Polymer Quench Hardening

ThermTech is proud to offer polymer hardening of steel castings when a quench faster than standard oil quenching is required.  Polymer quench hardening is typically employed on castings made from low to medium alloy steel grades and sometimes for higher alloy steels with heavy sections.


All polymer quench hardening processes are ran out of batch-type furnaces for optimum process and lot control.  Our largest furnace capable of performing the process has internal working dimensions of 88”W x 129”L x 42”H.  All ThermTech furnaces are certified to AMS 2750, standards, ensuring optimal temperature uniformity during the hardening process.


The process of polymer hardening for steel castings begins by fully austenitizing the steel in the temperature range of 1500°F – 1650°F depending on the steel grade.  It is held at this temperature for a time commensurate with the part cross-section.  This step can be done using a carbon-controlled protective atmosphere to limit decarb and prevent formation of surface oxidation during the austenitizing cycle if required.

The load is then quenched in ThermTech’s polymer quench tank with vigorous agitation to produce a fully hardened martensitic microstructure in proportion with the steel grade and section thickness.  After the quench, the parts are tempered down to a specified hardness range to optimize properties for the parts’ specific application.  The concentration of our polymer quench solution is carefully controlled to ensure uniform quenches from batch to batch, and also to maximize quench rates while limiting the risks of quench-cracking.   Although Polymer quenches are not as severe as water, the properties of polymer solution have enhanced surface wetting properties which results in more uniform heat extraction.

The careful controls we use for our polymer quench processes make us the industry leader in this heat-treat discipline.  We are able to polymer quench parts to achieve mechanical and charpy impact properties other heat-treaters can’t.


In cases where parts are especially distortion sensitive but still require the superior depth of hardness provided by polymer quenching, ThermTech will tailor the process in order to minimize or eliminate distortion problems while still achieving the required material properties. In cases where distortion is a primary concern, please consider our other quench methods, including oil quench hardening and marquenching.

ThermTech offers polymer hardening processes for castings made from a wide variety of steel grades. Some of the most common polymer quenching processes offered are:

  • Polymer Quenching 4140 Steel

  • Polymer Quenching 1045 Steel

  • Polymer Quenching 4130 Steel

Please be aware that lower final hardness ranges that require tempering temperatures above 900°F may 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 also proud to offer vacuum hardening of castings using either gas or oil quenching hardening.

Contact a sales representative today to learn more about the potential benefits of our polymer quench process!