Why Do You Heat Treat A Knife

A lot goes into the process of making knives into the functional tools that they are today.

Whether kitchen knives, pocket knives, swiss army knives, or other kinds of knives, heat treatment of the blade is an important process.

But why is heat treatment important at all?

Heat treating the knife steel makes it hard enough for sufficient durability such that the blade is still flexible to bend under normal usage without breaking. A well heat-treated knife will retain its edge for a longer time, not break under usage and last for many years to come.

What Is the Right Heat Treatment Level for Knives?

It depends.

Not all knives are used for the same purposes.

For example, we have kitchen knives and there are the EDC knives too.

Even under the kitchen knife category, there are the santoku and chef knives, paring knives, tomato knives, cheese knives, and more.

You cannot expect a cheese knife to carry the same hardness as a meat cleaver. That is the same way that the chef or santoku knife is expected to be tougher and longer-lasting than the average serrated bread knife.

Thus, manufacturers will apply different heat treatments to knives based on the intended purpose of the knife.

Can You Make A Knife Without Heat Treating?

Heat treatment is ideal for getting the most desired properties from the knife-making steel, putting out a series of undesired aspects.

In some cases where the setup for the process is not available, though, you can always make a knife without heat treating it.

Note that this is not something I would recommend if you are a manufacturer that wants to be taken seriously.

If, for any reason, you want to do this, find a video that will guide you through one of the processes below:

How to make a knife without heat treating

How Long Does It Take to Heat Treat A Knife?

The heat-treating process can be summarized into three steps:

  • Normalization
  • Quenching and
  • Tempering

Each of these steps occurs at different temperatures.

Likewise, depending on the kind of heat treatment and what results you want to get from the steel, you would need different temperature ranges.

Speaking of temperature ranges, there are different kinds of stainless steel to consider. From VG10 to blue steel, high carbon stainless steel, and more, their thermal conductivities are different. The rate of heat treatment will also be dependent on how well the material conducts heat.

That said, the quality of your setup plays into the time. While industrial gear will get to the desired temperatures faster, you might have some issues with home setups.

What Temperature Is Best for Heat Treating A Knife?

The ideal temperature to heat treat a knife at is a function of the purpose of the knife too.

Knives tempered at high temperatures come out tougher with softer materials while knives tempered at a lower temperature will yield a harder but brittle blade.

Survival, outdoor and camping knives can be tempered within the 175 – 350 degrees Celsius range (as the lower to the upper boundary), depending on the purpose.

Tending towards the higher end, the knife will tackle rough usage without breaking down. When the focus is on the knife keeping a sharp edge for a longer timeframe too, the temperature should be reduced as it tends towards the lower boundary.

How to Heat Treat A Knife at Home

Are you making your knives at home?

Maybe you’ve got a DIY project and would like to heat treat your knife.

No matter which it is, you can heat treat your knives at home too.

I cannot guarantee that you will get the same results as will come from industrial forges, but you’ll get the hang of it anyway.

I have found a really helpful video to help you get through heat treating your knife at home here:

Mistakes to Avoid When Heat Treating Knives

While heat treatment is there to make the knife steel soft for use yet tough at the same time, you could get it wrong too.

Likewise, when buying knives, this heat treatment is one of the reasons why I consider brands when choosing my knives.

Any of the following mistakes could lead to a poorly heat-treated knife:

  • Lack of normalization – This causes different parts of the knife blade to have different grain structures. Thus, the knife blade doesn’t heat up or get treated at the same rate which leads to inconsistencies. Thus, a bad knife is formed.
  • Poor temperature range – When the knife is not heated up enough, the grains are not re-arranged as much as desired. This doesn’t give you the right results on your knife.
  • Poor timing – The knife steel has to be left in for the right amount of time. Not too long or too short a timeframe that the knife doesn’t get properly treated.
  • Insufficient/ improper quenching.
  • Too much or insufficient tempering.

If you’re tempering your knives by yourself, make sure to avoid these mistakes. If you are buying knives instead, look through these buying guides to pick the right knife across various categories.

Final Words

Seeing a finished knife looks like it was just fabricated from a sheet of metal, and that was it.

Even though that is how stamped knives are created, the steel was still most likely treated and tempered so that the knife works best as it is intended.

Likewise, this helps you understand that different knives are best used for what they were intended for lest they break under extra pressure.

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