On a classical CrV-bearing spring steel 50CrV4 (1.8159) the effects of
thermomechanical treatment (TMT) and additional microalloying with ti
tanium and niobium on the processes in austenite were investigated. Th
e aim of this study was to achieve an austenite state, that promises -
after subsequent quench and tempering- mechanical properties of spring
steels superior to those after conventional treatment. For laboratory
tests the hot deformation simulator Wumsi was employed. It was found
that after reheating to usual austenitization temperatures the austeni
te microstructure of steel 50CrV4 is widely uninfluenced by the initia
l as-delivered microstructure. Despite the finer austenite grain size
occurring after austenitization, additional microalloying with Ti and
Nb raises the recrystallization temperature considerably. The finding
that the incubation time of austenite recrystallization can be prolong
ed up to several minutes by microalloying is decisive for the practica
l applicability of TMT. In this way the substructured state of polygon
ized austenite beneficial for martensite formation can be preserved ov
er the time needed for additional production steps between hot rolling
and hardening of leaf springs. Moreover, the deformation of a not rec
rystallizing austenite may favourably influence the distribution of un
desirable tramp elements in spring steels.