Heat treating S7 coil spring

[windancer]

Looking for a simple way to heat treat S7 for punches.

 

All the results I read from Google talked about holding at temp1, then temp2..... then cooling 100 degrees at a time, etc.

 

Anyone have a simpler way to harden truck coil springs?

 

Tried taking from non-magnetic, quick dunks to black, then air cooling. I know one way that DOESN'T work :)

 

Dave

[SoCal Dave]

Hi Dave:  First, what happened with the hardening of the coil spring?  Did you quench it in oil or water?  How long did you let it soak above magnetic?  And, did you run the colors after hardening?  

[swedefiddle]

Truck coil springs = S7  ??????????? since when???????????

[jmccustomknives]

Try heat treating as if they were 5160.  As far as I know, air hardening tool steels have never been used for truck springs.

[Jim Coke]

Greetings Dave,

 

If it is spring steel... 5160...   Quench with oil and draw temper to possum ear blue on the tip about 2 inches..   If you are using it for a hot punch and I assume you are I'll bet the tip will exceed  500 degrees temp ... What hardening is left.. ?   

 

Forge on and make beautiful things

 

Jim

[Rich Hale]

S7  is one of the steels most suited for punching,,,,I like that if deforms very little if used while hot. I have never seen references to it being used for springs,,,On any of the steels you can google the specs and see wot it is used for. I think you just got some bad info pm the steel.identity.

[SoCal Dave]

I agree that spring still is probably 5160.  I have used lots of spring steel and oil quenched them in heated oil without problems.  

[windancer]

WOW!

Thanks to all for the new info. I could have sworn that I read that coil springs were S7- thanks for straightening that out.

 

SOOOOOOOOOOOOO..............

 

Never mind :)

 

Dave

[WayneCoeArtistBlacksmith]

Jim, my theory about hardening hot work tools is that if you use them "as forged" they are actually normalized (as soft as it gets except for annealing.  If it has been hardened then tempered and then used to a temperature above the tempering temperature it is still going to be tougher than a normalized too.  Also the hardening and tempering refines the grain structure.

 

The hardening and tempering is relatively quick and easy and if it improves the tool to any extent it is worth the effort.