Why do you preheat quench oil?

I figure preheating the oil does one of two things. It either lowers the shock for the quench, making fractures and bends less likely (hope it's this one, because it didn't happen) or it hardens better because it makes the oil less viscous, meaning it can transfer heat away from the blade better.

How warm should oil be for quenching?

Quenching into oil above 212°F (100°C) has traditionally been referred to as "hot oil" quenching. Oil temperatures in the 195°F - 450°F (90°C - 230°C) range have been used with both ends of the spectrum normally reserved for special applications.

What does quenching hot steel in oil do?

How quenching oil works. Quench oils have two primary functions. First, they harden the component by controlling heat transfer during quenching. Second, they enhance the wetting of the component in order to minimize undesirable conditions that may cause distortions and even cracking.

What is hot quenching?

Definition of hot-quench

: to quench (a metal) in a hot bath (as of molten salt, lead, or oil)

Can you reuse oil after quenching?

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.

How To Pour Quench Oil, PROPERLY

What happens when you quench steel twice?

Double quenching indeed leads to grain refinement and overall microstructural refinement. However, the second austenization temperature must be the same or lower than the first austenization temperature to achieve this.

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.

Why do you temper steel in oil?

Parts made of low-carbon steel and low-hardenability alloys quench better in fast oils. Hot oils are kept at much higher temperatures and are used to ensure that a part's core temperature and surface temperature do not vary too greatly during a quench. This controls distortion and reduces the risk of cracking.

What is the purpose of tempering after quench hardening?

After being quenched, the metal is in a very hard state, but it's brittle. The steel is tempered to reduce some of the hardness and increase ductility. It's heated for a set period of time at a temperature that falls between 400° F and 1,105° F.

How do you make steel harder but not brittle?

To make steel harder, it must be heated to very high temperatures. The final result of exactly how hard the steel becomes depends on the amount of carbon present in the metal. Only steel that is high in carbon can be hardened and tempered.

Does quenching increase toughness?

Abstract. Quenching and Tempering (Q&T) has been utilized for decades to alter steel mechanical properties, particularly strength and toughness. While tempering typically increases toughness, a well-established phenomenon called tempered martensite embrittlement (TME) is known to occur during conventional Q&T.

What is the best oil to quench a blade?

Does quenching make metal brittle?

Quenching results in a metal that is very hard but also brittle. Gently heating a hardened metal and allowing it to cool slowly will produce a metal that is still hard but also less brittle.

Is Parks 50 a fast quench oil?

Parks 50 is considered a fast oil. Many times a quench oil is described in seconds quenching using a Nickel Ball test. The Nickel Ball quench time is 7-9 seconds.

How long does quench oil last?

Oil Recovery

Quenching and martempering oils deteriorate during use, although most premium quenching oils can last more than 10 years when given reasonable use and care.

What temperature should you quench a knife at?

Step 2: Quench

(The block ensures that both sides of the blade are evenly cooled.) Many knifemakers recommend using canola oil heated to around 130℉, saying that water tends to cool the steel too quickly, which can lead to cracking, especially if the blade is on the thin side.

Why do we need to temper?

Tempering is a method used to decrease the hardness, thereby increasing the ductility of the quenched steel, to impart some springiness and malleability to the metal. This allows the metal to bend before breaking.

What is tempering and why is it necessary?

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?

Hardening or quenching is the process of increasing the hardness of a metal. Tempering is the process of heating a substance to a temperature below its critical range, holding and then cooling.

Does tempering increase hardness?

With the increase of tempering temperature, the hardness of the steel decreases and the toughness increases. The secondary hardening occurs when the steel is tempered at 550°C, which leads to an increased hardness of the steel.

Does tempering hardened metal or soften it?

Tempering is used to improve toughness in steel that has been through hardened by heating it to form austenite and then quenching it to form martensite. During the tempering process the steel is heated to a temperature between 125 °C (255°F) and 700 °C (1,292 °F).

Why do you quench in oil instead of water?

Oil has a slower rate of cooling compared to either water or brine, but faster than air, making it an intermediate quench.

Can you harden steel multiple times?

You can repeat simple quenching heat treatment numerous time if sample is austenitized before hand.

What does tempering a blade do?

Tempering involves heating the blade to a non-critical temperature (350 – 450 F) to slightly soften the steel (I used a kitchen oven). A tempered blade will hold a sharp edge and still retain strength and flexibility.

What liquid is used to quench steel?

Water is an effective medium when the goal is to have the steel to reach maximum hardness. However, using water can lead to metal cracking or becoming distorted. If extreme hardness isn't necessary, mineral oil, whale oil, or cottonseed oil may be used in the quenching process instead.