Javan C.R. Dempsey Posted September 28, 2011 Share Posted September 28, 2011 Might should have posted this in the HT section, but I didn't. Trinculo hooked me up with some nice unhardened 4140 dies for my Bull, and I'm looking for some advice on quenching. I've got a vertical blown gas forge that I can take the lid off of, and fit just the working portion of the dies into the forge, so getting them up to temp shouldn't be that hard. I'm going to heat them in sessions to try and even out the heat as much as possible, but I'm uncertain about quenching these. I've got 5 gal of really fast quench oil, Park HB #50, and I've also got plenty of canola. Will 5 gal of either of these be sufficient? The weight calculator tells me the actual weight of the die block itself should only be 3.4lbs, so that's below the 1g per lb rule I've heard tossed around, but the weight with the base plate is ~11.5lbs. The Parks 50 should be the closest approximation to water quenching for 4140, but it's expensive oil and I dont' want to overheat it, it's gentler than water so should harden well, but maybe I need to go with a higher volume of canola? I've only got 5gal of it atm, and not sure I've got a tank big enough for anything larger. Could I put my quench tank into a big tub of water? It's thin walled SS, but maybe not conductive enough to do any good? Thanks! Quote Link to comment Share on other sites More sharing options...
Stormcrow Posted September 29, 2011 Share Posted September 29, 2011 I have hardened dies for Gunnhilda from 3" square 4140 5" long in five gallons of the slow quench oil from Grainger. They hardened up just fine. Just put the die in the oil and leave it for a good while before you pull it out. You don't want to cool 4140 too quickly. I had some 2" x 3" 4140 that I made combination dies out of. I quenched in oil, left them for a few minutes, pulled out, and cooled one the rest of the way in water. It ended up cracking in the heat treatment. Expensive mistake! Quote Link to comment Share on other sites More sharing options...
Francis Trez Cole Posted September 29, 2011 Share Posted September 29, 2011 4140 is an oil quenched metal. I use canola oil for my hammers just heat them up and submerge them leave them. I also have a quench of used motor oil and diesel fuel That I use for punches and chisels.Heat Treatment This alloy is hardened by heating to 1550 F and quenching in oil. It is best to normalize the alloy by heating at 1675 F for a long enough time to permit thorough heating, followed by air cooling, prior to the hardening treatment. Forging 4140 may be forged at 2200 F down to 1700 F. Hot Working Hot working, if required, may be done in the range of 1900 F to 1500 F. Cold Working The alloy readily cold works in the annealed condition by conventional methods. Annealing Annealing is done at 1600 F followed by slow furnace cooling. Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted September 29, 2011 Share Posted September 29, 2011 Just a small note; 1550º; is not hot enough for blacksmith heat treating. A heat treater usually uses a soak of 1 hour per inch of cross section. Alloys are slower to transform than carbon steels and a little extra temp can substitute for a long soak. In this case 1600º seems to work well. Quote Link to comment Share on other sites More sharing options...
Javan C.R. Dempsey Posted September 29, 2011 Author Share Posted September 29, 2011 Thanks everyone. Yea I plan to do a couple of normalizing cycles, these dies will fit right in the hole in the top of my forge if I take the lid and plug of ceramic fiber out of it, so I'm just going to put them on there while I'm forging tonight, and switch them out to cycle. So do we think 5gal of canola will be sufficient, or should I try to up it to 6-7 just to be on the safe side? Quote Link to comment Share on other sites More sharing options...
Stormcrow Posted October 1, 2011 Share Posted October 1, 2011 My quench was 5 gallons of commercial quench oil and it did ok. More volume would have made me breathe easier, though, so if you have a large enough container, I'd up the amount. The oil got plenty hot and bubbled. More oil will cool it better. Quote Link to comment Share on other sites More sharing options...
Patrick Nowak Posted October 2, 2011 Share Posted October 2, 2011 For something as small and simple as this, it might be worthwhile to sent the job to a commercial heat treat shop. They will be able to heat the full component and quench in the proper volume of liqiud. When I was dealing with a commerical heat treater years ago, they chargeded by the pound and had a $20 minimum order. For small jobs like this, you likely won't even get to a price per pound fee but will just have to pay a flat amount. If you have a lot of time and machine work into the dies, you really should consider this option. Patrick Quote Link to comment Share on other sites More sharing options...
Javan C.R. Dempsey Posted October 3, 2011 Author Share Posted October 3, 2011 Yeah, I probably could get it done commercially, but I won't. I'm keen on the exercise, since I've never HT'd anything this large before, and I'm not obsessed with 100% perfection on this as much as learning how to do it myself. I normalized the dies after grinding them on my belt grinder last night. I didn't have any trouble getting them up to non-magnetic stuck in the top of my forge while I worked on other projects. After they got up to a good uniform color which probably took about an hour, I just cut the forge off and let all of it cool together. A 100lb pull magnet wasn't getting any traction, so I feel like I must have passed the curie point through most of the die itself. I'll probably go with 7 gallons of canola, which is a very fast oil. I think that'll get me acceptable returns. Quote Link to comment Share on other sites More sharing options...
pkrankow Posted October 4, 2011 Share Posted October 4, 2011 Do one die at a time, that way your volume is more appropriate. Phil Quote Link to comment Share on other sites More sharing options...
Javan C.R. Dempsey Posted October 4, 2011 Author Share Posted October 4, 2011 Aye definitely Phil. I'm only set up to heat one die at a time anyway. Quote Link to comment Share on other sites More sharing options...
Javan C.R. Dempsey Posted October 17, 2011 Author Share Posted October 17, 2011 Just wanted to update here in case anybody wanted to verify that I didn't kill myself. I HT'd these dies last week and appear to have been successful. I slowly heated these with the working part of the dies suspended in the top of my vertical gas "damascus" style forge, which after taking the lid off, had just enough inside circumference to take the die but seal the top with the plate the die is welded to. I just left them in there with the blower and gas choked real low but with as much of a reducing atmosphere as I could get guesstimate. I only normalized these once, since I didn't do very heavy grinding and it took a very long time. I was able to get them over non-magnetic and hold them for a while, and the dies were showing good deep color and the plates were showing good dark reds. I quenched in 5 gallons of canola, heavily agitating up and down, and once they were cool enough not to set the top of the oil on fire, I moved them to a big 10g of water or so. My house oven would only go up to ~600, so I tempered two cycles at 600 for 4 hours each cycle. I had very light scale, and the hardness appears to be good. A heavy blow from a sharp corner of my peen will put a small dent in it, but working cold metal on the bull didn't seem to phase them. We'll see how they hold up, but hopefully, I'm good. Thanks for all the advice guys! Quote Link to comment Share on other sites More sharing options...
thingmaker3 Posted October 25, 2011 Share Posted October 25, 2011 The specific heat capacity of canola oil is just over 1.9 Joules per gram per degree Celsius. The specific heat capacity of steel is just under 1/2 Joules per gram per degree Celcius. Quenching 5 1/8 kg (11.5lbs) of steel at 870 C (1600 F) into 17 kg (5 gallons) of canola oil at at 38 Celcius (100 F) should yield quenchant and steel at about 99 C (210F). (This assumes an adiabatic environment, which will not be used in the real world. Actual temperatures will be a smidge cooler.) I have no data on specific heat capacity or density for Parks #50. Quote Link to comment Share on other sites More sharing options...
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