FrankA Posted July 25, 2011 Share Posted July 25, 2011 For a while now I am trying to harden 4140 for use under the power hammer. I use 3/4 x 3 x 8 blanks that I bought for a blacksmith magician. I forge them to shape, soak them in my propane forge (with a little excess propane to not produce scale) for an hour, quench and then temper. For quenching I tried old motor oil first and for tempering my wife's kitchen range (400 F). The resulting tool did not hold an edge for butchering one tenon and the end mushroomed. I later heard that motor oil is no good and changed to 3 gallons of canola oil: Same result. Then I added 1 third Diesel fuel to my canola oil to reduce viscosity: still not hard. Finally I thought, even if it cracks: lets water quench. It did not crack, but the resulting tool was very soft again (for tempering this time used a knife makers kiln at 400 F. My tool, a feather swage for power hammer use had lost its nice surface after one leaf. Quote Link to comment Share on other sites More sharing options...
monstermetal Posted July 25, 2011 Share Posted July 25, 2011 Sounds to me like it's not 4140. How did you come by the material? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 25, 2011 Share Posted July 25, 2011 Most folks with a long term history of buying metal have a tale to tell of an order that was "mis-filled" and what they got wasn't anything like what they originally ordered. Anyway you could have it analyzed? Quote Link to comment Share on other sites More sharing options...
MattBower Posted July 26, 2011 Share Posted July 26, 2011 I second the question. What temp were you quenching from? Quote Link to comment Share on other sites More sharing options...
FrankA Posted July 26, 2011 Author Share Posted July 26, 2011 I quenched it from the same heat I usually use to forge. Yellow with a bit of orange in it I would say. Quote Link to comment Share on other sites More sharing options...
Backwoods Blacksmith Posted July 26, 2011 Share Posted July 26, 2011 Way too hot. use magnate to check for critical temp Quote Link to comment Share on other sites More sharing options...
MattBower Posted July 26, 2011 Share Posted July 26, 2011 That is too hot, at least according to my calibrated eyeball's estimate of yellow-orange, but it doesn't explain why the steel didn't get hard. I too am starting to wonder if your 4140 isn't 4140. Quote Link to comment Share on other sites More sharing options...
monstermetal Posted July 26, 2011 Share Posted July 26, 2011 Yep... you really have to be suspect of material... even if you think the supplier is reliable. I have bought a lot of stuff that was marked and ended up not being what it was marked... Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 26, 2011 Share Posted July 26, 2011 One aspect of getting off marked steel is that every mill/dealer usually has a different set of marking colours so if "yellow" from dealer/mill A is 4140; Yellow from dealer/mill B might be 1020. The problem is when you have re-seller C that has steel from both A & B and may have their own marking system to boot. Confusion oft doth occur! Quote Link to comment Share on other sites More sharing options...
FrankA Posted July 26, 2011 Author Share Posted July 26, 2011 I got the blanks from Blacksmithjournal together with a smithin magician a couple of years ago but never used them until now. Quote Link to comment Share on other sites More sharing options...
MattBower Posted July 26, 2011 Share Posted July 26, 2011 I think someone sent you the wrong steel. I don't see another explanation. Quote Link to comment Share on other sites More sharing options...
FrankA Posted July 27, 2011 Author Share Posted July 27, 2011 Thank You guys. That makes me feel a little less stupid. I will get new steel and try some more. By the way: What kind of oil do you use? Does it really matter for blacksmith accuracy? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 27, 2011 Share Posted July 27, 2011 Lots of us use warm vegetable oil, anything from used fry oil from a fast food place to peanut oil leftover from Thanksgiving's Turkey Fryer. Not in the league of a good engineered quenching oil like a parks 50 quench oil. We generally advise against used motor oil as it's fairly contaminated with nasty stuff Some folks use clean ATF. Quote Link to comment Share on other sites More sharing options...
Spears Posted July 27, 2011 Share Posted July 27, 2011 I use old crankcase oil for my power hammer dies and have had good usable results. I temper in a small oven at just about 400 deg F for 1-1.5 hours per cross sectional inch. You can not overtemper a part so lengthen the time as opposed to shortening. I fixture the part in front of the mouth of my gas forge and try to ramp-up to temperature +1600 over say 20 minutes. Thinner things like blades which have great value needing superior integrity throughout should use the best quenching medium money can buy. Thick power hammer dies used for shaping and texturing can get away with using less strict processing methods and still get pretty good results. Without "checking" it you'll probably end up with Rockwell 45-50 C scale using 4140 quenched in oil long temper session ~380-400 deg F. I use a tub of ~17 gallons for a maximum of 2 dies per session weighing in at ~5 lbs each. Good luck. Spears Quote Link to comment Share on other sites More sharing options...
Jymm Hoffman Posted July 31, 2011 Share Posted July 31, 2011 A good resource I use from Crucible Steel: http://www.crucibleservice.com/eselector/general/generaltitle.html Quote Link to comment Share on other sites More sharing options...
KYBOY Posted August 31, 2011 Share Posted August 31, 2011 http://www.speedymetals.com/pc-1261-8313-34-x-3-4140-cold-finished-annealed.aspx I use peanut oil for slower quench steels and use fast quench from mcmastr carr for the faster steels..On the note of mild steel for tooling at times I will use mild steel and harden it somwhat in super quench..Ive had the same mild steel fullers in my guillotine for over two years and they have only started to show slight wear..i would stick with something tougher for a butcher though..Speedymetals sells 4140 in many shapes and sizes..Ive bought plenty from them..Though not real cheap right heres 3/4" x 3" 4140... Quote Link to comment Share on other sites More sharing options...
Tim S. Posted September 1, 2011 Share Posted September 1, 2011 It is possible that the material is wrong but I wouldn't rule out decarb just yet. Try taking a file to a hardened piece. See if the hardness increases as you go into the part. IF so = decarb, Quote Link to comment Share on other sites More sharing options...
nonjic Posted September 1, 2011 Share Posted September 1, 2011 Can decarb very deep, and I think the austentising temp might be very high (900c ish)? magnet and a very deep file test are your friends :D Quote Link to comment Share on other sites More sharing options...
gearhartironwerks Posted September 2, 2011 Share Posted September 2, 2011 For a while now I am trying to harden 4140 for use under the power hammer. I use 3/4 x 3 x 8 blanks that I bought for a blacksmith magician. I forge them to shape, soak them in my propane forge (with a little excess propane to not produce scale) for an hour, quench and then temper. For quenching I tried old motor oil first and for tempering my wife's kitchen range (400 F). The resulting tool did not hold an edge for butchering one tenon and the end mushroomed. I later heard that motor oil is no good and changed to 3 gallons of canola oil: Same result. Then I added 1 third Diesel fuel to my canola oil to reduce viscosity: still not hard. Finally I thought, even if it cracks: lets water quench. It did not crack, but the resulting tool was very soft again (for tempering this time used a knife makers kiln at 400 F. My tool, a feather swage for power hammer use had lost its nice surface after one leaf. Imho, 4140 only gets hard when quenched in water, and needs tempering at 325 deg for an hr per inch of thickness. That's not what the specs say, but that's what I've found works. Hammer heads, dies, whatever... Oil will not get it hard. Tempering beyond 325 deg will soften it beyond use. Rob Gunther says it can be hardened in super quench. I don't know as I haven't tried it. 4140 seems to me to be one of those border line materials that depending upon how you want to use/abuse it, there is a lot of latitude in processing. For most, it's a pretty forgiving material. I like it. JE Quote Link to comment Share on other sites More sharing options...
Jura T Posted September 2, 2011 Share Posted September 2, 2011 Imho, 4140 only gets hard when quenched in water According to this data sheet www.fordtoolsteels.com/pdf/LSS_4140-4142HT.pdf you can use oil for quenching. The quenching temperature for 4140 is quite a bit higher than the Curie (non-magnetic) point, so using a magnet for detemining the quench temperature does not work. Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted September 2, 2011 Share Posted September 2, 2011 Sorry John, not my experience at all. Most references warn "NEVER water quench 4140". Water quenching is usually avoided in sections smaller that 2". In tools up to 1 to 1-1/2" I've never had trouble getting low to mid 50's Rc as-quenched and 46-48 Rc after 400 draw. Quote Link to comment Share on other sites More sharing options...
MattBower Posted September 2, 2011 Share Posted September 2, 2011 I don't have much experience with 4140, but I did do a hammer head out of the stuff. Hardened fine in oil. The point of all that chrome and moly is to make it deep hardening -- and deep hardening allows for slower quenchants. Quote Link to comment Share on other sites More sharing options...
gearhartironwerks Posted September 24, 2011 Share Posted September 24, 2011 Sorry John, not my experience at all. Most references warn "NEVER water quench 4140". Water quenching is usually avoided in sections smaller that 2". In tools up to 1 to 1-1/2" I've never had trouble getting low to mid 50's Rc as-quenched and 46-48 Rc after 400 draw. Grant Grant, I'll be happy to send you some "beater" hammer 4140 heads that did not harden in oil despite being heated to 1550 deg in a heat treat oven and quenched in 150 deg oil. Water is where it's at if you want to get 4140 hard. I don't care what most references say. I'm going with reality. I made a number of hammer heads using the "referenced" method, only to find they were soft. As a last resort, I went to a water quench, and 4140 finally got hard...w/no cracks. I feel that one has to go with what works for you. I'll take h2o. JE Quote Link to comment Share on other sites More sharing options...
forgemaster Posted September 25, 2011 Share Posted September 25, 2011 Just as a comparison we harden tons and I mean tons of 4140 over 3" thickness in water from about 870 deg C and retemper to 575 deg C and can always reliably get a hardness of 302 hardness brinell. I reckon it's not 4140. For the app you describe I would tend to find 4140 a little soft, I'd use 5160 (spring) harden from 850 deg C in oil, temper by heating till the oil from quenching flashes into flame. Phil Quote Link to comment Share on other sites More sharing options...
Nakedanvil - Grant Sarver Posted September 25, 2011 Share Posted September 25, 2011 Over 2", I agree completely with water. Even then it won't get very hard in the center. As I was trying to tell John, I agree oil won't do it when you get above 1-1/2 or 2 inch. Which I believe is right where he's at unless he's making awful small hammers. Plus austenizing at 1600º as Phil is doing in important too. I've made thousands and thousands of tools from 4140 and never have trouble getting full hardness in oil. But just like the original question in this thread I'm talking less than 1" thickness. Quote Link to comment Share on other sites More sharing options...
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