A2 airhardening

Anybody knows the correct temperature to temper it to ~ RC 40-45 after
hardening?
This is 3/4" rod.
cheers
T.Alan
Reply to
T.Alan Kraus
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You're off the charts, but 1100F would give you about Rc50. A2 is not generally recommeded for use below Rc55-57 - if you need extra toughness there are better choices.
Ned Simmons
Reply to
Ned Simmons
Thanks, would oil hardening O1 be better?
cheers T.Alan
Reply to
T.Alan Kraus
Probably not. What combination of properties are you looking for? Rockwell hardness is often not an end in itself, rather it's a convenient indicator of the overall properties of a chunk of specific material. For example, toughness and wear resistance will vary widely between different materials of equal hardness.
Since you're asking about drawing back to Rc40-45, I assume you're looking for something relatively strong and tough. In that case, 4140, or a similar alloy steel, is a possibility. A socket head cap screw is an example of alloy steel in this hardness range.
Ned Simmons
Reply to
Ned Simmons
I am searching for some easy to get round stock that is dimensionally correct without having to turn it, and is wear resistant enough to accept a bearing while enduring heavy side loads. Something like an axle. I'm aware of prehardened 4140 to RC 35-40 that is still machinable, but I haven't been very happy with the finish I was able to turn it to.
cheers T.Alan
Reply to
T.Alan Kraus
If all you need is a straight shaft, Thomson shaft should do the trick. It has a hard case and a tough core. The usual stuff is .0005-.0010 under nominal, but there are other diameter limits (Thomson call them "classes") available. McMaster carries the standard class in inch and metric sizes starting on p.988. The hard case is machinable with carbide, or it's possible to spot anneal with a torch, though it's best to do this only on the ends of a piece if you need to maintain straightness.
Dowel pins are another possibility if you just need a simple pin.
If you need a more complicated shaft, "stressproof" will approach the 4140 prehard in strength/toughness, but is much nicer to machine. But it will not be accurate enough as-is to use in a bearing. Look on the bottom of McMaster page 3441.
Ned Simmons
Reply to
Ned Simmons
Thanks Ned, good info.
cheers T.Alan
Reply to
T.Alan Kraus
Just as a comment, I've seen some pretty nice stuff turned (and milled) from 4140 Rc 35-40. Perhaps a closer look at the tooling/setup/methodology you are using?? At any rate, good luck!
Ace
Reply to
Ace

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