History And Advances In Tempering Parameter Development

The results of the stress relieving and tempering processes of steel are dependent on the process temperature and time which are correlated using Holloman-Jaffe equation or Larsen-Miller equation. These equations yield a value known as the tempering parameter, which is a measure of the thermal effect of the process. Processes that exhibit the same tempering parameter exhibit the same effect. In this paper an overview of the development of the tempering parameter, including its origin, use and limitations will be provided. In addition, recent work describing the development of more precise numerical relationships to describe the tempering process will be provided.