A2 steel

[winklmj]

The local scrappy has a bunch of steel marked A2. Some really nice looking stuff and he rarely has any steel I would find useful. This is 1x2x8" blocks, some 3x4x8", and some bigger pieces. Also some 1 to 1-1/2" rod about 2 feet long.

Is this something easily machined on my little 7x14 lathe and X2 mini-mill? HSS or Carbide? If so, I'm gonna go grab up as much as I can carry--$0.25 a pound.

 

[shred]

"A2" is an air-hardening tool steel (assuming it's not just something somebody marked for bin "A2" or something).

May not machine all that well, but worth snagging anyway, if only for trading matter.

 

[doc1955]

I have worked with a-2 quite a bit. It is a little tougher to machine but does machine nice and the nice thing about a-2 if you are heat treating is warping in minimal. You should wrap in stainless wrap with a bit of paper sealed in with it to burn up the air within the wrap. Once heated to proper temp off the top of my head I believe it was 1750degrees F. needs to soak at the temp for 1 hour per widest cross section. It is a very good wear resistant tool steel. And unheat treated it is very usable I actually like working with it just for its stability. At .25 a lb and I had the chance I would be grabbing all I could.

 

[MailleMas]

The shop I work in uses A2 quite a bit as well, and Doc1955 has the right of it. We pre-heat to 1200 for the 1hr/in of largest x-section and then 1750F is indeed what we use. temper down into the mid-to-high 50's RC with a double temper @ 900C. I have found it to be very stable and not overly tricky to machine (though it is slow going). When using HSS cutting tools, I usually end up with a surface speed of 35-50sfm.

 

[winklmj]

I grabbed up a few chunks of it just because. They said that what's left is off to Pakistan tomorrow to be melted into who knows what. It turns out some is A2, some is D2, and some is CPM M4. I turned down a piece of the D2 just to see if I could do anything with it and it is slow going. A 5 thou cut with HSS ended up with a consistent 6' long curly chip. But my formerly sharp bit is now blunt on the end. I really need to figure out how to grind a more durable bit or just use carbide. A really nice finish though. I think most of this will get traded off to someone who can really make better use of it than I.

 

[Lakc]

When playing with tool or alloy steels, carbide seems to be the only way to go. Even the cheap soldered on disposables do a much better job then hss. Like you said, its one cut then back to the grinder otherwise.

 

[jonesie]

i use a2 alot at work and is good to work with as stated before it is fairly stable after heat treat. the d2 is tough and we use it alot for die wk. after heat treating you need the right wheel on the grinder or it will break down before you get across the piece, with the right wheel it does not grind to bad. the m4 is tough to work with it hea ttreats at a temp. over 2000and after that is is like grinding glass. the a2 is a good find and trade the rest, unless you want to make good planer replacement blades or wood chipper blade then keep the d2. the m4 is like what you hss tool bits are made of but they are usually m2. jonesie

 

[winklmj]

Thanks for the info. I have no plans or facilities to heat treat any of this. I just wanted some steel in small workable sizes for my mini-mill and mini-lathe. The scrappy doesn't typically have any for my needs (although aluminum is usually easy to find there).

In the past, my basic scrap-yard test has been--if I can file it, I should be able to machine it. These are a bit tougher than that although my little 4x6 bandsaw was able to cut through the D2 and a piece of M4 I fed to it. I'll hang onto the A2. I'm sure I can find someone who will want the other pieces.

 

[Admiral_dk]

Beware if you're in Europe and have a stainless bolt or nut - it will be marked either A2 or A4. A2 being stainless steel that's not acid resistant and A4 being stainless steel there's acid resistant (meaning hard to corrode, for instance in a salty environment).