Fatigue strength, crack initiation, and localized plastic fatigue damage in VHCF of duplex stainless steels
2015 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 7, 899-910 p.Article in journal (Refereed) Published
The fatigue strength of two-duplex stainless steel grades, 2304 SRG and LDX 2101, with austenitic–ferritic microstructure is tested using ultrasonic fatigue testing equipment operating at 20 kHz. The testing is conducted in tension-compression mode with the load ratio R=-1. The fatigue strength is evaluated at 107, 108, and 109 load cycles and the estimates of fatigue strength are higher for the LDX 2101 grade. The fatigue crack initiation mechanisms are analyzed using a scanning electron microscope. The fatigue cracks, in all cases, appear to initiate due to accumulation of plastic fatigue damage at the surface. In the 2304 SRG grade, accumulation of fatigue damage occurs at the external surface of fatigued specimens in the form of extrusions at the grain/phase boundaries and in the form of individual slip lines in the austenite phase. Meanwhile, in the LDX 2101 grade accumulation of plastic fatigue damage in the form of extrusions and intrusions occurs mainly within the ferrite grain. When the crack is microstructurally short, the crack growth appears to be crystallographic in nature and the crack appears to change its direction propagating from one grain into another.
Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2015. Vol. 87, no 7, 899-910 p.
duplex stainless steel; ultrasonic fatigue testing; plastic fatigue damage; very high cycle fatigue; crystallographic crack growth
Metallurgy and Metallic Materials
Research subject Materials Engineering; Mechanical Engineering
IdentifiersURN: urn:nbn:se:kau:diva-38693DOI: 10.1002/srin.201500263OAI: oai:DiVA.org:kau-38693DiVA: diva2:873311
ProjectsVery High Cycle Fatigue of Stainless Steels - an unknown life