Case Hardening steel plates

BobSig

BobSig

Joined
May 6, 2011
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Hello I would like you to tell me how to case harden some steel plates. I dont know if there is anyone better to ask then knife makers.

These are going in my plate carrying vest and will be worn over my soft body armor.

The steel plates are just regular steel stock sheets. I think they are a one size down from 1/8 or they are 1/8 inch. They have been cut to 5x7 and slightly rolled for use as my side plates. I also have 2 bigger ones for front and back, also slightly rolled. I am going to use a propane weed burner to heat the steel. :nevreness:


This is what I think I am suppose to do:
Heat the metal till it "greys" and then put it in oil so the carbon bonds to the steel. Use black motor oil b/c it has higher amounts of carbon in it. - I was told not to let the medal turn orange b/c this will change and weaken the structure too much and ruin the metal.

:confused:
Which type of oil should I use?
How many times do I heat and dip it?
How long to submerge it for?
How hot to heat it and how to recognize temperature?


Some guidance from you guys would be great. The more direction I can get the better,:stupid: please explain it to me like I am a child...

Thank you
 
There's a lot of hokey advice out there for knives and knife hardening, some of which is just plain bad. But it probably doesn't hurt anyone if the knife isn't hardened correctly.

It sounds like you are talking about steel for body armor. I DO NOT KNOW how body armor should be treated. I bet you will get plenty of advice from other people with no experience in testing mild steel's resistance to penetration.

I DO KNOW THIS: if it were MY body armor, I'd want to be VERY SURE the advice was correct. If you ask, you WILL find people who are willing to bet your life on their opinion. Bad advice with knife hardening gives you a knife that dulls a little easier. Big deal. Bad advice in body armor modification might be a little more of a problem!

(For example, if it should be hardened, why is the manufacturer using mild steel rather than hardening an inexpensive carbon bearing, hardening steel? )

Where did this advice come from? And how do they know it's a good idea? Was it in side by side comparison testing, or some dude saying "I hardened mine and it stopped a bullet"?
 
If you're going to really wear this because there is a chance you may be shot at, why not buy a proper trauma plate?
 
Don't do this. Your life is worth whatever the cost is of purchasing something professionally made.
 
Yes you guys do make some good points, I will not be wearing this into combat The purpose of this is to be ready if it is ever needed, if stuff goes bad. Which I dont think it ever will but I like being prepared and Im having fun at the same time. I figure it is better to have these than have nothing so I want to make them the best I can with my limited abilities

The plates were made in a machine shop by a friend. And I know the steel is soft and wont stop too much, I have pistol rated kevlar underneath the steel plates. I was going to case harden one of the 5x7 and then take them to the range and compare the two.
 
Kasinit only goes a few thousanths deep per hour of heat, and if not tempered, it is brittle as deep as it goes. I would believe that a bullet strike would easily break the thin hard skin, think a glass like coating, and continue on as if the CH was not there. If you want deep case hardening, the plates need to be pack hardened in charcoal, which given enough time would allow full penetration of the carbon. But, the plates would then still need to be tempered, as they would be very brittle otherwise, and fragments of the plate might penetrate the kevlar with a projectile driving them. The pack hardening would be basicly the same as early blister steel used for high carbon tooling and knives. You would be better off starting from scratch with a blade steel of something between 1050, and 1075, and heat treated to resist puncture without fragmenting. Without researching, I would think 1050/60 steel. Just my opinion, but if it were me, and I was really serious, I would search out for military armor plate steel. The guess work is done, and that would be as good as it gets for your wants. FMJ rifle ammo is going to go through 1/8" soft steel like it wasn't there.
 
Thanks LRB for the info, ya I know that soft steel wont do much for a rifle round. I was hoping case hardening would provide protection by having a mix of hardened and soft steel. The core is the soft part of course. The outer hard layer, while it may shatter will take a lot of the energy from the projectile and the soft core thats backed by the other layer of case hardened steel would be enough to stop or slow it enough for the kevlar to finish stopping it. One of these days I will be getting some real armor able to stop rifle rounds. when I finally do this and test the plates all tell you all how it went
 
I looked into doing something like this a while ago and decided against it due to the cost of a large peice of good hardenable steel. I would suggest trying out case hardened steel on the range, would be fun to shoot and tell you if it does anything but weigh you down. I think it was DSG arms that had rifle plates pretty cheap, about 150 or so, and you would know they work instead of pretty questionable homemade plates. Sounds like a fun project though.
 
I used to shoot a lot of steel plates in testing procedures for exactly what you're talking about. My conclusion was that you need more than 1/8th of an inch for just about anything (I was amazed at what my muzzleloader does to tempered plate even with lead bullets), and it needs to be strong. Hardened and tempered steel (RC 60) is about 6 times stronger than mild steel... consider what happens in a bullet strike too, heat is generated, heat lowers the elastic modulus of the steel and makes it more ductile, and more likely to be penetrated...

Recommend cpm 1V for toughness and strength at elevated temperatures, S7 if 1V is not available, 6-4 Ti alloy STA would be cool too...

Very interested in your testing results!

Oh the other thing I learned was thicker is better... thicker armor means more bullet upset, more energy and momentum transfer... better off with 7075 t61 3/8" thick than 1/8" steel (same weight)
 
Unless you're a Mall Ninja, I wouldn't use case-hardened mild steel for armor plate. As has been said, the case hardening is only a couple of thou deep.

If you can't afford real SAPI plates (which are ceramic), I'd buy some AR400 armor plate, which is readily available. If you live near a gun range, they probably have some cutoffs you can have very cheaply.

http://www.chapelsteel.com/ar400-flatbars.html
 
Guys, he is a mortgage loan adviser - Maybe he figures that a lot of folks will someday be looking for him and wants to be armored?

Bob, playing around with body armor and such may make you feel macho, but in reality it is just silly. If a situation arises where you need that much protection, it will be too late to put on an armor vest.

If you have any real world need for body armor, home made plates and ebay vests are really a dumb option.

If you are one of those chaps who is positive that the world is going to he!! and Mad Max type situations are just around the corner......you are probably on the wrong forum. We make knives, not conspiracy theories.

Sorry to sound harsh, but you clearly know nothing about case hardening, and I suspect little more about wearing body armor.

All this reminds me that there was a fellow walking around the Celtic festival this past weekend wearing a full Imperial Storm Trooper outfit......and a kilt.
Most people thought he looked ridiculous, but maybe he was just being cautious.....in case "stuff goes bad."
 
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