The strength differential effect in different heat treatment conditions of the steels 42CrMoS4 and 100Cr6

It is well known that a number of metals show different mechanical properties under tensile and compressive loading. In case of steel this asymmetry is called “Strength Differential Effect” (SD-effect). In this work, the steels 42CrMoS4 (1.7227, AISI 4140) and 100Cr6 (1.3505, AISI 52100) are investigated in different heat treatment conditions with high and low strengths as well as different microstructures. Both, tensile and compressive stress-strain curves are compared and evaluated. It was found that the SD-effect mainly occurs in high-strength quenched and tempered conditions. A bainite condition almost shows the absence of a SD-effect. At low-strength normalized conditions a SD-effect can be observed, too. In these cases, the different length of the Lüders strain is assumed to be the reason of the SD-effect.