How to Harden Stainless Steel

eHow may earn compensation through affiliate links in this story.

Things You'll Need

  • Kiln or furnace

  • Tank or barrel

  • Machinist's handbook

  • Tongs

  • Water

Raise the strength and durability of stainless steel items by tempering them. Use this guide to help make your stainless steel tools harder and less susceptible to corrosion and stress.

Step 1

Consult your machinist's handbook to find the "austenitising" temperature for your grade of stainless steel. Heat your kiln to about 1/4 of that temperature.

Step 2

Fill your tank with your choice of quenching agents. Experiment with agents such as transmission fluid, brine or water to prevent the piece from warping during quenching. The agent should be around around 60 to 70F.

Step 3

Support the stainless steel item with your tongs and heat it evenly in the kiln. Gradually raise the heat of the kiln to the austenitising temperature and allow the item to reach a moderately red color.

Step 4

Use tongs or a frame to lower the item into the quenching agent; support it to avoid warping. After the piece has cooled and is no longer malleable, remove any excess water from it.

Step 5

Set the kiln to the tempering temperature. Re-submerge the item into the kiln and heat the piece for the handbook's suggested time, usually about 30 minutes.

Step 6

Re-submerge the steel item into the quenching agent and then turn off the kiln.


Avoid warping during this process by experimenting with different support structures and quenching agents.