Help at identifying metal

[andrewgr]

I'm a novice at machining. I've probably spent a total of maybe 3 hours actively cutting on my mil-- much longer than that setting up, of course. (It's a PM 728-VT, if it makes a difference.)

My cousin is really into building buggies and trikes and such, and he has a lathe and some other equipment. But he doesn't yet have a mill (I think he's saving up to get a CNC mill, rather than spending money on a manual.) He asked me to do some simple milling for him, and I agreed. So he sent me two pieces of "mystery steel". He spot welded them together, because each of them needs three holes drilled and bored to size, and they're supposed to match, and he thought it would be convenient to just drill and bore the holes at once, to make sure they lined up. I have misgivings about that, so if you have an opinion, feel free to chime in.

The steel he sent me doesn't seem similar to any of the steel I currently have, which consists entirely of 12L14 and 1018.

I've read cautions about not cutting mystery steel if you're a beginner, but all I need to do is drill and bore three holes. I don't mind breaking a drill or a mill tool, and I'm careful with wearing a face guard / helmet, so unless someone is absolutely adamant about it being too dangerous, I'd like to give it a go. I figure it will be a learning experience, whether I'm successful or not.

But I have no idea which tools or what speeds and feeds to use. I'm prepared to experiment, but I'd feel much more comfortable if I had a reasonable guess at what my starting values should be.

With that in mind: does anyone feel like they can hazard a guess as to what material is pictured? And/or, does anyone have a test I can do (without having specialized equipment like hardening gauges) that would help narrow it down?

My primary concern is determining if it's hardened or if it's stainless. If either of those two things are true, I might re-think the attempt, or at the very least I'll do more reading about it first. Otherwise, I don't think I'll get myself into too much trouble with a non-hardened alloy.

Any related suggestions or advice is welcome, too.

 

[extropic]

No way to be sure what the material is from a photo. Stroke an edge with a file to be certain that it's soft enough to cut.

If the file cuts it, assume it's mild steel and machine accordingly. Feed and speed charts are all over the web.

 

[markba633csi]

Test it with a magnet, if it seems to be stainless then it will be hard to cut but not impossible. If it sticks then it's steel but it might be a higher carbon steel like 1045.
Again, harder to cut than garden variety but not impossible. You might want to use a cobalt drill bit. Do the file test like extropic mentioned.
-Mark

 

[Jonas302]

Looks like it had mill scale which lead me to hot roll mild steel
its not stainless
it took a centerpunch mark so not superhard
you can file an edge and see how it cuts compared to something you know

Or stick a drill and make chips

 

[Canus]

BTW some stainless steel is magnetic. Agree with checking hardness with a file. Also spark test will give some idea of Carbon content.

 

[hman]

400 series stainless steels are mildly magnetic. It's pretty easy to feel the difference in attraction if you have a known piece of steel or cast iron nearby to compare.