The 3rd term to be discussed is quenching and the desired outcome from this process.
The quenching operation is extremely important in setting up the proper microstructure of the steel. There are many mediums that can be used to quench steel such as oil, air, salt and steam to name a few.
The purpose of quenching is to transform austenite to martensite, or in simpler words, create a martensitic structure (larger volume) and stop the cooking process. The goal of an optimal quench cycle is to achieve as much transformation as possible to martensite with no or very little austenite (retained austenite) left in the steel.
Note: if the material is still non-magnetic after quenching, the cooling rate was too slow (no transformation has taken place) and your datums have probably shrunk.
The material should be transferred to tempering immediately after tempering and while the steel is between 90f and 120f. Allowing it to fully cool to room temperature could result in the build-up of an excessive amount of quench stresses, which could cause cracking.
At Hudson, our goal is to “Make Tool Steel Easy”. We hope the discussion in future posts will help you gain a better understanding of materials and processing through asking the right questions. Have a question for us? Call us at 800-996-0411 or send an inquiry through our “Have a Question?” form. We look forward to helping you with any of your tool steel questions.