Metal identification tool

[mklotz]

Being able to identify the material you're about to machine has many advantages. Sadly, we all have plenty of "who knows?" material in the stock rack.

One way to identify metals is the spark test. The unknown is applied to a grinding wheel and the color and form of the sparks are "analyzed" to make the identification. Other tests involve applying acids or chemicals to the material and noting the reaction or lack thereof to identify. The internet will provide plenty of spark illustrations and chemical approaches.

Unfortunately, all these tests are rather subtle and, with the multiplicity of metal formulations available today, easily subject to error.

It helps immensely to have samples of different metals available for both spark and chemical testing. Being able to perform the test on a known material and observe the outcome makes interpreting the test on the unknown much easier.

Whenever I encounter a material whose pedigree is known UNEQUIVOCALLY, I grab a sample, drill a hole in it and thread it onto one of my two sample chains...

Most of the samples have their identification engraved on them. Smaller samples have an identifying number with details for that number on an accompanying card.

If you belong to a model engineering, hobby machining or live steam railroading club, solicit your club-mates to provide samples to their fellows. That's how many of these samples were obtained. Stress the fact that the metal's type must be known beyond doubt.

Another advantage of having such a collection is that it provides an opportunity for accessing the machinability and job applicability of a particular material prior to committing to buying a lot of stock that turns out to be not ideal for the intended use.

[Frank S]

When I go to a scrap yard in search for materials I usually take 3 things with me my automatic center punch a good sharp small file and my pocket knife.
Identifying most structual steels and pipe is a non issue except for sheet and plate steels since there are many harder and tougher grades in this area such as ASTM 514 or "T"1, or AR 400 T! can be identified if you have a piece of known mild steel such as ASTM A36 handy and your automatic center punch the punch mark in the T1 will be significantly smaller than one in mild steel for AR 400 the punch mark will almost be non existent npw comes the knife test a good pocket knife like my 40 year old Ka-bar will make a gouge in mild steel , just a scratch in T1 and barely a mark in AR 400 . 3 good strikes with a file on the edge of mild steel using the corner of the file will make a good "V" a much smaller one on t1 And just dull the edge on the AR400
Another good indicator is if the piece has had previous processing T1 can be formed but the bend radius will be twice as large as a comparable piece of mild steel of the same thickness AR 400 which is a wear resistant plate is rarely ever formed to more than a 45° break and the bend radius will be huge This is not to say that all formed materials with a huge bend raduis will be the tougher or harder plate stock many fab shops use a bull nose punch to purposely form larger bend radius depending on their requirements
If the steel has been sheared have a look at the sheared edge a clean edge with little to no surface deformity either on the top or bottom side will indicate mild steel the tougher the steel the more the surface near the edge will be compressed very hard materials will hardly ever be sheared.
When buying round bar stock I often try to find hydraulic cylinder rods they are always made of tough steels but sometimes are induction hardened making them nearly impossible to use you can't cut them with a band saw and will dull even be best cutters in a lathe for this I use my file again if it will not make a scratch in the chromed surface I pass it by

[DIYer]

Thanks mklotz! We've added your Metal Identification Method to our Storage and Organization category,
as well as to your builder page: mklotz's Homemade Tools. Your receipt:

Metal Identification Method by mklotz

tags: organizer