What is oil hardening steel ?

Oil hardening steel refers to steel that must be quenched by oil. It’s ideal for achieving the required strength and hardness properties on many alloys with less risk of cracking than water or polymer quench processes.

Usually, when some needs oil hardening steel, he probably means AISI O1 cold work steel. O1 Tool Steel is a very good cold work steel and also makes very good knives and forks. It can be hardened to about 57-61 HRC. And you can check full data for AISI O1 tool steel here.

Process to Oil Quench Steel

We start by fully austenitizing the steel in the temperature range of 1500°F – 1650°F, depending on the steel grade. It’s held at this temperature for a time proportionate with the part cross-section.

The initial austenitizing process is typically carried out under a protective carbon-controlled atmosphere. This atmosphere prevents excessive scale formation on the forged surface.

Once soaked at the austenitizing temperature for the appropriate amount of time, the parts are quenched in agitated oil. This produces a fully hardened martensitic microstructure, the depth of which is dependent on the alloy grade and section thickness.

At this point, the parts are tempered down to the specified hardness range for improved toughness.

In cases where parts are especially distortion sensitive or crack-prone, we will custom-tailor an oil quench process to minimize or eliminate these problems completely while still achieving the required material properties. For extreme distortion tolerances or unique property requirements, take a look at our marquench hardening or austempering services.