How long should I temper my knife?

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.

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.

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.

Can you temper steel too much?

At 600 °C (1,112 °F), the steel may experience another stage of embrittlement, called "temper embrittlement" (TE), which occurs if the steel is held within the temperature range of temper embrittlement for too long.

Can you quench a knife twice?

1) You can quench a blade many times if you are referring to the full HT. Each time erases the hardness and hamon developed in the last quench. The grain gets finer each time,so there is some benefit to a triple quench. The pattern and hardness are the result of the final quench and the subsequent tempering.

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How long should you quench a blade?

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.

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 have to harden knife blanks?

Most everywhere will give you a blank that is already annealed. This means that it is heated up beyond it's critical temperature and cooled slowly so it is in a relaxed state. This makes it soft enough to be drilled, cut, filed, ground, etc. So this is what you'll shape into your blade.

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.

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.

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.

How hot should steel be for forging?

a. Hot forging of steel: The forging temperatures are above the recrystallization temperature, and are typically between 950°C–1250°C. Usually, one experiences good formability (i.e., filling of die-cavity in the context of forging), low forming forces, and an almost uniform tensile strength of the work-piece.

What oil do you quench a blade in?

There are many food-grade quenching oil options available to use for blacksmithing. Among these options are vegetable, peanut, and avocado oil. Some commonly used vegetable oils are canola, olive, and palm kernel oil.

Can you quench in water?

Water is one of the most efficient quenching media where maximum hardness is desired, but there is a small chance that it may cause distortion and tiny cracking.

At what temperature does steel turn purple?

Changes in Color and Appearance

At 520 degrees Fahrenheit, steel turns purple. At 575 degrees Fahrenheit, steel turns blue. At 800 degrees Fahrenheit, steel turns grey. Above 800 degrees Fahrenheit, steel produces incandescent colors.

At what temperature does steel turn red?

Description. Iron or steel, when heated to above 900 °F (460 °C), glows with a red color.

What temperature should you forge at?

While typical hot forging temperatures are between 2150°F and 2375°F – well below the melting temperature of more than 2500°F – deformation (adiabatic) heating results in local heating.

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 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.

Can you reuse quenching oil?

Usually, the post-quench washer is used to recover the quench oil for reuse. This washer must only be used to clean parts after the quench and must not be contaminated with other coolants or other contaminants. In this process, the oil is recovered from the post-quench wash and segregated to a separate tank.

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.

Why do blades warp when quenched?

When these heated parts are quenched, their internal crystal structure changes again, and that volume change is not necessarily sufficient to offset the change upon heating. This change of volume can cause dimensional distortion.