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- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Heat Treating Questions
- Date: Sun, 29 Dec 2013 21:14:27 -0500
http://www.practicalmachinist.com/vb/general/heat-treating-questions-277601/
Thread: Heat Treating Questions
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12-29-2013, 12:10 PM #1
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- Mar 2013
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- Oshkosh, Wis. rauchle@ntd.net
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Heat Treating Questions
I heat treat small parts from time to time and after doing a fair amount of research, I have a few questions. This pertains to de carb of the surface whether case hardening or general heat treating. I have a 3/16" hole thru one of the bricks on my furnace and I would like to insert a 3/16" OD SS tube thru it and into a closed, stainless vessel that contains the parts to be treated. Thru this tube, I'll pipe in Argon at a low flow during the process thereby reducing exposure to oxygen. Some of these parts also have a reamed hole that I don't what deal with carbide reamers afterwards as a second process and investment. Can I insert a close fitting brass rod in the hole during heat treat to again minimize de carb? Thanks in advance.
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12-29-2013, 12:24 PM #2
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- Dec 2009
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- South Yorkshire, England.
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I have heat treated carbon steel in molten table salt. There was no discoloration even to a ground finish part.
Steve -
What kind of material are you treating?
I was looking into using a setup like this for 4140 just to get rid of the 200 dollar roll of stainless foil every time we do pins. So I will be watching this one.
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12-29-2013, 12:36 PM #4
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1. 330 stainless is about the only material that will withstand repeated heat treat cycles.
2. Unless you can figure out a way to pre-heat the argon, the cold gas will sit at the bottom of the chamber. I think that you'll be continuously cooling the parts.
You need an atmospheric furnace or just get some anti-scale compound. If you don't want to buy a 25 lb pail, it's available from Enco, MSC, Brownells, and others. It will make your quench oil dirty, but works well.
PBC anti-scale and anti-pitting compound (25 lb. pail)
JR
BTW, how do you HT 8620, that needs to be carburized? -
12-29-2013, 03:54 PM #6
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BTW, how do you HT 8620, that needs to be carburized?[/QUOTE]
Well, like I said in my first post," case hardening and heat treating" I usually use the pack method. -
OK, for case hardening, you use this product. The knife makers swear by it. We used to use it all the time on mild steel
Cherry Red Instant Case Hardening Compound
You will get some decarb on the surface, but it gets HARD. You can get in smaller quantities from the places listed above. I'm not a big lover of 8620. Automotive uses a lot of it for driveline parts. The case gets very hard, but can be prone to cracking. As far as strength goes, once you get below the case, you drop to about 70KSI, or the same as 1045 and less than 4140. It does grind nice.
JR -
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12-29-2013, 07:28 PM #9
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- Oshkosh, Wis. rauchle@ntd.net
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I have not tried any of the applied pastes or anything like that, Have you tried it?
Originally Posted by MichaelP
Did you try using an anti-scale compound like ATP-641? -
Aside from the fact that 641 is for stainless, yes, we use it at work. IIRC, it's 304 that you use for tool steel. More expensive than PBC.
IMO, the ATP products work good, but, you have to be careful of the part once its coated. The stuff doesn't stick to a ground surface very well.
None of them are perfect.
JR
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- [machinist] Heat Treating Questions, Lawrence London, 12/29/2013
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