Oil Quenching

Quenching Oil for Hardening Machined Parts & Stampings

Quenching oil is perhaps the most common method for hardening machined components made from alloy steels.

It’s ideal for achieving the required strength & hardness properties on many alloys, while keeping distortion to lower levels than water or polymer hardening.


ThermTech runs all oil quenching processes in batch-type internal quench atmosphere furnaces, which are ideal for process and lot control.

All furnaces are certified to meet the accuracy & temperature uniformity requirements of AMS 2750.

Our largest oil quenching furnace has internal working dimensions of 36”W x 72”L x 42”H and can handle weight of up to 7,000 pounds!

ThermTech offers oil quenching for many low-alloy steel grades, including:

  • 4140 steel

  • 1045 steel

  • 4340 steel

  • 52100 steel

  • O-1 steel


The oil quenching process 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 customize an oil quench process to minimize or eliminate these problems 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, ThermTech is offers vacuum hardening with either gas or oil quenching.

For heavier cross section parts or for components made from lower alloy grades, we recommend our polymer quench processor or our water quench hardening process.

Additionally, ThermTech runs carburizing and carbonitriding processes for lower carbon steels such as 8620 and 1018.

Contact ThermTech today to find out how our oil quenching process can benefit your machined parts or stampings!