Heat treatment of steel workpieces - comprising cooling from the austenitisation temp in a heated bath

摘要

Macro- and micro-stresses in steel are relieved by effecting the cooling from the austenitisation temp. in a bath having a temp. below the starting temp. of martensite formation in the range of the lowest possible inter. transformation, and keeping the workpieces in the bath until 10-20% martensite is formed and the remaining austenite is isothermally transformed into the lowest inter. structure grade. The residence time at temp. below the Ms point should be at least 3 times the transformation time in the intermediate step at this temp. to improve the toughness of the steel.