Are Lawnmower blades heat treated?

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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?

Well, for someone who has always used mowing machines, finding a satisfactory answer would depend on some factors. 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, something that will further push one to the edge of making the right purchase decision, especially when drawing a comparison between top quality mowers and any other brands.

Now, let’s go back to the big 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. That triggers another question. Why heat treatment, 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 result in even distribution of hardness. If you have used a mower before and accidentally it 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 blade at high speed is the worst experience you can have when mowing grass in your backyard.

Lawn 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 heat treating mowing blades. Think about a situation where overly heated metals become brittle, you realize that unless you are handling high quality steel-with less carbon, brittleness is not something about which to worry.

Carbon steel with large grains, according to experts, does not shatter, especially after heat treatment. Remember that mowing blades feature nickel alloy, which is a different story. You should, however, take note that each company has a different 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 not only signify 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 even distribution of strength. It is the only way of ensuring that 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, a rough backward terrain-full of pebbles and rocks will most 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 present 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, take note that mowing conditions vary from one homestead to the other. Here, you should think about how many times you ended up buying a softer blade that needed sharpening every often. Even knives and machetes go through a process of heat treatment, and according to experts, it reduces the frequency with which you will sharpen your tool.

Sharpening blades excessively means they are soft 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 as martensite. The process is temperature-controlled to avoid overheating, something that would make blades very brittle hence more prone to shattering. Moreover, depending on whether a manufacturer needs to further toughen blades or leave them as martensite, tempering may be necessary. The latter process improves hardness to 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 austempering, make 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 it in 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 has disadvantages too? While you could argue that too much of something is harmful, let’s be a bit 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:

  • 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 metallic characteristics of overheated blades through a process of thermal cycling. The latter is cooling hot metals in oil/water to a specified temperature.
  • Another problem that comes with overheating blades is decarb. To avoid it, go for metals with high carbon content.
  • Carbon diffusion is another problem that comes with overheating mowing blades.

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 level of hardness, you 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.