lab to confirm, and then cut it into 6-8" pieces, steel stamp an ID numberon all pieces, and cross drill a hole through it so they could be put on a ring or wire. When we'd plan to do a sparktest sort, we'd look at the cert, and then identify the proper sample(s) to use as confirmers. (We trained our guys to look at spark characteristics by element, not just match the spark identically, so we could look for say nickel swellings on the carrier stream between the bursts, or moly arrowheads detached from the end of the carrier line.) Or sulfur, silicon, etc. But If the steel had been screwed up in heat treat (decarburised) all bets were off...)

We tied valiantly to make sure each different sample was a different diameter or shape too.

Spark testing as a comparator is the best usage if you aren't doing it every day.

Thanks for the feedback.

milo

If you are doing a lot of this, you may want to look into portable X-Ray fluorescence analyzers.

Tad

A quick and easy way is magnetism. I beleive that you will find that the 200 series SS has a magnetic draw as oppossed to the 300 series that doesn't.

300 series are magnetic. Not stronge but still magnetic. Cold worked 303 will be picked up by a magnet. I didn't believe it but I had it in my hand.

I work in a stamping company, and we sort our scrap by red metal, brass, cold rolled and stainless - not paying attention to the different grades of either.

Why is the grade so critical to your function?

Is there a price difference?

Doesn't the mill test the chemical composition and add as needed to develop a specific grade before before forming bars?

I'm curious...

I could be mistaken, but I was of the belief that Stainless could not be effectively "Recycled" (as in melted down), due to its low carbon content. You can only add stainless in small amounts to normal steel mixes.

Consequently stainless scrap prices are similar to mild steel, aren't they?

Re-selling scrap peices for re-use is a different matter...

Tony

You bet your Bottom dollar that stainless and all other metals can be remelted and recycled.

ALways have and always will.

Carbon is the least of the worries, as it will boil out any way.

The recovery of the 18% chrome, or 9 % nickel in stainless scrap is a huge incentive to recycle stainless.

Now, to the point about whether it would be a wise choice to include stainless scrap in a charge for a plain carbon or lower alloy steel, the answer is of course not. The limits on residual elements, (those not intentionally added) are low enough that any significant stainless scrap would over shoot the minimum. For example, we used to hold Chrome as a residual to .15 weight percent maximum in our special bar quality melts. adding just one ton of 18% chrome stainless to a hundred ton heat charge puts us out of spec... (.18 wt percent >.15 wt percent) And that is not counting the trace amounts of chrome in the balance of the 100 tons of charge...

By the way there is no commercial means to "filter out" the differing metals that make up an alloy, which again speaks to the need to maintain grade identification of remelt feed materials.

The ability to rationally remelt is EXACTLY why the original poster wanted to know how to sort, so that he could be paid a higher amount for his returned material, so that it could be remelted in a rational manner.

milo

First, I like to thank all for the replies to my question. I would work on them to see if I would be capable to tell the difference with the options listed.

To answer some questions posted.

Different grade of materials have different contens. During the melt down process, impurities had to be filtered out to obtain the required 'pure' composite required to produce into 'raw' material. The process cost the recycler labour, time and of course $$. Thus, the different grade of a same metal would have different scrap prices. For example, copper with carbon would have a lower value compar with copper without carbon. Furthermore, some metals could not be melt down as effectively as other material, i.e., lost of material during the melt down process, that would also affect the scrap price.

I only do collection of metals for recycling. I am not invlove in the process of melt down, thus would not know if stainless steel can or cannot be melt down effectively. The current price different for mild steel and stainless steel is about 300%, being stainless steel having a higher scrap value.

Hopes that I am able to answer to the queries and would welcome more options and ways to be able to tell the 2 grade of stainless steel apart.