Identifying stainless steel grades

[1.8T]

Is there an easy way of finding out what grade of stainless steel a something is, say i had a box of unmarked stainless steel bends and some where meant to be 304 and others 316L how would i tell them apart? thanks

 

[TechnicAl]

If they are not marked its going to be difficult. There are machines that can be used to Identify. A local scrappy may have one.

 

[hotrodder]

Ever wonder where the phrase 'the acid test' originated? (probably somewhere else). FWIW You can buy kits although they're not even close to cheap so sit down before clicking the link... http://www.elmerwallace.co.uk/Stainless-Steel-Identification-and-Test-kits/C10-1-0.htm

I'd go with Al's suggestion first and try waving a drink at the local scrappy if they've got one of those posh machines

 

[Shox Dr]

The only thing a scrapyard will have is a magnet.

Off topic; Unless you have a large amount of a given grade of SS that's worth more on it's own a scrapyard couldn't care less. And then you wouldn't be taking it to the local yard, more likely a specialist reclaimer

 

[KemppiFrog]

The acid test might refer to Gold. Wipe the metal on a 'touch stone' then a drop of nitric acid on the smear. Colour gives the answer.

HR, interesting site. Expect one gets a number of tests out of a kit, so perhaps not so pricey.
KF

 

[1.8T]

Interesting thanks all, more concerned tbh with buying some custom made parts online, i want to know that they have actually used the grade of stainless i specified (and paid £££ extra for) rather than 304, would these tests damage the stainless though? this stuff http://www.elmerwallace.co.uk/23.100-Molybdenum-test-for-AISI-304-vs-316/97.htm although expensive works out at less than £1 per test before vat and i really have got a box load of unmarked bends to sort though and id, would need to check that solution will work with 316L

 

[Paul.]

It does work, I first came across it some years ago, we built a snack food processing line to go abroad and before the customer allowed us to send it they tested all the stainless to make sure it was 316, it does leave a stain but is easily removed by using garryson blocks or scotchbrite on grained material, or a rub with a polishing mop on bright finished, mostly just used it where it dosen't show though,

 

[hotrodder]

The acid test might refer to Gold. Wipe the metal on a 'touch stone' then a drop of nitric acid on the smear. Colour gives the answer.

HR, interesting site. Expect one gets a number of tests out of a kit, so perhaps not so pricey.
KF

Yeah, as said cheap on a per test basis if you've got shed loads to do/it's an ongoing thing. I was picturing something along the lines of curiousity about a box with say 20 odd bends in it

 

[KemppiFrog]

Yeah, as said cheap on a per test basis if you've got shed loads to do/it's an ongoing thing. I was picturing something along the lines of curiousity about a box with say 20 odd bends in it

Yes, then it would be handy to know some one with the kit
KF

Of topic: We did NDT on aircraft parts with dye test. But only to confirm/deny what we thought we could see. If it was serious, we got a specialist in with magnetic flux kit. Way too pricey for a small outfit like ours.

 

[Terrapin]

We use a metascope at work - readily identifies different alloys in our materials receiving section. I bet they are expensive though. Unless you can find a local firm that will allow you the use or indeed check your stock for you.

 

[TechnicAl]

Terrapin..........could you check them for him?

There is a chemical method somewhere in ASTM STP (standard test procedure) but I dont know the number.

I hesitated to mention it as it involves strong acids with the dangers that involves. If you can find it its probably cheaper than the Elmer Wallace stuff.

I didnt know about the Elmer Wallace stuff but it appears a lot safer than strong acids

 

[Wedg1e]

We use a metascope at work - readily identifies different alloys in our materials receiving section. I bet they are expensive though.

The new PMI units are expensive. They usually use an x-ray source that is reflected/refracted differently according to the metal's poperties.

The old Metascop (no 'e') used a tungsten electrode that was vibrated rapidly so as to create an arc that would vapourise a small patch of the test metal. This then creates a spectrum of light which is passed through a prism to spread it out; different metals produce prominent 'bright spots' so you observe the spectrum through an eyepiece and consult tables to identify the metal.
Took a lot of experience to be quick with and if you lost the tables you were slightly knackered
However they do pop up at auctions from time to time and are worth snapping up if you see them; they rarely go so wrong that they can't be fixed (I think I've scrapped two in 18 years) and are operator-calibratable (if that's a word). If you pay less than a grand it's a bargain. They are internally wirable for 110 or 220V so don't worry about the colour of the plug.

 

[1.8T]

Trouble with those test kits from elmerwallace is the shelf life, the expiry on the ones they have in is march next year, now i dont know how critical expiry dates are on those kits but i wouldnt want to spend £120 odd to do dozen tests now only to find the next time i want to use the stuff its gone off and isnt giving accurate results, would be good to try and find someone local with a handheld machine that can test them for me for some beer tokens