Hi Giusseppe,
A have a couple of recomendations: A2 (Air Hardens)
D2-D7.
Very easy to find, I like A2 Tool Steel for it's tough properties, but most of all for the hardening process.
Heat then Air Cool!
There is no oil quenching.
"D"series is very common to the "S" series for Dies But has a little better resistance to the pounding a power hammer will deliver.
The steels you have mentioned will also work Quite well.
There are so many exotic Steels to Choose from. The question I would ask myself is how will Heat treat them.
Most of the Dies I have made for the Tool and Die Industry use the Most of the Steels mentioned.
Hope this helps.

Chuck

G-pepsi,

There's no real reason to use H13 for power hammer dies. H13 is best for uses such as hot cutters, etc where you have a thin section that is exposed to heat under use.

For power hammer dies, I like either A2 or D2, as both of them have good resistance to abrasion. You're unlikely to dent your dies that much, providing you aren't trying to work either cold steel or super hard stuff, and the greatest wear factor I see on my dies is from scale chewing up the surface. Properly hardened D2 is the best I hae found for resisting that wear. I haven't tried A2 for dies, only because I don't have any on hand in big enough sections to try.

For dies that you are just trying out a new configuration, I'd suggest using plain old A36 structural steel or 4140 and giving it a case harden with Kasenit #3 case hardening compound. That will take care of the surface wear from scale abrasion and allow you to try out new designs without having to go through any complicated heat treatments.

One thing to keep in mind on all steels for power hammer dies is that hardeening is, in many cases, a function of the sectional thickness. Thus, a deep-hardening alloy such as 4340 might be a good bet, particularly if you case harden the surface for abrasion resistance. Just a thought.

I guess it depends on the tool-
But I use a heck of a lot of Grant Sarvers Off Center Forge tooling, and it is plain old 4140.
And it lasts and lasts and lasts.
I run it almost exclusively on stainless, and have found that after 3 or 4 years of heavy use, the 4140 does lose some of its fine detail- like woodgrain patterns that are less than 1/16" in depth.
But for a good compromise between availability, cost, ease of use, and longevity, I think its perfectly adequate for swage dies and loose tooling.

Now if you are actually making dies for the hammer, thats different- I would use one of the steels Rich recommends for that.

thanks for all the info ... now to find the stuff somewhere ....

I have a lot of old hammers, particularly sledges ....what steel are they usually made of in North America ? They seem to work well as tools under the power hammer but I am not sure how to heat treat them as I am unsure of their alloy.