Normalized Heat Treatment
ThermTech is proud to offer normalizing heat treatments for castings. The process can be employed on cast products to homogenize grain structure, improve machinability and response to subsequent heat treating processes.
All of our normalizing processes are run out of batch-type furnaces for optimum process and lot control. Our largest furnace capable of performing normalizing heat treatments has internal working dimensions of 86”W x 182”L x 51”H. All of ThermTech’s furnaces are certified to AMS 2750, ensuring optimal temperature uniformity during the hardening process.
Non-uniforming cooling after casting can result in non-uniform micro-structures which can result in difficult machinability and non-uniform properties within the casting.
The normalizing process is commonly applied to carbon and alloy steel castings in order to refine grain structure and produce a more uniform distribution of carbon content throughout the material after the casting process. Normalizing can also help alleviate a condition known as “segragation” in which alloying elements segregate during either casting or hot rolling.
During normalizing, castings are typically heated to a temperature slightly above the austenitizing temperature – usually 1600°F – 1750°F to promote atomic mobility that enhances homogenization of the steel. The castings are then held at the normalizing temperature for several hours and then usually cooled in still air. The cooling rate can be altered depending on the final hardness needed.
The final result is a casting that will machine more easily and have more uniform micro-structure. Normalized castings respond to heat-treating better and have more uniform mechanical properties.
Of special interest is ThermTech’s capability to normalize ductile iron castings. Ductile Iron Castings (or DCI castings) often need special cooling rates from above the critical temperature in order to achieve conformance with the mechanical property requirements of a particular grade (100-70-03 is the most common). ThermTech’s staff includes two metallurgists who would be happy to provide advice and input into alloying and processing considerations for your part. Our customers have found that our expertise in this field enables them to meet even the most difficult requirements for DCI parts.
ThermTech offers normalizing for castings of any steel grade, but the following are the most common:
- Normalizing 4140 Steel
- Normalizing 4340 Steel
- Normalizing 8620 Steel
- Normalizing 4130 Steel
- Normalizing of Ductile Iron Castings (DCI) to the 100-70-03 grade
- Normalizing of Ductile Iron Castings to the 80-55-06 grade
If a clean finish is required after normalizing, ThermTech offers several different blasting services to remove any oxide present.
Contact a sales representative today to discuss how our normalizing services can benefit your cast products!