Shiloh Rifle Forums

So I have been wondering what the process is for pack hardening 4140. I know Shilo does it cause their receivers are 4140. 4140 typically is a through-hardening steel that is oil quenched and tempered to the desired Rockwell hardness. I have heat treated 4140 but have always oil quenched and have heard that water quenching 4140 could cause cracking especially in areas where there are sharp corners. This has always been a mystery to me how Shilo found a way to pull this off. I have color cased 1018 and 8620 and these come out pretty decent with good colors. I’m sure this is a proprietary technique that Shilo developed and so will probably never know. Just curious if anyone else has pondered this?

Have you ever thought to spell it correctly, it’s Shiloh….. not Shilo.

KW

Fully anneal first….

years of experience.....my guess.

want to case harden at home?

heat your small part. lock plate, hammer, after covering it with CASENIT hardening compound, Dixie Gun Works.
heat it to dull red, and then keep it at that temp for about 5 minutes. the casenit will bubble, turn black, and get red with the part.

then. prepare a bucket of clean water, put in a lot of potassium nitrate. CVS store or now the net. create a saturated solution.

then put a rubber tube weighted at the bottom and drop it in the water.

quickly quench the part while blowing on the other end of the tube till you turn red and out of breath.

You will get hardened steel and have some nice case colors to boot. try it and it works. Ken

I know 4140 was developed as a thru hardening steel and 8620 was developed as a case hardening steel. I read someplace that to keep the 4140 steel from hardening all the way thru that before quenching the temp is brought down to about 1250/1300 F. This keeps the core from getting as hard as the shell. I may be all wrong on this as I am not a metallurgist and I have never color hardened anything.

The scrap steel bin got real full until I found the right temperature combinations...

“The scrap steel bin got real full until I found the right temperature combinations...”
1325 F ?

Thanks for the reply Kirk - I suspected the Shiloh process involved some delicate balancing of the temps.

I will not spell Shiloh the wrong way again
I will not spell Shiloh the wrong way again
I will not spell Shiloh the wrong way again…

Lol!

Dang! Reminds me of having to stay after school let out and write stuff on the chalkboard.

when I write, my computer spell check says'
"You again!"

when I write, my computer spell check says'
"You again!"

Made some milling machine vise stops out of run of the mill A36 steel. Pack hardened, packed with crushed up Royal Oak charcoal in metal box, heated to 1650 - 1700 degrees F. and once temperature was reached soaked at that temperature for 4 hours. Let everything cool down real slowly in the furnace. Pulled out of the pack next morning, re-polished and repacked in fresh charcoal and put back into furnace - bring up to 1500 degrees F. until entire box and work is up to 1500 degrees F. temp. Remove from heat treat furnace, knock off the lid and dump directly into quench tank. Fairly decent colors, pictures don't do it justice - colors look much better in direct sunlight. Surface is as hard as glass, fine file just skips over the surface, probably about 60 on the Rockwell "C" scale.

One more photo

Don't know what depth of case is - just wild ass guess at somewhere between .010" - .020"