Heat Treating hammer dies

[pike3e]

I am heat treating some h13 hammer dies for a local blacksmith as part of a trade. The dies are about 20lbs each and are for a 120 ln bulll hammer. My question is do I need to foil wrap these in order to prevent decarb or will they be fine without it?

Thanks

John

[macbruce]

I'm sure someone here will get more technical but my experience with H13 is to let it soak in the gas forge at a non nuclear temp and simply let it cool.....works for me.... B)

[ciladog]

John,

You should wrap the dies in foil for two reasons; to prevent decarburization and more importantly to quench slowly in still air. Put a piece of paper in the foil package with the die to consume the oxygen.

When you’re making something for your own use you can do just about anything. If the tool or die fails only you are to blame and only you may get hurt. Making tools and dies for someone else is another matter and should be done correctly.

I have made a fair number of large dies from H13. The dies are only as good as the heat treatment.

A 20 lb block of steel takes a fair amount of time to come up to even temperature throughout. H13 needs to be preheated to 1400-1500 F and then brought up to 1800-1850 F and held there. The soak time is 30 minutes for each 1 inch of thickness of the thinnest cross section. So a 3 inch high die would soak for 1 ½ hours.

Then let the dies (in the foil) cool until you can handle them with your hand at about 150-125 F and begin the tempering immediately. Yes, H13 dies should be tempered. Tempering H13 takes a long time, 2 hours per inch and they should be tempered twice. The second cycle should be about 50 F lower than the first. Tempering at 1000 F will give you a Rockwell C of about 48/50.

Now I realize that the above is an ideal situation and unless you have a heat treat oven or as I use, an old pottery kiln with a programmable controller attached to it, you won’t be able to be that precise. But the benefit of using H13 for dies is in its properties after heat treatment.


Also know that H13 should not be welded cold because it will create stress cracks at the welds. H13 should be heated to 900-1000 F before welding. I usually do any welding right after they come out of the tempering.

[pike3e]

thanks for the info. I do have a kiln, I am just low on foil and was wondering if it was necessary to order more. Sounds like I will be making an order.