Influence of Deformation-Induced alpha prime Martensite on the Crack Initiation Mechanism in a Metastable Austenitic Steel in the HCF and VHCF Regime
Fatigue failure in the VHCF regime of high strength steels is dominated by subsurface crack initiation around non-metallic inclusions with fisheye fracture morphology.However,this unique failure mechanism cannot be thoroughly confirmed for metastable austenitic steel 1.4301 (AISI 304),for its crack origin is heavily dependant on fatigue life and its amount of deformation-induced alpha prime martensite.In the HCF regime cracks originate at the specimen surface from inclusions exceeding 0.02 mm,irrespective of the volume fraction of deformation-induced alpha prime martensite.For a volume fraction beyond VM = 30% the higher notch sensitivity of the martensite phase can lead to crack initiation at micro flaws at the surface.In the VHCF regime the influence of the martensite content is even more dominant,as for VM = 54% the crack origin shifts to subsurface inclusions.While the formation of a fine granular area is observed for all cases with VM > 50%,the occurrence of a typical fisheye morphology depends on the inclusions relative position to the specimens surface.The diversity of crack initiation mechanisms can be explained by the interaction of the austenite and martensite phases and its different ductilities with the inclusions as shown by TEM micrographs and Murakamis model of hydrogen-induced VHCF failure.
Very high cycle fatigue metastable austenitic steel deformation induced martensite fisheye fracture
Martina Zimmermann A.Grigorescu C.Müller-Bollenhagen H.-J.Christ
Institut für Werkstoffwissenschaft,Technische Universit(a)t Dresden,Dresden 01062,Germany Institut für Werkstofftechnik,Universit(a)t Siegen,Siegen 57068,Germany Continental Teves AG & Co.oHG,Hannover 30419,Germany
国际会议
北京
英文
1-9
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）