View Full Version : Heat treating and oil quenching

June 16, 2009, 10:00 AM
I know that when you parkerize something, in order to get the most corrosion resistance, you need to heat it up alittle and cover in oil or grease so that the open pores soak it up.

So by that line of thinking, would quenching in oil (rather than brine or just plain water) give any corrosion resistance to small parts that you'd not give a regular finish (ie, sears, breech blocks, small internals)? Or would it just sweat it all out during the tempering process?

June 16, 2009, 10:07 AM
in oil (used motor oil) as I understand it, the red hot metal upon being quenched, absorbs/attracts the carbon present in the used oil, thus hardening the metal being quenched.... but nothing to do with corrosion prevention, just hardening due the the addition of carbon.

From what you say about 'parkerising' to me it would make sense to quench harden first, then as a finishing process, possible corrosion prevention, warming and greasing might work, but eventually this grease would be worn/washed off so I would say regular rust prevention as usual for iron/steel objects would still be neccessary?:D

June 16, 2009, 01:18 PM
Oil has a higher boiling point and specific heat than water.

Oil hardening steel is a different alloy the water hardening steel.

It has nothing to do with absorbing carbon from the oil, but everything to do with heat transfer speed.

June 16, 2009, 04:38 PM
To further confuse the issue,the typical unsheilded torch heat and dunk method will usually produce a few thousandths of surface decarburization

Likely,if you want a nice hard surface,plan on grinding or stoning a bit,assuming you are working with an oil hardening tool steel.And you will want to draw(temper ) it some.O-1,for example,is rather brittle as quenched.

June 17, 2009, 09:24 AM
Specific steels are best quenched with what they are recommend for by metallurgists.

O-1 should be quenched with "quenching oil", not water, not used motor oil.
W-1 should be quenched with water (actually brine, brine controls bubbles insulating the metal from the quench).

Note: W-1 and O-1 are both brittle as quenched and should be drawn (following manufacturer's directions), immediately upon quenching.

Using anything else will result in unintended results. If you have not studied metallurgy, follow the directions from the manufacturer of the steel, or metallurgists. Uneducated people's folksy suggestions should be assessed as to worth by how much they actually cost (usually free). If you needed brain surgery, would you consider the advice of a person with a beer in their hand, or that from a brain surgeon?

June 17, 2009, 12:07 PM
I thought of writing a long post going into some of the details of how this works, but there is a lot to cover. I recommend you get one of the many books on topic and read it. This page (http://www.knifenetwork.com/workshop/tut_heat_burnett.shtml) has some useful tips. So does this one (http://anvilfire.com/FAQs/heattreating.htm). And some information that is alloy specific is here (http://www.evenheat-kiln.com/technical/knifetech/knifetech.htm).

June 17, 2009, 12:20 PM
I used to spend a lot of time collecting and restoring old woodworking tools. Every once and a while I would get something that had lost it's temper, someone usually has overground a chisel or plane blade at high speed and caused the material to become too soft.

When a tool was made in the 1860's, its nice to get it back into shape instead of tossing it. So it was up to me to fix these and I did a lot of research into hardening and tempering. In the end, it turned out that the process was pretty simple and pretty hard to screw up. The biggest mistake you could make was to quench O1 steel in water (or brine). It warps the heck out of the tool. IIRC, W1 steels can be quenched in oil, they just may not harden as well. Often, however, it is hard to know what type of steel you are using so I always used oil, just to be safe. I never got the hang of the spark test. But I never ruined a single piece.

O-1 should be quenched with "quenching oil", not water, not used motor oil.

Peanut oil works the best. Smokes very little, rarely catches fire and has a nice scent.

June 17, 2009, 02:24 PM
I used Amerline parkerizing solution, and they gave you a bottle of "seal" that you sprayed on while the parts were warm as they came out to the tank.

Any sort of heating other than the temperature of the solution will probably make parkerizing turn a bunch of different shades.

James K
June 19, 2009, 07:05 PM
Parkerizing is simply a phosphate coating, usually applied by boiling the finished (and already hardened if necessary) part in a water-based solution. Like tank bluing, it has nothing to do with hardening the part and the heat required is not, and should not be, enough to do that.

The original purpose of Parkerizing is to hold oil and thus prevent rusting. Only secondarily is it used to reduce or prevent glare on military weapons.

Sealing Parkerizing prevents it from soaking up oil, and eliminates one of its reasons for being applied in the first place.