How To Harden Steel


Knowing how to harden steel comes in handy on occasion. Even though woodturning can be done with very few tools, I can’t help myself from trying anything different. I occasionally buy machines, but I usually make it myself.

Turners used to know how to toughen and temper steel before commercial equipment were accessible. They either crafted their own equipment off from high-strength steel or purchased them from a nearby blacksmith.

The easiest way for how to harden steel effectively and modify steel is to use current techniques. This necessitates the use of the appropriate steel for task, as well as close monitoring of temperatures, pacing, cooling and heating rate. However, the cruder approaches outlined here will typically produce satisfactory results.


How Do You Harden Steel At Home?

  • Place your steel either on a baking tray or directly in an oven rack.
  • Enable the steel to heat in the oven. The steel gets hot enough through the heating cycle to loosen the metals inside, making it less brittle.
  • If you must use a burn torch, guide the flames point to the region that needs to be hardened.

Tool Steel

Carbon steel is no longer used to make turning instruments, but it is also used for a variety of other applications. It still works as well for turning tools as it did once the ancient spinners made a good living with it.

Steel stockholders sell high carbon steel with a variety of grades, some of which are ideal for water tightening and others for oil hardening.

Carbon steel scrap is abundant. Springs, masonry nails, files, saw blades,  woodworking chisels, cold chisels, crowbars, old screwdrivers, plane irons, and a variety of other items may be used to tighten steel for tool making.

I used the notches of an antique garden fork as well as the rings of old ball events to create this sculpture. Realize that if you’re planning to hold the tool under a lot of tension, you shouldn’t use steel that has or may grow cracks.

The gaps between the tooth of such a file, for example, are weak spots where cracking will begin.

Since some modern manufacturing alloys can not react well to these simple heat therapeutic approaches, old steel is always the best option if you’re using scrap. Touching the metal on a mixer is one way to tell what else you’ve got. It’s obviously carbon steel if there are many bright popping sparks.

For a contrast, use a piece of mild steel, such as a regular nail. It would also produce a large number of sparks, but less bursters. The metal’s previous use provides a clue; if that was exposed to a lot of pressure, it’s most likely high silicon carbide. However, there is a carbon content spectrum – the test hardens a part before making the method to be sure.

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Mild Steel With A Low Carbon Content

Mild steel may be a form of carbon steel from a low carbon content – it’s also defined as “low-carbon steel.” The process of hardening mild steel ranges differ based on the location, mild steel usually has a carbon content of 0.05 percent to 0.25 percent by weight. For hardening mild steel, the crystalline structure of it must change.

Most cutting tools cannot be made with ordinary low-carbon mild steel. That type of steel cannot be hardened, and it will lose its sharpness. For hardening mild steel it must have the correct amount of carbon. A harden mild steel may last longer enough to be used as a one-time job because the harden mild steel is tougher than wood.

It develops a quite thin coating of high carbon content over its layer as a result of this. Then, as long as you don’t plug away the hard skin while polishing it, you could use it for a few light-duty machine tools. Apply a specific substance to the metal before heating it to case-harden it. For brazing or inserting on cutting, you may use harden mild steel as a handle.

Required Apparatus

Steel must first be heated until it can be hardened. You can test the temperature with a magnet to see if it’s hot enough for steel hardening; whenever the magnet no longer attracts it, the steel is prepared.

Simply heat it up to red-hot temperatures, and that is also the temperature required for hot mould.

Heat will be needed in proportion to the size of the item. Hardening steel can be done using a flame on a gas cooker if the item is small.

For steel hardening, you can supply air with a charcoal fire and a blower.

With a powerful blowtorch, you can accomplish a lot in steel hardening. Bigger particles of steel can be energy deficit  as quickly as it is added, never reaching a sufficient temperature.

If you’re using a torch, place a few dried bricks to create a heat-retaining enclosure.

It’s not difficult to redesign a simple forge that burns  propane or solid fuel .

On YouTube, there is a video showing how to make an easy yet powerful propane forge.

I built a forge which burnt anthracite but worked 7/8-inch bars with little difficulty.

Forging In The Heat

By hammering two pieces of metal white hot, you may weld them together. The steel will melt and spoil if it gets any hotter. However, with the equipment mentioned, these temperatures are more difficult to achieve.

You’ll also need an anvil, vise, hammer and strong pliers if you’re doing some hot forging. A hacksaw, file,angle grinder, table grinder, and drill are all tools that may be needed. You’ll need bigger equipment and a forge to deal with thick steel.


Any waste carbon steel is also too difficult to develop by slicing or filing. To get it smoother and more workable, you’ll ought to anneal it.

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The first move is to heat the metal up to red-hot temperatures. You can solder it until it’s hot. If you try to work the metal after it loses the red heat, it will break.

It’s crucial to hit when the steel is still hot. After some welding, reheat the steel and afterwards denature it by slowly cooling it. The shorter it chills, the better – in the past the steel was buried in hot coals to cool.

The annealed metal should be flexible enough as to file after cooling. Test that all pieces are gentle, then perform any additional operations that are needed. The tool should be formed, which includes rough grinding the tip.

Firming The Steel

To toughen steel, reheat the component to be strengthened until it is reddish hot second time, ‘soaking’ this one in the sun if necessary, and then extinguish it. Steel hardens due to the quick transition from burning hot to cool. You may use a variety of liquids to quench your thirst, however a jug of water will normally suffice. Immediately plunge the reddish metal into the water and turn it around to chill it as soon as possible.

If quenching causes the steel to warp or crack, consider using oils rather than water, or try a new steel. If you’re using gasoline, you’ll need to take extra care to avoid a burn. Instead of a plastic bucket, use a metal tub. Since the hot steel can warm and ignite the gasoline, keep a metal cover nearby to put out the flames.

What Oil Will Harden Steel? 

Mineral Oil is a third conventional tempering product that is ideal for high-speed metals and oil hardened alloys, as well as any metal that can achieve the requisite hardness.

Hardening steel all sections of a device to the very same extent isn’t always sufficient. If it would be exposed to pressure being used, the majority of it can be left soft for high toughness, with only the chopping tip strengthened.

The metal should have been glass-hard following quenching, and a file should glide off this without slicing it. Don’t push the file too hard; the harding steel steel will blunt it quickly.HOW TO HARDEN STEEL

What is the best oil for quenching steel?

  • For blacksmithing, there seem to be a variety of food-grade tempering oil choices.
  •  Avocado oil, peanut and vegetable oil are only a couple of small choices.
  •  Palm kernel, olive and canola oil are some of the most widely utilized vegetable oils.
  • Vegetable oil seems to be a low-cost, renewable source of energy.


To make hardened steel,the temper steel(temper metal) would be fragile. If you use temper metal in this condition to make hardened steel, the edge will crack or break. Before using the temper metal for most applications, you’ll need to reheat it once more to temper it. Brittleness is removed by tempering to make hardened steel. It will make the metal stronger, but it also makes it softer.

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The steel will become lighter and much less brittle as the temperature rises while tempering. Each device has its own perfect combination of toughness and durability.

Wash the metal with abrasives before tempering. For this point, we want to have the steel to be bright and cheery. Heat the tool carefully over a fresh flame, not in it. As the shiny surface layer heats up, keep an eye on it. Allow the heat to begin away from the fence and creep closer, striving for a consistent temperature across the entire surface.

How do you harden steel for knives?

To harden steel for knives, the knives steel must be heated within 1050-1090 degree celsius range and quickly quenching it. To harden steel for knives is easy process but also brittle.

Keep An Eye On How The Color Changes.

The bright metal can change color as it becomes hotter. It can change from silvery towards light yellow, blue from brown, and eventually grey. You must capture the exact moment when the desired color hits the edge.

A yellowish color at the cutting tool’s edge is usually adequate for sawing wood, but various tools can need different colors. The steel will be rugged and solid, but not strong enough to hold a cutting edge if it is painted blue.

Can Any Steel Be Hardened?

Hardness and quenching can only be done on steel with a high carbon content. Temper steel is often associated with the word “hardening.”

Allowing It To Get Too Hot Is Not A Good Idea.

You’ll really have to restart the hardening steel stage when you let the steel become too hot. The grinding, tightening, and quenching can all be done again without harming the metal.

However, too much time at a higher temperature will cause the carbon to be burned out of the external surface.

Satiate the tool once whenever the color is perfect. After that, it’s time for a final cleaning and polishing before it’s brought for use.

When you need a larger piece equally tempered, for example, more precise tempering is needed.

This can be done by warming the item in a furnace at a certain temperature or by frying it in oil. These techniques would necessitate the use of a thermometer.

They allow for proper soaking temperatures, which can give better results.


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