Hello, made a spring swage for tenon work and would like direction on how to properly harden, as this will be used under a power hammer. Thank you

I don't own a power hammer so those that do can probably answer far better than I.i would assume you could use "as forged" or normalized 4140 under a PH no problem but lets see what others with more experience have to say.

First, ROUND THE EDGES!  Sharp corners on a clapper die like that are bad bad bad.  Your side to side relief looks good but in the front to back axis the edges are too sharp. Then tell us what you did to relieve the stress/HAZ (heat affected zone), looks like it was a cold  piece of 4140 you welded the spring to?  The weld will fail unless you use the correct wire/filler rod alloy and pre and post heat.  (In fact the weld will fail eventually no matter what but it'll last a LOT longer with good alloy wire and some welding pre heat)

All that being said normalized or "as forged" 4140 will hold up just fine for anything short of heavy industrial usage if you only work hot steel between the dies.  In normal use it's probably going to get hotter than tempering  temperatures anyway so I'd just normalize the whole thing and get to working.

Will do on the rounding of the edges. I was sure it was enough, they ramp down quite a bit from the original i.d. of 1/2". Will take a better pic tomorrow after some finesse work has been done. As for the welds,counter drilled hole 3/4" deep and pressed chamfered round stock in, then tig welded, no post heat. time will judge, will report back with results and any failure. Thank you !!

I believe the sharp edges on the outside is what was suggested you round off, not the rounded ones on the inside.

Correct, it needs to be rounded some in the direction of feed. As it is the sharp edges can create ridges, and possible cold shuts in the workpiece. 

As to the welds. I would do a little post heating to temper/anneal them some. The weld is enough to harden, and make them brittle.

Soft as can be I say. I would rather mar up something like that, than my dies.

ok.....cleaned up all edges, will give it a run this weekend.

Looks good, radius and fairing are your friends when it comes to neckers.  We dont go to too much effort in attaching handles to tools, (ie counter boring, tenoning, etc) as the handles will still normally always fail just at the end of the weld where it meets the handle.  Even preheating and post heating have very little bearing on the life of the attachment.  Just use the neckers normalised.  We have varied sets of neckers that are up to 10 years industrial use that are 4140 only normalised.  Still going strong.

Phil

i am new to tool making....please elaborate a detailed normalizing process. Thank you

There are pinned threads about that, at the top of the page....

nothin'??

Normalized is the unhardened state. If your pieces have not been hardened yet then they are in the normalized state already. Heat treatable steels usually come in a normalized state so they can be cut, machined. This allows the final product to be heat treated to their required specs. 

If a piece if steel has been hardened it can be normalized by heating to the critical temp but cooled down very slowly. Different alloys have different specs.

Most the alloys I see come as annealed for machining work. Normalizing is often done as stress relief after machining

My bad, I read normalized but was thinking annealed. Sorry for the confusion!

NP blame it on the weather....

cold and rainy in El Paso TX

ok.....so just run it as it is....thanks fellas !

Most 4140 will be in the normalized state...that is to say that it's not hardened. Some of it comes pre heat treated though, which we use pretty often at work. Usually only 28-32 HRC, so it's still relatively easy to machine.