Oil Quench Hardening

Oil quench hardening is perhaps the most common method for hardening machined components made from alloy steels.  It’s ideal for achieving the required strength and hardness properties on many alloys while keeping distortion to lower levels than water or polymer hardening.


ThermTech runs all oil hardening processes in batch-type internal quench atmosphere furnaces, which are ideal for process and lot control.  All furnaces are certified to meet the temperature uniformity and accuracy requirements of AMS 2750, and our largest furnace capable of performing oil quench hardening has internal working dimensions of 36”W x 72”L x 42”H and can handle weights of up to 7000 pounds


The process of oil quench hardening for machined parts and stampings is performed by first fully austenitizing the steel in the temperature range of 1500°F – 1650°F depending on the steel grade.

The entire austenitizing process is carried out under a protective carbon-controlled atmosphere that protects the surface quality of the parts under high temperature.  Once soaked at the austenitizing temperature for the appropriate amount of time, the load is quenched in agitated oil to produce a fully hardened martensitic microstructure.  The parts are then tempered to the specified hardness range.

In cases where parts are especially distortion sensitive, ThermTech 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, take a look at our marquench hardening or austempering services.


Please be aware that lower final hardness ranges that require tempering above 900°F will result in temper oxide formation on most steel grades. ThermTech offers a variety of blasting services for machined parts to remove any oxide formation and improve the surface finish. For bright finish requirements for some components, ThermTech is also proud to offer vacuum hardening of machined parts with either gas or oil quenching.

ThermTech offers oil hardening processes of machined parts and stampings for many low-alloy steel grades. Some of the most common materials we offer this process for include:

  • Oil hardening 4140 steel

  • Oil hardening 1045 steel

  • Oil hardening 4340 steel

  • Oil hardening 52100 steel

  • Oil hardening O-1 steel

For heavier cross section parts or for components made from lower alloy grades, we recommend our polymer quench process or our water quench hardening process.  Additionally, ThermTech runs carburizing and carbonitriding processes for lower carbon steels such as 8620 and 1018.

For large volumes of parts and/or to learn more about how our oil hardening process can benefit your products please contact our sales staff for a formal quote today!