Heat treatment / mechanical properties

Optimal mechanical properties may be attained by quenching and tempering, in which the steel is first hardened by holding the steel at a temperature between 1020 and 1070°C followed by quenching in air, oil or polymer. The tempering temperature is dependent on the desired strength. In most cases a tempering treatment in the temperature range 640 to 740°C followed by air cooling produces the required properties. In this condition, the following mechanical proper- ties can be expected:

Property  Spec QT800  Typical

- yield strength (N/mm 2 )  R p0,2 : ≥ 600 

- tensile strength (N/mm 2 )  R m : 800 – 900 

- tensile elongation (%)  A 5 : ≥14 

- impact energy (J)  @ 25°C ISO-V : ≥50J

Property  Spec QT900

- yield strength (N/mm 2 )  R p0,2 : ≥ 700 

- tensile strength (N/mm 2 )  R m : 900 – 1050  960

- tensile elongation (%)  A 5  :  ≥11