CALCULATED HARDENABILITY FOR IMPROVED CONSISTENCY OF PROPERTIES IN HEAT TREATABLE ENGINEERING STEELS

Hardenability is one of the most important parameters controlling the heat treated properties of engineering steels. it affects the consiste ncy of response for microstructure, hardness, strength, toughness, and dimensional change (distortion). This study illustrates that a major benefit of controlling hardenability is improving the consistency of d imensional distortion resulting from heat treatment. To facilitate the supply of steels to hardenability limits, especially restricted harde nability, a new technique was developed for the prediction of Jominy h ardenability from chemical composition. The technique, termed the ''Da tabase Method,'' uses measured Jominy hardenability and chemical compo sition data, contained in a database, to calculate the hardenability f or a query composition. Using up to ten known steels, selected from th e database with compositions closely matching that of the query steel, a small adjustment is made to the measured hardenability of each know n steel allowing for the small difference in composition between the q uery and chosen steel. The final calculated result for the query steel is taken as the average of the various estimates. The basis of the Da tabase Method is explained, and the advantages are illustrated for sel ecting engineering grades.