Identifying steel

[DavidR8]

I have a few pieces of steel that are part of a trove of machinist stuff (metrology gear and tooling)
One length is perfect dimensions to make T-nuts for my mill. Problem is that it's so hard I cannot seem to mark it or even make a dent with a centre punch.
I'd like to figure out what it is so I can figure how it can be used.

 

[ACHiPo]

I have a few pieces of steel that are part of a trove of machinist stuff (metrology gear and tooling)
One length is perfect dimensions to make T-nuts for my mill. Problem is that it's so hard I cannot seem to mark it or even make a dent with a centre punch.
I'd like to figure out what it is so I can figure how it can be used.

Sure sounds like tool steel. You can grind it and look at the sparks, but unless you have known samples to compare, it won't be definitive.

 

[MrWhoopee]

If it's so hard you can't put a mark on it, it's a parallel. You can grind it, but you won't be milling it, much less drilling and tapping.
You MIGHT be able to anneal it, but the potential cost in destroyed tooling will probably exceed the value of the tee nuts. Find another piece.
I found a couple like that in my trove. They are now parallels.

 

[pontiac428]

X-ray fluorescence is probably the best tool for determining the composition of an alloy; for the rest of us, there are spark tests, which can be very useful with a little bit of practice. Usually a good idea to start with a magnet to include/eliminate austinetic species from the testing hierarchy. Spark test info can be found in all of the good shop reference books.

 

[Bob Korves]

Using a hard t-nut will be rough on your table t-slots. Make the t-nuts out of mild steel with all the edges and corners carefully rounded to a significant radius and smoothed. T-slots and t-nuts are part of the de facto precision of the mill, in my opinion.

 

[DavidR8]

Thanks all! Mild steel shopping I will go

 

[ACHiPo]

Using a hard t-nut will be rough on your table t-slots. Make the t-nuts out of mild steel with all the edges and corners carefully rounded to a significant radius and smoothed. T-slots and t-nuts are part of the de facto precision of the mill, in my opinion.

And Bob once agains separates the wheat from the chaff!

 

[Ulma Doctor]

a spark test would be in order to determine the flavor of steel

you can make t-nuts from steel, bronze, or aluminum or anything else you have access to
just realize that other materials may yield before steel would.

 

[WCraig]

"THATLAZYMACHINIST" (Marc) has a video on identifying types of steel:

Craig

 

[ericc]

If it is a parallel, you can indicate it on a surface plate and it will be parallel. This is too valuable to use to make t-nuts. It will probably be some standard dimension. If it is HSS, it may not be useful as a parallel (poor dimensional control), but can be used as a cutting tool. A spark test will tell right away.