HM-407 revisedWhat is heat treating?  Simply defined, it is the controlled heating and cooling of steel in order to enhance certain mechanical and physical properties.  We could go into a deep metallurgical explanation, but you would probably fall asleep, or get easily distracted by all the extra research you would do on tempered martensite or retained austenite.   Heat treating is a commonly misunderstood topic, we hope to guide you in understanding some of the basic processes that will hopefully lead you to asking the right questions about the materials you select and the processes you specify in order to build the best tool you can build.

The following is a list of some basic processes that should be considered with any tool steel heat treatment:

  • Stress relief… Why? It reduces dimensional distortion
  • Preheating… Why? Minimizes thermal shock
  • Hardening temperatures and times… Why? Proper temperature and times are critical in producing the desired properties.
  • Quench method… Why? Sets the proper microstructure, can cause cracks if done incorrectly or if certain design characteristics exist.
  • Tempering… Why? When it’s done is critical as much as how it’s done. The goal is to stress relieve the stress introduced at the quench or create a tempered martensitic structure, the more tempered martensite the better the part or tool.
  • Understanding how these processes relate to the standard practices of your local heat treater is key in having a successful relationship with your heat treater. We will discuss how the relationship with your heat treater is critical in achieving the desired part properties in a future blog.


At Hudson, our goal is to “Make Tool Steel Easy”, as we add to the discussion in future posts we hope it will help you gain a better understanding of materials and processing through asking the right questions. Have a question? Call us or send an inquiry through our “Have a Question?” form. We look forward to helping you with any of your tool steel questions.