When should you temper a knife?

In its hard and brittle state, the quenched blade will shatter like glass if dropped, it must be tempered before it is put to use. Tempering involves heating the blade to a non-critical temperature (350 – 450 F) to slightly soften the steel (I used a kitchen oven).

How long can you wait to temper a knife?

For the blade to harden, it needs to cool below 900℉. Wait about 10 to 15 seconds before pulling the blade out and checking it for warping. If it looks good, take a file and scrape its corner across the steel.

How soon after quenching should you temper?

Generally, about 15 minutes after your quench, the blade should be cool enough to temper. If you can hold it with bare hands...you're probably good to go.

When should tempering be done?

Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air.

Can you over temper a knife?

While you can definitely over-temper a blade, that will leave it too soft rather than too brittle; you can also over-harden (or, rather, under-temper) it, which will leave it very hard and very brittle.

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Does tempering reduce hardness?

Tempering Applications

Tempering is commonly performed after hardening to reduce excess hardness, since untampered steel is very hard yet too brittle for most industrial applications. Tempering can change ductility, hardness, strength, structural stability and toughness.

Do you need to temper steel after hardening?

The short, simple answer is yes. It is mandatory to temper the steel after it has been hardened. This is simply because a new phase has been created, which is martensite. Remember that it is necessary to progress into the austenite phase before martensite can be created.

What is the purpose of tempering?

tempering, in metallurgy, process of improving the characteristics of a metal, especially steel, by heating it to a high temperature, though below the melting point, then cooling it, usually in air. The process has the effect of toughening by lessening brittleness and reducing internal stresses.

What's the difference between temper and hardness?

The maximum hardness of a steel grade, which is obtained by hardening, gives the material a low toughness. Tempering reduces the hardness in the material and increases the toughness. Through tempering you can adapt materials properties (hardness/toughness ratio) to a specified application.

Do you have to temper a blade after quenching?

After the blade has been quenched, its hardness is still not suitable for usage. In its hard and brittle state, the quenched blade will shatter like glass if dropped, it must be tempered before it is put to use.

How long should steel be tempered?

To reduce the brittleness, the material is tempered, usually by heating it to 175–350°C (347–662°F) for 2 hours, which results in a hardness of 53–63 HRC and a good balance between sharpness retention, grindability and toughness.

What do blacksmiths quench their blades in?

Blacksmiths generally use water, oil, or compressed air to quench. These substances vary in environmental impact, cost, and effects on the metal, but the best quenching medium is usually water or quenching oil.

How can you tell if steel is hardened?

To examine a piece of steel, obtain a hand file and file an edge of the selected metal. If the piece of steel has not undergone the hardening process, the metal file should easily 'bite' into the sample. If the metal has been hardened, the file fails to cut into the sample and glances off with little visible effect.

What are the disadvantages of tempering?

The disadvantage of this tempering method is that cooling in hot environments can't provide a high cooling rate at 400-600 °C temperature range. In this regard, stepwise steel tempering method can be used for carbon steel products with small cross-section (diameter up to 10 mm, for example, drills).

What are the four basic steps of tempering?

Does tempering steel make it brittle?

After the quenching process, steel becomes hard and brittle. In high-stress applications, the material can easily crack and shatter into pieces - very similar to what happens to glass when it drops. These are undesirable effects that can compromise steel in most applications.

Is tempering necessary?

The tempering process is an essential stage in heat treatment, especially in very fast cooling, as it brings back ductility. Before we can start the quenching process we need to heat the steel to a high heat.

Is quenching the same as tempering?

The key difference between quenching and tempering is that the quenching is rapid cooling of a workpiece, whereas tempering is heat-treating a workpiece. Quenching and tempering are important processes that are used to strengthen and harden materials like steel and other iron-based alloys.

What temperature would steel be tempered at?

Purpose of tempering

During the tempering process the steel is heated to a temperature between 125 °C (255°F) and 700 °C (1,292 °F). At these temperatures the martensite decomposes to form iron carbide particles. The higher the temperature, the faster the decomposition for any given period of time.

What happens if you dont temper steel?

it can crack all by its self. it will be very very brittle so much so that the edge might chip when sharpening. you dont lose much with a temper but gane tons. also you might not get the edge you think because the very tip of the edge will be very unstable and hard to sharpen.

What happens if you don't heat treat steel?

Watch For Brittleness

If you don't temper your metal properly, you'll expose your metal products to potential brittleness. Brittleness occurs when metal is tempered for too short of a time.

What happens if you don't quench steel?

A misstep in any part of the process could lead to unsuitable steel.

Does time affect tempering?

There is a significant effect of tempering time on the Charpy impact values of the steel, Fig. 5(b). The impact toughness of the steel substantially decreases with increase in tempering time.