How To Heat Treat 5160 Spring Steel?

Let’s start with How To Heat Treat 5160 Spring Steel? 5160 is low-alloy steel that is recognized for its toughness. Many forging bladesmiths have utilized it because of its good qualities and wide availability, notably in the shape of leaf springs.

However, data are scarce on using heat treatment to maximize the steel’s qualities. So, with the help of my father, Devin Thomas, we conducted a brief investigation into the hardness of 5160.

Heat Treat 5160 Spring Steel

How To Heat Treat 5160 Spring Steel?

  • Knife producers like simple carbon steels because they are easy to heat treat. You can do it with simple tools and achieve an excellent result because you have a larger window for success. The procedure outlined above is a tried and true method of hardening certain materials. Do it this way, rather than combining it with something you heard or read, to be specific.
  • 1084, 1075, and 15N20 are examples of simple carbon steels (and 5160, which is often what leaf spring is made from.) There’s a case for using recognized steel rather than a random old piece that might or might not be the grade of steel you believe it is or might or might not contain micro-cracks or other flaws that aren’t obvious on the surface. If you’re going to make something out of an old file or a “mystery steel,” start with this formula, assuming it’s simple carbon steel. If that fails, the steel is either unhardenable or not oil-quenched.
  • You can use a blow torch, a ground fire with a hair dryer, or a gas forge/furnace to heat the steel. Bring the entire blade to the same temperature, as shown by the fact that it is the same color throughout. The tang is unimportant, but the real edge, including the part that goes into the handle, should be at the same temperature.
  • You shouldn’t use the color of the steel as a thermometer to determine when it’s hot enough. Each time you harden blades, you’ll need experience and a constant light environment. From time to time, different lights can easily change the visible color.
  • Getting a magnet from an old speaker, removing the blade from the heat source, and touching the edge to the magnet is much easier. When plain carbon steels, such as 1084/1075, reach “critical temperature,” they lose their magnetic properties. *Anyone who claims this about heat treating stainless steel is well-intentioned but incorrect*.

Simple carbon steels are simple to heat treat. However, the Quench is where you have very little room for error:

When the blade is non-magnetic, take notice of the color because that is what you want. With the blade, quickly bring it to the same temperature as the oil, if not slightly higher. Because the blade loses temperature soon in the air, there isn’t much time between the heat source and the oil.

Pre-heat the oil to 30-40 degrees Celsius by heating a piece of steel in the oil and stirring it around. It’s easy to overdo this, so stir it up and test it with your finger. It’s simple to heat the oil again, but it takes a long time to cool down.

Based on the carbon content, steels are classified as “air cooling,” “oil cooling,” or “water cooling.” The faster (and more aggressive) the Quench, the lower the carbon.

Because simple carbon steels are “oil quenched,” don’t use water; it’s too aggressive and could shatter the blade.

Heat makes the oil more fluid and thin, allowing it to reach closer to the blade and cool faster. Unlike thicker, slower-running cold crude, which could cause a steam envelope around the edge (not cooling it as quick)

Tips For Heat Treat 5160 Spring Steel

  • The blade is delicate when it emerges from the Quench. It should be handled with caution. Release the oil with a damp cloth and sand with fine sandpaper. Sand the flats quickly until you get some bright spots, allowing you to see the Temper colors later. If you can avoid it, do not straighten any bends, drop it, or wait until tomorrow.
  • Place the blade in the oven at 200 degrees Celsius; it’s good to pre-heat the oven. Let it cool for two hours before inspecting the temper colors you obtained. Generally, anything from light straw to dark bronze is acceptable.
  • As the steel in the stove heats, oxide forms on the surface, causing the colors to change. Because these colors are thin layers that build up over time, changing the color, some incredibly bright people have tested this repeatedly, demonstrating that there are apparent “rules” for what color appears based on temperature. We regard your blade’s golden/brassy colors to be “proof” of effective tempering exceptional work. Make a note of what temperature you set your stove to and what colors you got so you can adjust next time if important (Taking notes is as important as “Don’t remove the angle grinder’s guard” and “wear a dust mask,” even if those are more “how and where to live to retirement” type of instructions).


That’s everything about How To Heat Treat 5160 Spring Steel? Suppose you want more answers to your questions. Visit again to get updated. With an austenitizing temperature of 1500-1525°F and a tempering temperature of 375-400°F, 5160 possesses excellent toughness. When heat treated with a cryo stage, this results in 58.5-59.5 Rc and highly high toughness.

Frequently Asked Questions

Is it possible to heat treat spring steel?

Cold working, especially cold drawing, boosts it even more. The most effective elastic limit and the best fatigue properties are produced by heat-treating spring steel. The condition of the surface should be sound and smooth. Steel springs’ fatigue strength is significantly harmed by corrosion and decarburization.

When tempering spring steel, what temperature do you use?

Spring steel tempering (300-500°C): utilized for spring steels and similar purposes. The hardness criterion is usually approximately 45 HRC. Quenched and tempered steels, hot working tool steels, and high-speed steel are all made at high temperatures (500°C or above).

Is it possible to water Quench 5160 steel?

Water-quenching is used by both Kris Cutlery and Himalayan Imports to harden the edges of 5160 blades. In the case of HI, we have photos of them performing it by pouring water directly onto the heated blade from a teakettle. This may be sub-optimal when you progress to longer, thinner blades.

Is it possible to harden spring steel?

The high yield strength of spring steel is accomplished through one of two production processes: (1) heat treatment or (2) work hardening. Heat treatment is used to harden steel by heating it and then quenching it to cool it down to room temperature quickly.

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