Chapter 3: Hardenability

The crux of this chapter is to develop a method to quantitatively define hardenability. The chapter includes the empirical methods to estimate the hardenability knowing the chemical composition, describes prior austenite grain size, and examines their utility. It then reviews the Jominy end-quench test and explains its relation to hardenability. The chapter outlines the concepts of the critical diameter and the ideal critical diameter, leading to establishing a quantitative measure of hardenability. Next, it examines methods that have been developed which allow estimation of the ideal critical diameter from the chemical composition and the austenite grain size. The chapter reviews the methods which allow calculation of the Jominy curve from a value of the ideal critical diameter. Additionally, it describes the selection and application of H-band steels. Finally, the chapter describes the effect of boron on the hardenability of steels.