Heat treating larger pieces in the forge

[jmccarth]

Hi guys

I've been lurking in the backround for a while and have really enjoyed the forum. I have recently come across a small problem I was hoping some one here could help me with. I am building a Kinyon style hammer and have machined a dove tailed sow block and some variouse dies to fit it. I wasn't thinking when I picked the steel and went with three different types of tol steel because thats what I had on hand. I forgot that hardening is by material type. So thats $100 per type of steel to treat. Taking away all the savings from using the steel I had on hand.

My question is has anyone here had success heat treatin heavy ish pieces in a forge. I'm considering doing so myself. I just don't want to gaff the job and catch a piece of supersonic O-1 in the kisser. The materials I used are 420SS 4140 and O-1 All are taken from 2 x 2 and larger stock and in the 5-7lb realm. I'll atach some picks. I've been thinking about just leaving them unhardened, any thoughts, I relly do want them to stand up for a good long time.

[evfreek]

Hi jmccarth. When you say $100 per steel type, do you mean $100 in professional steel heat treating fees, or $100 in steel costs. I am suspicious that it is the former and that you acquired these pieces of steel as drops for a low price. In that case, either find a different heat treater who is more minimum order friendly, or bite the bullet and focus on only one type of steel. For example, 4140. If the $100 is for steel, you should have bought drops over the Internet, since $100 is a fair price for new tool steel in this quantity. And you should expect to pay more for the tool steel than for mild steel. Maybe 5-10X, not counting heat treating charges. If you want to get by without heat treating, you can start with 4140 PH (pre-hard, which although softer than full hard, is harder than annealed or mild).

I have a buddy who is a paramedic. He once responded to an emergency call at a heat treating company. The guy was unconscious in a pool of his own blood. My buddy said that the exit wound looked like he had been shot with a .38 special. Don't quench the 4140 or O-1 in water unless you know what you are doing (it can be done, and there are facilities who do this routinely).

[jmccarth]

The steel is what I had laying around. Not free but already paid for. The $100 is for each type of steel at the heat treat facility. Its the best price I could find. Induction would be $120 per set up 3 set ups. I'll bite the bullet on the $300 before I go and re-make these. I have a manual machine and it took a while to cut that dovetail.

[Dodge]

Jmccarth, GREAT looking dies! Beautiful machine work. Since you will (should) be hitting softer steel from it being heated than the dies, you might get away without heat treating. Besides, I don't believe the receiver, (bottom part), (die holder), needs to be as hard as the die. Tool holders usually are not as hard as the tool. That would save at least one c-note:)

[HWooldridge]

I can tell you from personal experience that I would recommend getting them professionally heat treated. I had a set of H13 dies made for a 100 lb hammer but they were too soft and were heavily damaged in just a few sessions. I had the faces recut and the dies sent out for heat treat. They came back around 50 Rc and have been in continuous service for about 15 years.

[jmccarth]

Dodge thanks, I'm really happy with how they came out. I'm almost finnished with my hammer, 75lb head including the dies. I am leaning twards just hardening the dies. The Sow block is made of O-1. It should hold up with the mass of the anvil and the tight fit of the dies I can't picture much impact force. The Anvil is 300+ lbs of 6" rnd CRS with a 2" base and 2" butress suports and a 7" rnd crs cap. With all that mass the die block should tranfer the force. Does anyone know if the die holder of production hammers are hardend?

[ThomasPowers]

Try to find a heat treater that will piggyback your pieces on a run they are already doing and so no "set-up" charge just the cost per pound for the HT

[nonjic]

jmc - Im a newb here but have a bit of experience on making hammer bits, if you really want to increase the life of the dies I would dress some proper rads into the corners of the dovetails (especially the sow block) - you've got some major stress raisers there at the most common failure point.

Youve gone pretty sharp in the corners so you may have to undercut them a bit, but they will stil be a whole lot stronger than they are now.

If you use the edge of a blue flap disc in a 4 1/2" grinder you can get smooooooth rads real quick.

[Rich Hale]

Your comment about getting smacked in the face can be easily solved, just weld on a handle to the ends of them and cut the handles off later. You did not mention what kind or size of forge you have or have access to. When I did my dies of 4150 I heated the forge and put the die in and turned the forge off, let the die soak for a while then I fired up and let the forge heat and turned it off for a while I wanted to let the heat soak in to the interior of the piece and not just surface harden. after about three sessions I fired the forge and let it come up to a non magnetic red. I turned the forge off and let it darken a bit and repeated I did this three times also. I oil quenched and that takes a big bucket of oil. A welded on handle is worth gold then. I tempered in the oven for along time I think it was aboiut 8 hours before a file test let me know it was softened enough not to be brittle and chip. I don't have specs on the SS you used but you should research the data for that particular ss. the SS I use requires very specific heat treat temps and times. As was mentioned above if you can put your stuff in a larger load of steel to be heat treated you may save some money. REsearch anyone in your area that is useing the steels you used and see if they send thm out and if you can send yours with. I would start at the heat treat place and see who sends them the same SS as you have and go from there.

[mark stephen]

Heat treating 0-1 and 4140 are simple and not dangerous.Both are deep hardening steels because of the alloying in both.Bring the 0-1 to 1500f and soak for a couple of mins and quench in 100f-150f oil.Never use water.Tempering should be done right after the quench and the temp. you temper at will depend on the rc hardness you want the final piece.4140 is heated to 1500-1550,soaked,then it is also quenched in oil(100f-150f)again,dont use water.Look on the web for a tempering time/ temp. chart to get an idea of how to achive the final hardness you want in the piece. Salts are better than oils because you can cut down on the shock of quenching and distortion.

[jmccarth]

I think I'm going to send out the 420ss and try the rest on my own in my forge. My home forge is a large coal forge with a vulcan fire pot It shouldn't be a problem bringing the steel up to temp. Does anyone have experience juging temp to a close tolerance in a coal forge. My plan is to use heat crayons for heat and temper. The sow block is O1 and the Flat dies I built are 4140 any sugestions on temper heat?

[patrick]

The die holders of most hammers are not heat treated, in fact, on most mechanical hammers they are cast iron. There is no need to heat treat the die holder, regardless of steel type. The dies themselves should be heat treated, but sharp corners in the dovetails will act as serious stress risers and can result in cracks either during quenching or in service. If such a sharp corner is absoultly necessary, it should be machined in after heat treat is complete. I would recommend that you look into having the heat treat work done at American Steel Treating in Perrysburg OH. They used to do knives for me and for any job under 20 lbs the price was $20. That was about 10-12 years ago, but I still doubt they would chage $100 to do your dies since they will batch them with other work to make a furnace load. There is no advantage to using induction heating on your dies since they are not of uniform cross section (round or square). Custom coils would have to made for the dies, and there is just no reason to do that.

Patrick