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Heat treating S7 coil spring

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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 :)



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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



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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.

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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.

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