Simple Hardening Question

R

ritzblitz

Joined
Dec 31, 2006
Messages
293
I have a simple question here for you guys.

Today I decided to try and make a cut off hardy from a rail road spike. I ground it to a nice edge and then quenched it in motor oil. I figured it was pretty hard so I hit it with a hammer lightly to see if the edge would mash down. It did. This was without a temper.

First question-
I figure motor oil is a terrible quenchant. What should I be using?

Second Question-
Is the temper what prevents something like this from happening? Is it all just because of the motor oil?

I also forged a small chisel and performed the same triple quench. This time in water. I beleive the steel is something like 303 ss although I am not sure as it is just scrap from work. I went to shave metal from a peice of softer steel and the edge just bent over.

Any simple reason why this happened?

Sorry for the stupid questions, I probably should have experimented further.

Thanks guys.

Alex
 
RR spikes are low to medium carbon and not very good steel for a cutting tool but try water. Motor oil no good either, get some quench oil. 300 stainless will not harden. You need to get some good high carbon steel and read up on steels and heat treating. :)
 
The purpose of hardening is to keep the steel in shape. Specifically the edge and the sharpness. It, as the name says, hardens. The temper is to return or back off the hardening to give it some spring, otherwise your steel with be brittle and snap. Thus, when you see that someone hardens their steel to 65 rockwell and then tempers it to 59, they are softening it just slightly to prevent breakage. Hope this helps.

Erik
 
I've heard of using transmission fluid for a quenchant. Does this work well?? If so, which type should I get? Any specific brand availible at Pep Boys or Auto Zone or something?

As for steels, I have been forging these scrap cut offs from work which are extremely red hard. They are a pain but I figure it's good practice. Too bad I have no idea what type of steel it is...

Thanks for the help there Don.

Alex
 
Are you using a high carbon RR spike, or a regular spike? The high carbon type is embossed with an HC on top. Just checking, didn't want to simply assume.
 
Even with the HC mark the carbon content is still only mid range - 50 points typicaly IIRC.
 
These spikes don't have the the HC mark as far as I know.

Any advice on a readily available quenchant?

Thanks.

Alex
 
I thought they 35 points. The only good use for a regular spike is in a cross tie. The only way to harden it, is to case harden it. Even the so called high carbon spike will not make any thing close to a decent knife.
 
If you want to harden HC spikes as best they can, google "SuperQuench recipe".
 
1) Perform a spark test against known steels to evaluate, at least roughly, the carbon content of your rr spike. It may vary from low to medium.
2) Motor oil comes in various grades.
50w90 transfer case oil is too thick.
I used 15W40 heated to some 40 °C to quench C70, and worked, but was still too mild as a quenchant.
5w30 is better (but is expensive...)
You can also mix motor oil with ATF or hydraulic fluid, but I prefer to stay away from mixes. If I can't find graded quenching medium, at least proper oil is graded as well, and I can, with trial and error, find a good one and compare one with another.
Today I quench W1 and W2 in hydraulic fluid.
It flares up pretty well, so you have to be quick and submerge all the blade. Or, if you want a differential quench, do it outside and use long pliers.

Quenching harshness needed to obtain a proper hardening depends both from the steel you are traying to harden, and the section.
Leave the edge of your anvil tool at least 0.05 to 0.1 inches thick, least you crack it trying to peroperly harden the tool big section.
You must quench such a big piece in water or, if mild steel, in Super Quench if you want to obtain at least a little hardening. Oil is too mild on such a mass of steel.
 
They can be used, but what you have to do is match your quenchant to your steel. If what you want to do is harden normal railroad spikes as hard as they can get (still not that hard in most cases) you will have to use water or something like the superquench furmula Fitzo mentioned.

For most modern tool and knife steels these quenchants are too harsh and an oil of somekind is used. For best and repeatable results commercial quenching oils are recomended and come in different quenching speeds to match to the steel. Alternatives can be used but with varying results, I prefer veggie oils over petroleum products like motor oil just because they seem more benign and there is no need to buy expensive olive oil as anything, like cheaper canola will work. Hopefully soon some commercial quenchants will become available to you average Joe with little hassle, but they are curently available through places like K&G, McMaster-Carr and Brownell's.
 
So what should I quench 1095 and 9260 in?

Also, is there any significant difference between 9260 and 5160?

Thanks!
 
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