Load Direction-Dependent Influence of Forming-Induced Initial Damage on the Fatigue Performance of 16MnCrS5 Steel

Abstract

Forming processes influence the mechanical properties of manufactured workpieces in general and by means of forming-induced initial damage in particular. The effect of the latter on performance capability is the underlying research aspect for the investigations conducted. In order to address this aspect, fatigue tests under compressive, tensile and compressive-tensile loads were set-up with discrete block-by-block increased amplitudes and constant amplitudes, and performed up to fracture or distinct lifetimes. Aiming at the correlation of the macroscale mechanical testing results at the mesoscale, intensive metallographic investigations of cross-sections using the microscopical methods of secondary electron analysis, energy dispersive spectroscopy and electron backscatter diffraction were performed. Thereby, the correlation of forming-induced initial damage and fatigue performance was determined, the relevance of compressive loads for the cyclic damage evolution was shown, and material anisotropy under compressive loads was indicated. Finally, the need was addressed to perform further investigations regarding crack propagations and crack arrest investigations in order to clarify the mechanism by which initial damage affects cyclic damage evolution. The relevance of the principal stress axis relative to the extrusion direction was emphasized and used as the basis of an argument for investigations under load paths with different stress directions.

Performance-Related Characterization of Forming-Induced Initial Damage in 16MnCrS5 Steel under a Torsional Forward-Reverse Loading Path at LCF Regime

“…The hardness tests (HT) according to Vickers (HV) have been carried out with a testing force of 98.07 N (HV10). The device used in this study was the Shimadzu HMVG hardness testing system (HMV-G, Shimadzu, Kyoto, Japan) [20].…”

Influence of Non-Metallic Inclusions on Local Deformation and Damage Behavior of Modified 16MnCrS5 Steel

“…The RVE generated by using the EBSD data shown in Figure 2 was subjected to quasi-static tensile load with a strain rate of 10 −3 s −1 in the x-direction. [17] 375.0, 161.0, 130.0 GPa MnS-C 11, C 12, C 44 [6] 177.3, 117.0, 25.2 GPa Al 2 O 3 -C 11, C 12, C 44 [10] 496, 109, 206 [18] GPa…”

“…Moreover, Al 2 O 3 can also cause excessive wear of the tool during the machining of the component. Therefore, understanding, controlling, and utilizing the limiting effects of these two inclusions can assist in the material forming processes and producing application-based materials [18][19][20].…”