DIY Projects: How To Temper Steel

by Diane Barnes

Tempering is a method is hardening steel—or any mild metal. The process works by exposing the metal to heat, which realigns the carbon and iron molecules to create a stronger metal. Although professionals usually do tempering, experienced DIY-ers can do it themselves in small batches.

If you want to temper steel—be it a small knife or spring—follow the steps below:

1. Set up Your Workspace

Before you get started, it is important that you set up your workspace. For this project, you will need:

  • Propane torch
  • Leather gloves
  • Pliers
  • Metal bucket
  • Baking Oven
  • Hands-free thermometer
  • Water

Gather all materials and place them in your clean workspace. While you are at it, fill your metal bucket (that is large enough for your metal object) with water. Place the bucket nearby and preheat your oven to 500 degrees Fahrenheit.

While the oven is preheating, clamp the metal object you are tempering with the pliers. Finally, put on your leather gloves.

2. Fire up the Torch

When you are ready, heat up your propane torch and place the metal object in the flame. Leave the object in the flame until it reaches a light red color. Use the thermometer to check the temperature. For most steels, including cold-rolled, the temperature should be at least 1,500 degrees Fahrenheit.

3. Quench

Once the steel reaches 1,500 degrees Fahrenheit, turn off the torch and place the object into the water-filled metal bucket. Leave the object in the water until it stops making a sizzling noise. When it no longer makes noise, take it out of the water. It should now be much cooler.

4. Bake

Immediately after you take the metal out of the water, place it into the preheated oven. Close the door tightly and let the metal bake in the oven for one hour.

5. Cool

After the hour has passed, remove the metal and let it cool to room temperature naturally. Do not put the metal part back in the water to speed the cooling process, as the metal may become brittle and break.

Once the metal piece has cooled, it is ready to be used.

Please note: while small pieces can be tempered at home, it is best if larger projects are left to the professionals.

If you have a big project coming up, contact a professional to obtain a quote. In addition, if you do not feel comfortable working with very hot materials, contact a professional. Tempering metal can be very dangerous if you do not know what you are doing.