What is Metal Quenching and Its Advantages?

23 August 2016

Heat treatment techniques use a two-step processing methodology. Logically, it begins with the workpiece entering a fiery environment, perhaps a gas-fired furnace. Here, the metal component is subjected to enough thermal energy to modify the metal’s base properties. This elevated temperature is intelligently maintained, but the time comes for the part to be cooled, which is when the metal quenching stage enters the treatment work. Lowered into a bath full of oil or water, the part cools rapidly.

What Does Quenching Do?

Much effort is put into precisely heating a ferrous or non-ferrous component. The thermal treatment normalizes the part, hardens it, and removes work-incurred stress. Naturally, these astutely interred properties should remain intact and unaffected as the part cools. Unfortunately, the cooling stage represents yet another journey into the material modification realm. This is why we use metal quenching, as this accelerated cooling technique is regarded as a way of quickly cooling the hot part while retaining all heat-tailored properties.

Endorsing Change as a Material Modifier

Rapid cooling in water equals a climactic lockdown of the microcrystalline structure within the workpiece, but what if some material variations are desired? Quenching is used to harden metal parts, including steel. In stainless steel, for example, the austenite-induced state is rapidly cooled until it transforms into its martensite form, which is a brittle configuration, one that will require further tempering. Meanwhile, other material properties can be achieved by switching the cooling medium. Water is commonly used in these tanks, but oil and brine water are also employed, as is high-pressure nitrogen quenching.

A Focus on the Advantages

Although it may sound counterintuitive, the controlled cooling of a hot metal part is every bit as important as the furnace stage, for this heat treatment method controls phase changes on the downward arc of the thermal cycle. Hardening is managed in this manner, as is the deadlocking of heated metal states. Of course, the quenching bath must be carefully used, for a substandard cooling station can introduce material cracks and parts deformation. Furthermore, a superior quenching station is a highly adaptable heat treatment asset, with oil and salt baths transforming the metal part into other, more desirable grains. These are the bainite and pearlite forms, the grains that emphasize certain carbon-rich lattices while minimizing others.

A well-supervised metal quenching station universally hardens a component and prepares it for tempering. Further fluid control elements, including oil and brine, enhance mastery over this rapid cooling phase, thus breathing a versatile state-altering mechanism into the process.

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