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Are Lawnmower Blades Heat Treated? 25 Things You Should Know

Before you can buy a lawnmower in readiness for a mowing season which could be spring or summer, there are important questions whose answers you must seek. For example, are lawnmowers heat treated? And if that is the case, what is the purpose of heat treating mowing blades? Does it improve the quality of steel? Now, let’s go back to the main question:

Are lawn mowers blades heat treated?

Based on extensive research we did that involved testing and comparing different lawn mowing blades, the answer is yes. Lawnmower blades are heat treated, albeit sparingly.

Heat treatment of lawnmower blades is important for:

  • Heat-treated blades are resistant to wear and tear
  • Heat treatment straightens mowing blades
  • Heat-treated blades are resistant to wear and tear.

Why Heat Treatment of Lawnmower Blades?

Why is heat treatment important, and should tempering be part of the process?

 The truth is that heating mowing blades during manufacturing have the benefit of making them hard. On this premise, we are talking about something that transcends durability. Heating lawn mower blades to a certain temperature create an even hardness distribution.

If you have used a mower before and accidentally hit on a stamp or stone, you know that softer blades are not the best or safest bet when looking for a tool that will last its worth. Getting hit by pieces of broken mower blades at high speed is the worst experience you can have when mowing grass in your backyard.

Finding a satisfactory answer would depend on some factors for someone who has always used mowing machines. Take, for example, the type of mower one uses. You can also zero into a model of a mower. Another factor that often plays significance is the metallic characteristics of a mowing blade. However, before concluding on matters of heat treatment, let’s set the record straight on brands of mowing blades.

Given that there are more than a dozen brands of lawnmowers, it means that homesteaders have wide-ranging options from which to choose the best one for the money. Also, think about top competing brands such as John Deere, which will further push one to the edge of making the right purchase decision, especially when comparing top-quality mowers and any other brands.

Blade Material and Best Heat Treatment Method

A necessity to harden mowing blades means heat must be involved. However, given that different metals react to heat differently, manufacturers must exercise caution when treating mowing blades. Think about a situation where overly heated metals become brittle; you realize that brittleness is not something about which to worry unless you are handling high-quality steel with less carbon.

According to experts, carbon steel with large grains does not shatter, especially after heat treatment. Remember that mowing blades feature nickel alloy, which is a different story. However, you should note that each company has a unique process unique to its manufacturing protocol on matters of heat-treating blades. That is not to mention that depending on the country of origin, government policies often influence standards of making blades harder and tougher.

Why Heat Treatment of Mowing Blades?

We may have touched on a few reasons that explain why heat treatment of blades is vital but let’s dig deeper. Well, the heat treatment of lawn mower blades has many benefits. They include:

● Even hardness:

The hardness of lawn mower blades is something a handyman must consider before putting money on good equipment. With mowing blades, hardness is a factor that does signify not only top quality but also a rigorous manufacturing process. So, if you asked any company why they harden these blades, a straightforward answer would be to make them hardy and strong.

But from our end of the bargain, heat treatment of mowing blades ensures an even distribution of strength. It is the only way to ensure they last long and withstand tough working conditions. However, overheating blades of lawnmowers beyond a certain degree of temperature comes with an equal share of disadvantages. We will look at some of them later on in this blog.

● Heat treatment straightens mowing blades:

You don’t want to imagine subjecting your lawnmower to difficult working conditions. For example, rough backward terrain full of pebbles and rocks will likely nick the cutting edge. But with a good mowing blade sharpener, that is not something about which to worry. With heat-treated blades, mowing under these conditions presents little worry, if any.

Such blades remain straight and strong no matter how often one hits the mower on stamps and stones. Most importantly, heat treatment of blades withstands the risk of bending anyhow because the process changes metallic characteristics so that atoms are tightly packed for extra strength and durability.

● Heat-treated blades are resistant to wear and tear:

Another reason for heat-treating blades is to make them resistant to wear and tear. While this is closely related to the first two points, note that mowing conditions vary from one homestead to the other. Here, you should think about how often you ended up buying a softer blade that needed sharpening. Even knives and machetes go through a heat treatment process, and according to experts, it reduces the frequency with which you will sharpen your tool.

Sharpening blades excessively means they are soft and hence get blunt quickly. Heat treatment does away with unwarranted softness, giving your mowing blades a longer life. You could say there is more quality in heat-treated blades than those which do not go through the process.

Heat Treatment: Is tempering a necessary part of the process?

Heat treating mowing blades is not a complicated process. With the right conditions, you can do it at home. However, given that metals exhibit different characteristics when heated due to the arrangement of atoms, the input of a metallurgy expert is vital in the manufacturing of mowing blades. Thus, terms like metal hardening and tempering define processes with which you should be familiar.

So, here is the big question. Should heating mower blades to harden them include tempering? And what does it mean?

First off, hardening blades is the first step in the process of heat treating metals. It often results in a metallic product labeled martensite. The process is temperature-controlled to avoid overheating, making blades very brittle and more prone to shattering. Moreover, tempering may be necessary depending on whether a manufacturer needs to toughen blades further or leave them as martensite. The latter process improves hardness to the bainite state- tougher and less brittle metals.

A notable difference between hardening and tempering is that when you stop heat-treating blades at the former state, they are prone to cracking. However, tempering, which some manufacturers refer to as austempering, makes mower blades more ductile. Such are blades that can withstand tougher mowing conditions. In a nutshell, tempering isn’t always necessary, albeit some manufacturers emphasize their procedures for making blades.

What happens if you overheat mowing blades?

Thus far, it is clear that the heat treatment of mowing blades is purposely to make them strong and resistant to wear/tear. But did you know that overheating metals have disadvantages too? While you could argue that too much of something is harmful, let’s be specific in answering the big question. What happens when you overheat mowing metals? Do they become stronger or less ductile?

According to several sources, overheating does compromise the quality of metals, which in this context are mowing blades. Often, you should preheat to a maximum degree of 400 degrees Celsius. However, that may vary depending on the critical temperature of the metal. To put it simply, overheating mowing blades brings about the following disadvantages:

  • Grain conditioning: When you overheat beyond critical temperature, grains in a metal expand. With such a phenomenon comes the risk of making metals more brittle. You can, however, correct the metallic characteristics of overheated blades through a process of thermal cycling. The latter cools hot metals in oil/water to a specified temperature.
  • Carbon content: Another problem that comes with overheating blades is de-carb. To avoid it, go for metals with high carbon content.
  • Carbon diffusion: Carbon diffusion is another problem with overheating mowing blades.

What are lawn mower blades made from, and why are these metals used?

Conventionally, lawn mower blades were made from iron, but nowadays, in modern technology, stainless steel, mild steel, boron steel, and high carbon steel are used. They must be sturdy to resist the force created when they come in contact with a tree stump, small animals, stones, or roots.

They are designed to be bent or twisted when hitting something harder than the grass so they don’t come off and shatter to let the pieces fly away. In 1830, a British inventor designed a mower blade out of iron. Modern manufacturers prefer steel because it is lightweight, corrosion-resistant, and durable.

Let’s see the difference between metals used in manufacturing lawn mower blades:

● Stainless steel Lawnmower blades:

Stainless steel lawnmower blades are a common type for smaller lawnmowers. Such blades are rust-resistant, corrosion-resistant, and have anti-oxidation properties. This metal works perfectly for robotic mowers, as their blades are relatively small. But it is not a good option for riding lawnmowers, walk-behind lawnmowers, and large-sized manual reel lawnmowers. 

● Mild steel Lawnmower blades:

It is also called low-carbon steel. Some manufacturers utilize this material for the preparation of replacement blades. Though it is not as durable, it is more affordable than other steel types. There is a higher risk of shattering; thus, more replacements and sharpenings can be expected. 

● Boron steel Lawnmower blades:

Boron is mixed with carbon steel to acquire the best and the most durable metal for the most powerful lawn mower blades. There is minimum brittleness and maximum durability and strength to produce the most long-lasting and reliable blades. Only 1% Boron is added to 99% steel to provide minimum brittleness for the best performance. It is costly and less resistant to corrosion.  

● High carbon steel Lawnmower blades:

High carbon steel lawnmower blades are among the most affordable and cost-effective metals used to manufacture lawnmower blades. If there is more than 0.55% of carbon in the steel, it is known as high-carbon steel. It is somewhat brittle, so it is more vulnerable to wear and tear earlier than other steel forms. There is minimum risk of shattering but sharpening and replacements are regularly required. They cannot resist corrosion as well. 

● Iron Lawnmower blades:

Iron is affordable and durable but cannot resist rust, friction, corrosion, and other options. If you live in a region that receives heavy rainfall, and your grass stays wet or damp most of the time, I would not choose iron blades. They will need more regular maintenance and replacement, and that adds up. Iron blades’ sharpening is easier than steel ones, and it is flexible enough to resist being touched by stones and tree stumps instead of shattering, making them a safer option. Sometimes iron is mixed with other elements to make it more lightweight and durable for better-performing mower blades.

Ten reasons your lawnmower engine overheats

Overheating can damage your lawn mower’s engine, so it is necessary to understand why this overheating is happening and what you can do about it.

● Engine overheating reason 1: Overworking the machine on wet or damp grass

Wet grass is heavier than dry grass, forcing the mower to work beyond its capacity. So it would be best if you wait long enough for the lawn to dry so that the machine is not stressed and the engine needs less power. 

● Engine overheating reason 2: The deck surface is covered with grass debris

When lots of grass, dirt and other debris collect underneath the cutting deck, it will make it harder for the blades to spin, thus straining the engine and making it run hotter.

The easiest way to prevent the grass from accumulating underneath the deck is to run the mower at its full throttle. Regularly stop and inspect the lower parts of the mowing deck and clean when needed. 

● Engine overheating reason 3: Bent, blunt, dull, rusted, or lose blades

If the blades lose their balance by being twisted or rounded, they will overwork the engine, thus overheating it. Sharpening them regularly and replacing them when needed will eliminate this risk. 

● Engine overheating reason 4: The height of the cutting deck is set too low

You should adjust the mowing height of the deck according to the engine’s capacity. The height is directly proportional to the power. Only a very powerful lawn mower can cut long grass at lower heights. Many others with a less powerful engine will start to overheat.

The solution is easy. Just cut the grass in several steps. Each time lower the cutting deck height until you have reached the required grass height. 

● Engine overheating reason 5: Covered air vents or filters

Ensure that the air filters are always open, allowing your engine to breathe freely. Check the air filter, and clean or replace it when needed. When the air can enter freely, everything is ok. In general, check the air filter twice a year. 

● Engine overheating reason 6: Misplaced engine guard

It is common for the screws and bolts holding the engine guard in place to become loose and fall out over time. This can result in overheating your machine. Regularly check for loose bold and screws, and tighten them when needed.

● Engine overheating reason 7: Engine oil level is shallow

You cannot leave the lawnmower’s engine unlubricated. When low on oil, it will overheat quickly and damage the engine beyond repair. When the oil is old, it will get dirty and is less efficient. I recommend checking it yearly and replace when needed.

● Engine overheating reason 8: Coolant level is very low

There are two types of lawnmowers; most are air-cooled, and some others with a large engine are cooled with water. This is similar to a car engine. If you own a mower cooled by water, ensure the coolant level is sufficient. Regularly check it, and add when needed.

● Engine overheating reason 9: Wrong engine oil is used

You can not use every oil type in a Lawnmower engine. And the type of oil also differs when working in a cold or hot environment. Check the user manual for what your machine needs.

● Engine overheating reason 10: Broken or clogged engine fins

If your lawnmower has an air-cooled engine, it will have cooling fins. If these are damaged or blocked, the air cannot cool the engine properly, resulting in overheating. 

Final Thoughts

Having read and understood everything it takes to have stronger and sturdier lawn mowing blades, you may want to ask one final question. How do you measure the hardness of steel? The answer is that if a blade does not have a Rockwell hardness label, you may have to check a few videos online that will help you test this critical aspect of usability manually. Most importantly, you should note that, depending on the hardness level, sharpening lawn mower blades would be easy or difficult.

Tougher blades may require more than a file for sharpening. A grinder, therefore, becomes a necessary add-on to your homesteading tools inventory. Should you find harder and tougher blades difficult to maintain, there are service providers that can help you do the right thing. Lest we forget. A mowing blade with a Rockwell hardness of 40 and below is way too soft to withstand tough grass and mowing terrain. You will have to adopt a higher frequency of sharpening, but the blades will not last long.

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  1. Brittany Rodriguez says:

    Are there any environmental impacts to the heat treatment process?

    • Allard Vdhooft says:

      Yes, there are environmental impacts to the heat treatment process, including energy consumption and potential emissions. It’s important to consider these factors when making decisions about the heat treatment of lawnmower blades.

  2. Wilma Henderson says:

    What are the different types of metals used in manufacturing lawn mower blades?

    • Allard Vdhooft says:

      Lawn mower blades are typically made from stainless steel, mild steel, boron steel, and high carbon steel. These metals ensure durability and resistance to wear/tear. Hope this helps!

  3. Jennie Burton says:

    What are the best practices for preventing lawnmower engine overheating?

    • Allard Vdhooft says:

      Lawnmower engine overheating can be prevented by avoiding overworking on wet grass, regularly cleaning the deck, sharpening blades, adjusting cutting deck height, checking air filters, ensuring proper oil levels, and maintaining engine fins.

  4. Krin Patterson says:

    Do different brands of lawnmowers have different heat treatment processes?

    • Allard Vdhooft says:

      Yes, different lawnmower brands may have unique heat treatment processes for their blades, contributing to varying levels of quality and durability. It’s important to consider this when choosing a lawnmower.

  5. Yolanda Chavez says:

    Do all lawnmower engines overheat or is it specific to certain models?

    • Allard Vdhooft says:

      Not all lawnmower engines overheat, but certain factors like wet grass, dull blades, or low oil levels can cause overheating. Regular maintenance is key.

  6. Deanna Perkins says:

    How can a homeowner determine if their lawn mower blades need heat treatment?

    • Allard Vdhooft says:

      Yes, you can determine if your lawn mower blades need heat treatment by considering the type of metal they are made from and the conditions in which you typically mow.

  7. Brandie Patterson says:

    Are there any safety concerns related to overheating lawnmower engines?

    • Allard Vdhooft says:

      Yes, overheating lawnmower engines can pose safety concerns such as engine damage and potential fire hazards. Regular maintenance and proper usage are key to preventing overheating.

  8. Kenzi Robinson says:

    Are there any environmental impacts to the heat treatment process?

    • Allard Vdhooft says:

      Yes, there are environmental impacts to the heat treatment process, as it involves the use of heat that can contribute to energy consumption and emissions.

  9. Nicole Reed says:

    How does overheating affect the quality of metal in lawnmower blades?

    • Allard Vdhooft says:

      Overheating mowing blades can negatively affect the quality of steel by making them more brittle and prone to shattering. It is important to avoid overheating to ensure durability and longevity.

  10. Arlene Andrews says:

    Why is heat treatment important for lawnmower blades?

    • Allard Vdhooft says:

      Heat treatment of lawnmower blades is crucial as it increases hardness, resistance to wear, and straightens blades. It ensures durability and safety when mowing various terrains.

  11. Julian Prescott says:

    How important is the hardness of steel in lawnmower blades?

    • Allard Vdhooft says:

      Yes, the hardness of steel in lawnmower blades is important as it ensures durability and resistance to wear and tear. Heat treatment strengthens blades, making them more reliable for tough mowing conditions.