Case-hardened and quenched and tempered steels with the promised hardenability

Case-hardened and quenched and tempered steels have a broad range of applications, from crankshafts and camshafts to gear parts (disk springs, clutch plates) and far beyond. These steels must therefore possess material properties that are changed by heat treatment in such a way that, for example, the hardness, strength and toughness are optimally adapted to the different conditions for the particular use.
 
Guaranteed hardness scatter bands can be specified for these steels. The hardenability of case-hardened and quenched and tempered steels is determined in end quenching tests or by using calculation formulas. The corresponding limits are given in DIN EN 10084 or DIN EN 10083-3. The term +H there   indicates requirements for normal hardenability, +HH for a hardness scatter band restricted at the lower end and +HL for a scatter band that is restricted at the upper end. The figure show the different scatter bands for a typical case-hardened and quenched and tempered steel: 16MnCr5.