Microstructural effects on high-cycle fatigue properties of microalloyed medium carbon steel 38MnVS

High cycle fatigue behavior of V-microalloyed medium carbon steels: A comparison between bainitic and ferritic-pearlitic microstructures

“…For the smooth specimens of both tested steels, all the fractures were originated from specimen surface through slip band extrusions/intrusions mechanism, which implies that microstructure plays a controlling role in fatigue crack initiation [19]. This result is in agreement with that reported for the HCF behavior of MA medium carbon steels [19,20]. As expected, all the fractures were initiated from notch root for the notched specimens.…”

“…It is worth noting that BA steel not only exhibits higher σ w , but also comparable or even higher σ w /R m with those of commonly used Q&T medium carbon and low alloy structural steels such as 45, 40Cr and 42CrMo at similar strength level as can also seen from Figs.8(a),(b) [19,25,26].…”

“…is ~40%. This is mainly attributed to much high forging ratio, low finishing forging temperature and fast post-forging cooling of small finishing size rod [19,23]. TEM and XRD examinations revealed that there were plenty of finely dispersed V carbonitride V(C,N) particles distributed within both proeutectoid ferrite and pearlitic ferrite (see Reference [19] for more details).…”

“…This is mainly attributed to much high forging ratio, low finishing forging temperature and fast post-forging cooling of small finishing size rod [19,23]. TEM and XRD examinations revealed that there were plenty of finely dispersed V carbonitride V(C,N) particles distributed within both proeutectoid ferrite and pearlitic ferrite (see Reference [19] for more details). Moreover, There are notable amount of intragranular ferrite (IGF) -7 -idiomorphs within austenite grains, which has been confirmed to be associated with MnS inclusions and V(C,N) particles [3].…”

“…In recent years, the need for vehicles' weight reduction leads increasing demands for increasing strength, especially for increasing fatigue strength, of MA medium carbon steels. Therefore, increasing attentions have also been paid to fatigue fracture behavior of MA medium carbon steels for a proper selection or replacement of materials besides strength and toughness [2,[13][14][15][16][17][18][19][20]. Moreover, many actual forged components contain inevitable geometrical slight discontinuities or generally term of notches, which could generate local stress and strain concentrations in the notch area when are loaded.…”