Thread of Oct. 11th under shoptalk.
Topic: Heat Treat BG42
posted 11 October 1999 12:05 PM
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Anyone know the recipe to heat treat BG42? TIA
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Kevin Wilkins
Senior Member
Posts: 170
From: Berlin, GERMANY
Registered: Oct 98
posted 12 October 1999 03:30 AM
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Can't find my spec shet but you can get one from Latrobe Steel under:
724 537 7711
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www.wilkins-knives.com
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rj martin
Senior Member
Posts: 181
From:
Registered: Oct 98
posted 12 October 1999 10:50 PM
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Try this:
Austenitize at 2050 in HIGH temp foil for 20 minutes.
Air quench.
Temper at 975F, 2 hours.
Liquid Nitrogen Freeze for 24 hours.
Temper at 975F 2 more times, 2 hrs each.
Finish hardness, Rc61-64.
Most likely, you'll get 60/61
RJ Martin
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Rob Simonich
Senior Member
Posts: 462
From: Clancy Mt. 59634
Registered: Oct 98
posted 12 October 1999 11:04 PM
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Here is what my Latrobe brocheur says about BG-42, this is a short version.
Hardening and tempering: Preheat to 1550, Austenitize at 2050. Oil quench to room temp or salt quench at 1050, then air cool to room temp. Stress relieve at 300 for 1 hour then air cool to room temp. Refrigerate at -100, then warm to room temp. Double temper at 975 2 hours each cycle. Resulting hardness 61 to 64.
I dont do much like they do, they are talking about bearing size pieces that have a bigger cross section than knifemakers normally use. OK, so at the risk of catching a lot of hell, (which wont bother me anyway) here is my current profile for heat treating BG-42, subject to change with further testing.
Preheat to 1500, hold for 20 min, ramp at 2500 deg per hour to 1990, soak for 30 minutes, one blade per package. Take blades from furnace and immediatly lay blades on 6X18" surface grinding magnet turned on and place a 6X18X1/2" thick steel bar over the blades. (some call this a press quench. This cools the blades very quickly and they are STRAIGHT when quenched. After removing from the magnet, stress relieve for an hour at 300. Then place into LN, or dry ice if that is all you have, for 6 to 8 hours, the blades at this tiome will test around 64 to 67 Rc. After freeze treat, temper at 500 for 2 hours, 475 for 2 hours, and 450 for 2 hours, resulting hardness is Rc 61 or so. Remember the high temp low temp argument with ATS-34? In my LIMITED experiance, same goes for BG-42. In my shop this heat treat is much better than Latrobes for knives.
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www.simonichknives.com
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Osbourn
Senior Member
Posts: 122
From: Middleburg, Fl.
Registered: Jun 1999
posted 13 October 1999 12:18 PM
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Rob, with that press quench that you mentioned, the magnet and plate are basically heat sinks for the quench, yes? What kind of affect does this have on the crystaline structure? I'm guessing that it makes for smaller crystals than just the straight air quench because of it being more violent, and the pressing is what prevents warpage. Is this guess close?
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Oz
"When your work speaks for itself, don't interrupt."
- Henry J. Kaiser
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jeffj
Senior Member
Posts: 143
From: Jonesboro, AR
Registered: Apr 99
posted 13 October 1999 02:32 PM
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Is it possible to use just two pieces of steel and a clamp for a press quench?
jj
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thknives
Member
Posts: 10
From: Calgary, Alberta, Canada
Registered: Jul 1999
posted 15 October 1999 09:55 PM
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Am I missing something, or does the heattreating foil melt at 2000 F?
The other question I have is regarding the plate quench, obiosly this is only for blades that do not have tapered tangs, or they would not be centered corectly anymore.
Rob, the heat treating RC you listed make no sence.
BG 42 has secondary hardness caracteristics, as does ATS 34. As quenched hardness is usually around RC 61 - 64.
If you end up with a RC of 64 -67 as quenched and temper at 500 F you still have a RC of 64 - 67. You would have to temper above 950 F to drop to the 61 RC you listed.
This would also mean that if one reaches the secondary hardening stage your RC would be as high as 70?
Something does not seam right, can you please elaborate.
I do my own heat treating of BG 42 in a saltbath furnace. The formula I use goes as follows:
Austenice at 2050 F for 23 min.
Quench in salt at 390 F, aircool
Rampcontrolled LN for 36 hrs, not a chance of stress cracks there, as the blades are never immersed in liquid N, and slowly cooled and warmed up.
Triple Temper at 400 F for 2 hrs each.
RC as quenched 61/62, RC as tempered 62, tested by local heat treat shop to varify RC.
Every blade I did todate tested the same RC.
http://members.home.net/thknives
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[This message has been edited by thknives (edited 15 October 1999).]
