Identification of tool steel

$75-$100 each lab test. Been there, done that, although I had a ton and it was worth it. After I made some parts on an assumption that bit my ass, I resigned myself to do the right thing.

First you can compare the sparks it gives from a grinding wheel to a known piece of steel and see if you can match it up. This will put you in the ballpark. You can also heat up a piece untill it loses its magnetic attraction and then air cool it. If it gets hard it is an air quench steel possibly A2. Do the same thing again with an oil quench and see how hard the surface gets. O1 steel is a lot cheaper than air quench steel but the air quench doesnt move as much when its quenched and will give you better thru hardness.

There are so many types of tool steel you reall have to have it tested if you want to know the exact type it is.

John

Highly upsetting. Thanks Tom.

Thanks John. I will see what I can do. What steel are drill bits and taps made of?

Anyway, I was kind of hoping that there is a kit with some chemicals that I could brush on, if it turns pink it is A2, if it is purple it is 4140, etc. Seems like there is no such animal.

Well, you can do a spark test on the grinding wheel and compare it to a known alloy. Reading sparks is an artform in itself. Got any old-timers around?

I decided to just call the owner (with whom we developed good rapport).

He told me that it was 4140.

Ig:

SAE 4140 is not classified as a cutting tool steel. It is a high quality machinery steel that can be heat treated to through-strengths of over 200,000 psi in sections 2" dia. or less.

However, some people I worked with made paper cutting label and envelope dies from this stuff, hardened right-out to Rc 52. The customers seemed to like it.

It is really more suitable for hard-working components such as shafts, work and tool holders, pinion gears, arbours and mandrels, draw bars, in short anything that needs to be strong and tough.

Cutting tools such as drills, raps, reamers, etc. are nowadays made of high speed steels of varying types and qualities.

Try to lay your hands on a little booklet from Crucible Steel Service Centres: Tool Steel and Specialty Alloy Selector. Most informative.

Wolfgang

For stainless identification acids are used, but I don't remember the exact procedure. You brush it on and watch for any discoloration.

Its not that hard to distinguish carbon steel from alloy steel. The spark test will put you in the ballpark with carbon steel, and a quench and hardness test will give you an idea of the carbon content by the hardness. 1018 will not get at all hard. 1045 will get to about 54 rc. ( a file will scratch it but not too deep). 1095 will get file hard.

John

The spark test will tell you more of what it isn't than the exact alloy it is. The sparks themselves are the carbon in the metal burning up.

John

Thanks Wolfgang. I read some descriptions of 4140 by now, seems that you are right.

Looks like it's available online now