Thread: Steel analysis labs

Hi Bob,
Not sure on places that do it commercially, but failing all else surely one of the UNI's up there would have a mass spec or something that you could get them to use. I have found in the past that they are only too happy to help, especially if they can work it into their curriculum. I guess it also helps knowing someone who works there.....

Cheers,
Ew

You need one of these...... Positive Material Identification-Handheld Niton XRF .... though at around $7k it seems they dont come cheap
Can I borrow it?

Stuart

Surely you would have a metallurgical microscope by now Stuart.
All you need then is a diamond lapping machine and some acid and we are ready to go.

Grab these things Bob and analyse them yourself. It's easy to do.

Phil

Some of the more sophisticated casting places have an electric arc device to analyse the results of the pour.

Michael

Michael is correct. I saw one demonstrated at Doug Slack's foundry at Emerald in the early nineties.They carved off a small sample the size of a small thumbnail and applied an arc to it in a machine that looked like a microwave oven. Moments later a roll like a shopping check out docket was spat out providing the chemical make up of the steel.

It provided percentages of the constituent like the carbon content and the alloy metals.From that it pretty easy to work out what you have. The foundry was able to analyze a sample and reproduce it exactly.
Grahame

Originally Posted by bob ward

I have a heap of good mystery metal, some sort of high tensile I believe (used to be the vertical tie rods in a timber truss bridge), out of curiosity I would like to find out what it is.

Minor gloat, paid $100 at auction for 20 metres of 2 5/16" round - 23c per kg.

Hi Bob

If the tie rods came out of an old timber truss bridge it's very very unlikely that the steel is anything more exotic than your general run of the mill mild steel.
Depending on the age of the bridge it might be BHP Newcastle's best or from Aust Iron & Steel at Port Kembla.

From what I recall from reading a set of generic bridge plans 35+ years ago, the timber truss tie rods were specified as mild steel -- principally so the on-site blacksmith could work them and cut threads, etc

That makes sense Ian, maybe the timber bridge story is wrong. This steel is definitely a better grade than 1018 etc. Its tough but turns well and I get amazing finishes on it and it takes forever to go rusty, it behaves more like one of the 4xxx steels, not that I have too much to do with them.

One of the reasons I want to find out the alloy is that it may help in my quest for chip control, I've been unable to find the sweet spot at which it chips, and continuous swarf is a PITA.

Spark testing use to be a basic workshop practice, not done much these days! Works best when you have known samples to compare from. But it will tell you whether you have wrought iron, mild steel or some high carbon/alloy mixture !? Graeme

Originally Posted by anglesmith

Spark testing use to be a basic workshop practice, not done much these days! Works best when you have known samples to compare from. . . . .

There is a fantastic analytical instrument called an LAICPMS (Laser ablation inductively couple plasma mass spectrometer) that will simultaneously measure almost every element on the period table in a solid sample. The instrument continuously fires a laser onto the surface of the sample (typically about the size of a 10c piece) and vaporises a tiny pit off sample some 25 microns wide and the same amount deep and sweeps away the vapour using ultra pure argon gas into a plasma chamber which ionises everything and analyses what is in the vapour. Unfortunately a quality instrument only costs about 1.5 really big ones so analytical costs are high to recover the cost and running of the instrument. The analysis of the sample is quick ~20 minutes but like all analytical instruments it is essential to have reference samples or standards. So it's no good finding a lab with these instruments unless they have access to the standards. I know a number of labs that have these e.g. UQ, Macquarie, UWA, but I do not know any that have the necessary metallurgical standards.

A cheaper analysis (few $) can be performed using a conventional ICPMS (same as above with no laser) but these machines can only analyse solutions or gasses so solid samples have to be dissolved in acid. But once again without standards the results are unreliable.

Coincidentally, I just so happen to be in the middle of reviewing an 81 page scientific paper on standards for these types of instruments.

Finally got my steel analysis done, and as a freebie too which is always nice. Turns out a bloke I know knows the chemist at a major foundry which of course has all the good analysis gear.

C .45%
Mn .86
Si .26
Cr .90
Mo .18

Looks likes what I have is heaps of 4140 or 4340 or thereabouts, anyone who really knows their steel alloys please chime in.

Now to do some research on how to turn it without getting a long nasty ribbon of swarf.

Originally Posted by bob ward

Now to do some research on how to turn it without getting a long nasty ribbon of swarf.

Negative rake tools and high feed (.25mm/rev +) have always worked for me, and a decent DOC. As soon as the DOC drops the nasty ribbons appear.

Ew

Thanks Ew. When ever I tackle this material I use CNMG 432 inserts and I reckon I have tried just about every combination of speed, DOC and feed the lathe has - Hafpos 2hp 14 x 40 - and always get the nasty blue ribbon, no chips.

But industry turns tons of 4140/4340 so there must be an answer. What would be your starting point for steel 55 dia? Available speeds in high are 2000, 1300, 710, 450.

I'd be starting at 700rpm and going up. If you have information on the insert it should tell you a surface cutting speed. HSS is around 30m/min and would be run at 163rpm. If the insert speed is say 150m/min then you need 5x the HSS rpm. You do need the DOC and feeds high for chip breakers to work though. Lots of smaller lathes just can't do it as they are not rigid enough or have enough power. Yours may be solid enough. (mine is 4HP and sometimes the chipbreakers work, sometimes they don't)

Michael

Looks like it could be 4140 which is quite common in Australia. It can't be 4340 as there is no nickel content.

Lex.