Heat Treat and Tempering 52100 for Springs


Well-Known Member
I've got some of Aldo's 3/32" 52100 that I plan on using for slipjoints.

My question is, what temp/color do you temper the springs?

I'm assuming your heat treat the springs the same as your would the blades and then just temper them back. I haven't tried yet, but I was thinking dark purple/blue. But I ask because I want to make sure first! :)


Well-Known Member
Blue is what i shoot for with carbon steel.
I make sure i temper the spring together with the blade....well and throughly, multiple cycles.
After that i sand out the golden straw oxydes, clean with acetone or alchool, take the torch and "paint" the flexing portion of the spring until it turns blue.
This way i have similar hardness in the contact areas (to avoid galling), while i have more toughness in the flexing portion.

Overdoing the tempering will only hinder the springness...the stiffness is only ruled by the spring height in the flex area. The blue hue ensures getting rid of just enough brittleness to work properly.

If you have trouble with hypereutectoids, just do the spring with lower carbon steels