How To Heat Treat 1095 Steel

1095 steel is a high carbon, simple steel which offers a perfect steel for creating knife blades.

Being the highest carbon simple steel available, it must go through the heat treatment process to be properly hardened. However, 1095 is a reliable high carbon steel when heat treated, so it makes the perfect material to use for your knives.

The heat treatment process involves normalizing, quenching and tempering, and results in a specific hardness depending on the temperatures used. Below, we have set out some of the steps in order to get the best results for the heat treatment of your 1095 steel. These instructions are aimed at the process of using a heat treat oven, but the same processes can be used for forging.

Tools required for heat treating

Before you start the heat treating process, you will need to gather together the following tools:

• A quenching vessel (ensure this vessel is made out of steel and is secure so that it can not fall over)

• 1095 carbon steel

• A heat treating oven (you may choose to forge as an alternative)

• Mineral Oil (as an alternative some people use water or brine however, these can leave cracks in the steel)

• Gloves

• Tongs

You should preheat the oil to 120 degrees, this can be done by heating a steel and placing it into the oil and stirring to warm or alternatively you could use an electrical burner (be sure to follow the safety instructions) to heat the vessel. This will ensure that the steel is not shocked when it hits the oil and does not crack.

Normalizing (annealing)

Normalizing or annealing is exactly as it sounds. It resets all of the ingredients within the carbon steel and ensure that any faults in the grain or stresses in the steel caused by previous working of the steel are negated. Proper stress relieving and normalizing are perhaps the only ways to reduce or eliminate warpage and distortion in the heat treatment.

This process should be used on all steels including the 1095, before the quenching process unless previously completed before purchase. If the blades have arrived from the manufacturer having already been through this process, then this can be missed before being heat treated.

The first step is to place the 1095 steel into the forge or heat treating oven. Ensure the temperature reaches between 1500 degrees fahrenheit and 1600 degrees fahrenheit. The blade should be a 'cherry' red colour when removed. Then, allow the steel to cool in still air, this process may need to be repeated to ensure the form is not effected during the following processes.

Quenching

The 1095 steel should be allowed to soak in the oven for a minimum of 30 minutes but dependent on size of the steel, it might require longer to soak. For the 'soak', remove the steel from the oven. It is important to quench immediately by submerging the steel in the mineral oil solution. The steel will need to be quenched in the solution until temperature drops below 250 degrees Fahrenheit.

Once quenched, you should allow the steel to cool. Steels will need to cool to room temperature following the quench. Quenching is an important process to harden the steel, as without quenching, the knife edge would be too brittle to use. If the blade warped during quenching, you have until the 1095 steel has cooled in still air to below 200f, to rectify any problems.

Before tempering, testing the edge of the blade is advisable. This testing can be done by running an iron file along the edge to check the hardness. The hardness can be checked by the impact the file has against the grain.

Tempering

Once heated, the 1095 steel blade can become brittle so it needs to go through the process of tempering to develop the blade's hardness. Return the steel blade to the oven and bring the steel up to tempering temperature (approximately between the range of 400-500 fahrenheit).

Changing the tempering temperature will affect the hardening of the steel. Higher tempering temperatures lowers the resulting hardness, so you will need to think about the toughness you would like your steel to be before warming. A heat treat oven allows precise temperature control which can not be maintained by using a forge, and may therefore affect the toughness. The blade will need to be in the oven on average for 2 hours.

Once the steel has reached the appropriate temperature, allow the steel to cool slowly to room temperature. Some people allow their steels to cool within the oven, whereas others remove them to ensure the temp doesn't affect the toughness of their final knife.

Important information when heat treating 1095 steel

When heat treating 1095 steel, it is important to ensure that safety measures and procedures are followed at all times during the heat treating process as there can be a high risk when working with such a high temperature. Ensure tongs and gloves are used as items can be extremely hot.

Top tips to consider

Using this type of carbon steel for a first heat treat experience may not produce perfection, as these carbon steels require a very specific temperature and can be a bit prone to warpage.

Some people question the need for heating of the oil before the blades are placed in to quench but this is done to prevent a vapour barrier from forming causing a reduction in the heat transfer to the oil. Therefore it is a valuable process to complete before the quench.

To check that you have reached the correct temp when heating the blade, you can use a magnet, as when steel reaches a certain point (around 1425 degrees fahrenheit) it becomes non-magnetic. So, you can use a magnet to gauge if concerned the temperature might be too low. You can also use the color of the steel at these temperatures as a gauge to how much higher the temperature will need to get, and judge it by the coloration of the steel at these temperatures.

Complete your steel normalizing in much the same way each time, so the color of the steel is similar each time. This makes it easier to make like for like changes, with lower discrepancies.

Be careful not to overheat the steel before quenching as this can lead to grain growth and weakening of the blade which would lead to a break or crack along the blade edge.

Rotation of the the steel during the tempering stage is recommended to ensure there would be an even temp across the blade.

Summary

When looking to heat treat your steel, it is important to practice and practice to ensure that you get consistent results.

A heat treat oven provides better control than a forge, as you can maintain temperatures and also better measure the impact of your heat.

At Soul Ceramics, we have a range of heat treat ovens perfectly suited for controlled heating of your steel at low or high heats. Whether you are looking to produce knives for leisure or as a business, we can offer you the advice you need to ensure that you get the right machine for your needs.

Further reading:

• How to make a knife: a step by step guide
• Choosing the best steel for knife making