Spring Steel and Heat Treating

[Elite Armory]

I have a few questions that may or may not be possible to answer over the internet but I thought I'd try anyways...

I have a strip of steel that I got from a Steel yard and the worker that I got it from said that it was a high carbon spring steel. This strip was from a big roll that he said they use to wrap up pallets with. He cut it from a big roll of black steel that is about 1mm thick and about an inch wide. If anyone is familiar with what I'm talking about, do you know if this is indeed high carbon spring steel?

I'm not that experienced at making springs as I have only made a few so far but when I tried to use this material to make a hand spring, it didn't react like the other steel I've used and know is high carbon steel. I cut and bent this steel to shape, then I heat treated it by torching it to a cherry red and quenching it in motor oil, then I cleaned it off with fine sand paper and heated back up to a blueish color and let it air cool. Now what happens is it then looses all of it's springiness. It was actualy more springy before heat treating it. After I heat treated it, when I try to flex it, it just kind of breaks but doesn't really break. It's hard to explain but it kind of snaps in a line and is weak at that line but does not actually break apart. It pretty much looses all of it's springiness and just crunches a spot and stays there when I try to flex it.

I know this maybe hard or impossible to tell over the internet without seeing it but does anyone know what is going on? Does it sound like my heat treating process is wrong or is it the steel that I'm using? Any input or ideas would be greatly appreciated.

 

[FTG-05]

Your heat treat sounds about right and I know what steel you're talking about. For that application, I see no reason why that steel would have to be any version of "high carbon". That application just does not warrant high carbon tool-type steel to do it's job i.e. it's doesn't need to be particularly hard or "springy". Basically, it's just strapping.

But this does serve as an excellent example of why it's smart to use a known steel vs. scrap or unknown version. Known high carbon steels are fairly cheap, depending on quantities and type, from places like McMaster et al. Is there some reason you can't buy what you need from there or was this just an experiment to see if you could use this steel?

Good luck.

 

[ronnie gore]

spring

i have had a blacksmith shop for 30 years to make knives, and i have made several springs. if you know for sure what the scrap steel is you can harden and temper it.
it is better to buy a known source of steel , brownell's has lots of spring stock. but i will tell you those small spring are a lot of trouble.
what the steel you were using sound like is banding which is a medium or low carbon steel.

 

[Elite Armory]

Thanks for the help. The reason I tried to use this was because I just went to the steel yard to try and find some high carbon steel that I could use and they didn't have any but one of the workers gave me this piece and said it was high carbon spring steel so I took his word for it.

I noticed Brownells does have what I need but was hoping not to have to pay $45 + 12.95 shipping for 10 - 16" pieces since I don't need that much of it.

Is there a cheaper place to get it from? What is McMaster et al (I tried googleing it but nothing came up)?

 

[ronnie gore]

spring

try some machine shops they have a lot of scrap pieces and they will know what type steel it is. also try clock repair as they have old springs , on your heat treat preheat the oil to 125 degrees before quenching and only bring the steel up to the critical temperature for quenching, that is when the steel become non magnetic it is perfect temperature for quencing in 125 degree oil, the steel will become very hard then bring it down to the correct temperture for tempering and temper twice to relieve stress.

 

[Elite Armory]

try some machine shops they have a lot of scrap pieces and they will know what type steel it is. also try clock repair as they have old springs , on your heat treat preheat the oil to 125 degrees before quenching and only bring the steel up to the critical temperature for quenching, that is when the steel become non magnetic it is perfect temperature for quencing in 125 degree oil, the steel will become very hard then bring it down to the correct temperture for tempering and temper twice to relieve stress.

Thanks for the additional details on the heat treating. I didn't know you were supposed to temper twice. What happens if you only do it once? What is your method of bringing the oil up to 125 degrees?

 

[ronnie gore]

temper

temering twice just insures that all the stress has been relieved. i quench in a 5 gal bucket of 10 weight oil and bring the oil up to temperature by heating a jackhammer bit in the forge and putting it in the oil, becareful the oil will ignite. you don't have to use that big of a container i just do because it gives me the length i need for long blade.

 

[WR Moore]

I'm getting somewhat confused by some of the terminology used here. "Critical temperature" has specific meaning for heat treating steel and it's waaaay beyond the temperature needed to temper steel.

Real briefly, heat treating involves two processes: hardening and tempering. To harden steel, it's heated to its critical temperature that varies somewhat according to steel type (it's been a long while here), but you're basically talking well over a thousand degrees to produce the physical changes necessary in the steel. The steel is then quenched by various means to harden it.

The second phase of the process is drawing or tempering. Here, the steel is heated to a very narrow temperature range (usually much less than 1000 degrees) to produce the final hardness desired and then quenched (air, oil or water) as required. Yes, the proper temperature is needed for the specific steel qualities you might want, but it's really not the "critical temperature".

Brownells Kinks books have several excellent sections on heat treating and making springs. You might want to check them out. The printed catalog used to have temperature charts for the various hardness levels too.

I do agree steel banding just isn't the right type for a spring. While Mythbusters may have proved it is possible to polish dung, you can't make a spring out of it.

 

[FTG-05]

Thanks for the help. The reason I tried to use this was because I just went to the steel yard to try and find some high carbon steel that I could use and they didn't have any but one of the workers gave me this piece and said it was high carbon spring steel so I took his word for it.

I noticed Brownells does have what I need but was hoping not to have to pay $45 + 12.95 shipping for 10 - 16" pieces since I don't need that much of it.

Is there a cheaper place to get it from? What is McMaster et al (I tried googleing it but nothing came up)?

O1 Tool steel from McMaster-Carr (page 3671 if the link doesn't go directly to it): McMaster-Carr

They have other types of tool steel, but O1 is probably the most forgiving of steels for your level of experience.

Knife Kits also has knife/tool steels.

If you're really interested in using scrap-type steel, then see if you can find some leaf springs, they are *usually* made of 5160 steel, which is hardenable and relatively easy to work with.

Good luck.

 

[Tyrod]

If you're really interested in using scrap-type steel, then see if you can find some leaf springs, they are *usually* made of 5160 steel, which is hardenable and relatively easy to work with.

Yeah the leaf spring out of a Deuce and a half ought to last ya a day or two.