CHPerdue Posted March 17, 2012 Share Posted March 17, 2012 I will be hardening my DIY air hammer dies.They are H13 2x2.5x6 I figured I'd ramp pre heat the dies to 1100 F and soak 2 hrs they take they up to 1800 and hold for an hour. Then oil quench to 700 F then air cool to 135 and temper at 900 for 2 hours. They are mounted on 1/2x6x6 plate and welded with 10018 rod. This will be my first time at doing dies or any thing near this large. Does anyone see a problem with doing this. I could flood the furnece with argon to help reduce decarb but if I don't need to do this then it would make life easier not to mention cheeper. I have about 12 gal of quench oil, I would like to do top and bottom at the same time if that is enough oil? Each die and plate is about 18 lbs. Is cracking going to be a problem? How about the welds? Do I even need to heat treat the dies being H13? They are anealed after welding. Thanks and HH CH Quote Link to comment Share on other sites More sharing options...
HWooldridge Posted March 18, 2012 Share Posted March 18, 2012 My power hammer dies are H13 and yes, they do need to be heat treated from an annealed state or they'll get marked up quickly. Re the decarb, you can use SS foil - it's pretty cheap. Toss a bit of paper or cardboard inside then roll the seams, the paper will char and keep out most of the O2. Cracking might be a problem if you have any sharp inside corners and the pieces aren't stress relieved first but it sounds like you welded to plate. H13 will air harden but I can't recall at what point you need to use oil. I am guessing but 12 gallons of oil sounds like enough; you will definitely put a lot of heat into the fluid. Be sure and draw the dies 2-3 times; you are going to want something around 48-50 Rc with no stress risers to cause cracking. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted March 18, 2012 Share Posted March 18, 2012 Did you get your specs from the steel makers? I have an old "Bethlehem Tool and Die Steel Manual" with their ideas. For hardening, preheat to 1350F and soak. Then, heat to 1850F and hold one hour per inch of greatest cross section. The booklet recommends quenching in still air and tempering immediately. Oil can be used as the quenchant, "but keep in mind that when oil quenched, this grade is as vulnerable to cracking and has the same distortional characteristics as an oil hardening steel." As for tempering, I quote, "For improved shock resistance, the steel is often tempered at temperatures approaching 1150F resulting in hardness of HRC 40 to 44. The steel should be held at the tempering temperature for at least two hours per inch of greatest cross section. All hot work steels should be tempered at a minimum of 50 degrees above the expected maximum operating temperature of the tool or die. Double tempering, with the second temper 25 to 50 degrees lower than the first temper is always advisable, particularly where heat checking is a problem." I can't speak to the arc weld except to say that in general, tool and die steels do not take kindly to fusion welding. Quote Link to comment Share on other sites More sharing options...
macbruce Posted March 18, 2012 Share Posted March 18, 2012 I'm no expert on this but I've always had good luck air hardening h13....far less drama ;)....There are professional heat treating outfits in Denver that are quite reasonable I've heard......If you have any leftover pieces of material try the air quench...... Quote Link to comment Share on other sites More sharing options...
ciladog Posted March 18, 2012 Share Posted March 18, 2012 Frank has it correct. Stay away from the oil and quench in STILL air. And it is critical to temper immediately.You can weld H13 successfully if it is held at about 1000 degrees F. I make my hammer dies from H13 and have never had a weld crack. I have everything ready to do the welding while I am tempering. When they come out of the oven, I do the welding and let them cool slowly. Quote Link to comment Share on other sites More sharing options...
CHPerdue Posted March 18, 2012 Author Share Posted March 18, 2012 Hi All. Ok, so the oil quench is a bad idea? I read some place that on pieces thicker than 1" cross section should be oil quenched to get full hardness through out. Because of the mass of the die will not reach full hardness do to the long quench time? I have the SS foil and can wrap it with some papper in side. to help with decarb. I found a spec sheet that said you can air quench up to 60mm(2.36") so that may work? I'm worried about the 1/2" plate holding heat or causeing a problem? I Did weld it at about 1000 F so I did that right. I used 7018 for first pass and 10018 for the other 2 passes. I stress releaved at 1100 F and slow ramp down in the furnce. I will temper 3 times to take care of any carbide boundaries. The spec sheet I have lists H13 as quenched RHC 49-50, from 1850 F, tempered at 950-1250 F. Frank: Thanks my old friend, You was my first teacher and I have always relied on ever thing you tought me. I still have and use the S7 chisel we made in class. Thank you Master Turley. Ciladog: Do you weld the dies on the 1st or last temper? I have already welded my first set of dies, before heat treat. I have another set that I plan to make combo dies out of. Hardening first sounds like the way to go KISS. HWooldridge: Thanks for the SS foil tip, I'll use it. McBruce: We have a Heat treat shop in Colorado Springs, I may just take the other set of dies to them if I flub the dub on this set. I think I will try the air quench and 3 tempers and see what the result is. I have a backup set if needed. I have looked at several other h13 heat treat sheets and they all have a little different process. Just KISS sounds like the best way. Thanks all CH Quote Link to comment Share on other sites More sharing options...
ciladog Posted March 18, 2012 Share Posted March 18, 2012 I weld them up on the last temper. Quote Link to comment Share on other sites More sharing options...
Jymm Hoffman Posted March 20, 2012 Share Posted March 20, 2012 The heat treat facility that do my anvils is so good, I send stuff like that to them. It is not worth the by guess by golly. It took me about 6 or 8 tries to get 2 good hammer heads in H 13. It is very sensitive to getting the temperature right for the right time, etc. I think you chose the right material for your dies. I have dies from different steels and a couple of the same pattern as the H 13. The H13 is holding up better than S7, or 4140, after several thousand parts. I had the heat treaters temper my dies to around 50 Rockwell C. I make spring dies and other hand held tooling from 4140 and some times A 36 for a real quick short run. I don't bother heat treating the spring or hand held tools, just keep them cool when using. Quote Link to comment Share on other sites More sharing options...
gearhartironwerks Posted April 6, 2012 Share Posted April 6, 2012 Actually, Grant Sarver suggested heating to 1950 deg for 2 hrs, quenching in warm oil, then tempering at 1050 for 2 hrs. I've made many hot working tools, especially punches, and he was spot on. You really need a heat treat oven when working h13. John Quote Link to comment Share on other sites More sharing options...
CHPerdue Posted April 7, 2012 Author Share Posted April 7, 2012 Hi John I saw that from Grant but every one said to air quench??? I do have a Heat treat oven with ramp/soak PID controler. It has 2 240 volt coils and is made from k2300 soft fire brick 3"x9"x4.5" with stainless skin. The air quench seems to have worked. I Tempered them 3 times at 1050 F for 1hr/inch thinkness. I file tested a corner and they seem a little soft to me. Not sure yet if they will work, figured they would be harder. I use the stainless foil and papper inside, that worked great for scale. I can anneal them, and do over if need be. Think the dies are so thick and they take for ever to to cool to 150 or so, just not sure they cool fast enough to harden all the way.I know they are softer than my PW anvil face. HH CH Quote Link to comment Share on other sites More sharing options...
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