Are Lawn Mower Blades Heat Treated?

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You have probably heard of heat treated knives that manufacturers claim improves its quality and durability. But does this apply to lawn mower blades as well? If you are planning to buy a lawn mower, knowing the answer to this question is important. That is what this post is for, to explain the facts about heat treating mower blades.

The vast majority of lawn mower blades are heat treated. This process, which includes tempering and hardening, makes blades more durable and less susceptible to wear and tear.

Heat treating a blade means hardening as much as possible, and then tempering to the ideal hardness level. There might be slight differences in the process but the basic procedures remain the same, whether it is for a kitchen knife or a lawn mower blade.

The Benefits of Heat Treating Mower Blades

There are many advantages to heat treating blades, but the most important are:

  • Increases hardness and durability
  • Makes it less vulnerable to wear and tear
  • Blade is more resistant to bending and cracks
  • Will last longer even with constant use

Lawn mower manufacturers use different ways to apply heat treatment on their blades. While almost all modern mower blades including the MaxPower 3315288 get heat treated, it is not by much. There is a good reason for this because it only takes a bit of the process to make blades stronger.

Once the blade has been heated and tempered, it becomes much harder and durable. More importantly, it is better suited for heavy duty work. Now that you have a general Ida of what blade heat treating is about, we can take a closer look at the benefits.

A Harder Mower Blade

It takes more than just a sharp mower blade to cut grass. You also need the blade to be hard enough to withstand the terrain. It is not just grass the blade will come across, but also rocks, soil, roots, tree branches and all sorts of debris.

An ordinary mower blade will break if it runs into a very sharp rock. At the very least the blade is damaged and unusable. The worst thing is parts of the blade could fly off, which can be dangerous while you are mowing.

Heat treatment hardens the blade so that it can better withstand rough ground materials. So if your lawn has a lot of rocks, wood and other materials, heat treated blades will be beneficial.

Uniform Strength and Durability

Heat treating does more than just harden a blade, it ensures the hardness is even throughout. From one end to the next, you are assured the blade hardness is equal.

Have you ever used a blade where one area chips faster? That is an example of uneven hardness. One part of the blade may be extra hard but the rest is much softer. So if you have the Greenworks 24V Cordless Lawn Mower, the blades must be sharpened uniformly.

This will cause all kinds of problems when mowing. Mower blades with unevenly distributed hardness will wear out quickly. This will also affect performance and the results will appear on your lawn.

By subjecting the blade to heat treatment, you are assured it is one solid piece, hardness wise. This is going to make a difference in terms of performance and reliability.

Blade is Resistant to Bending and Breaking

Another way to put it is that heat treated blades will stay straight even with heavy use. As anyone who has used lawn mowers before will tell you, low quality blades bend or even break when under immense pressure.

Going back to our example, rocks, roots, etc. can pose problems for low quality blades. A sharp rock can cause the blade to bend or crack. This will be a huge inconvenience especially if you do a lot of heavy mowing.

If you have been mowing for a while, you have probably seen blades bend or break. With heat treatment this can be minimized. That is the reason why the major brands all heat treat their blades.

Longer Lifespan

More than anything else, heat treatment makes lawn mower blades last longer. This will literally save you dollars and make mowing more efficient.

Have you ever tried to sharpen a mower blade? It only takes a few minutes even with a hand file, but it can get tedious when you do it over and over. And that is what will happen with a poor quality blade. The material is not hard enough to withstand constant use.

This is where heat treatment comes in. When the blade is subjected to this process, it hardens to the highest possible level without breaking it. Then it is tempered. By the end of it, you have a durable, hard blade that is built to last.

Can You Over Heat Mower Blades?

Lawn mower blades from the top brands have already been subjected to heat treatment. There is no need for you to do anything else. These blades are already sharp too so it is just a matter of using it.

But to answer the question: yes, it is possible to overdo the heat treatment process. Majority set the maximum temperature at 752 F / 400 C, but this can vary depending on the blade and how it was made.

So unless you know what you are doing, do not put your lawn mower blade under heat treatment. It has already gone through that process during manufacturing. If the blade has dulled, you just need to sharpen it. And if there is damaged, the best option is to buy a new one.

So while heat treatment is good, too much of it will cause damage. What kind of damage depends on how much excess heat treatment was applied.

But the most common problems have to do with carbon, specifically carbon diffusion and content. An overheated blade can also suffer from grain expansion. When the grains on metal spread, it can make the blade more brittle. The way to counteract grain expansion is with thermal cycling, whereby the blade is cooled to the necessary temperature.

As you might expect, this is a complex process and should only be done if you know what type of metal the blade is. You also have to know exactly what temperature to use and for how long. If you overheat the blade it will turn brittle.

Image Source: Santeri Vinamaki

Heating, Tempering and Hardening

So far we have established that lawn mower blades are heat treated and tempered. But are they also hardened?

The answer is yes, majority of mower blades are hardened. The reason is when you combine all these three elements, the blade becomes much strong, durable and resistant to damage.

When properly done, heat treated blades are going to last longer. To be more specific, these mower blades have hardened edges and are also heat treated. When you combine these two it provides the blade with more flexibility without compromising its durability.

If you are going to buy a lawn mower for the first time, get one from a reputable brand. This provides assurance that the blade has been heat treated and hardened properly.

A properly heat treated blade will run for a long time. A typical mower blade only requires sharpening once a year with regular use. If you have a well maintained lawn with few debris, these blades will last for years.

If you find the blade is no longer mowing like it used to, that means the edge has dulled. You simply need to sharpen and the blade will be good to go.

At some point though the sharpening will only go so far. In that case it is better to buy new blades than putting it through heat treatment one more time.

If you have the experience and know how, it is possible to heat treat a mower blade, or any blade for that matter. But it requires welding tools and experience. So it is more practical to install new blades on your mower and start using it again.