Manganese Alloyed Q & T Steel with high Hardenability for Forging Parts with large Diameters

A new quenching and tempering steel is presented and compared with reference alloys 42CrMo4 and AISI 4140. Through the substitution of chromium (− 0.7 wt.-%) by manganese (+ 1.3 wt.-%) high hardness could be guaranteed by reduced alloying costs. Hardness gradients are shown in the Jominy-test for the reference alloys, while the new alloy shows nearly a constant hardness of 600 HV10. The inductive hardenability was tested using a dilatometer. The new alloy shows a hardness of 780 HV which is 60 HV10 higher than the reference alloys. The critical cooling rate was reduced from 19 K/s for the reference alloys to 9 K/s for the new alloy.