Effect of notches on the deformation behavior and damage evolution of additively manufactured 316L specimens under uniaxial quasi-static and cyclic loading

•The yield strength of notched structures is barely dependent on notch geometry.•Local plasticity leads to reduction of notch induced stress concentrations.•The lifetime to failure shows clear dependence on notch geometry.•Local defects can superimpose notch effects under cyclic load.•Filigree struc...

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Bibliographic Details
Published in:International journal of fatigue 2019-10, Vol.127, p.175-189
Main Authors: Brenne, F., Niendorf, T.
Format: Article
Language:English
Subjects:
Additive manufacturing
Austenitic stainless steels
Brittle materials
Cyclic loads
Deformation effects
Deformation mechanisms
Digital imaging
Electron backscatter diffraction
Evolution
Fatigue behavior
Materials fatigue
Mechanical properties
Microstructural analysis
Notch effect
Notches
Powder beds
Selective laser melting
Stress concentration
Surface roughness
Tensile testing
Titanium base alloys
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Summary:•The yield strength of notched structures is barely dependent on notch geometry.•Local plasticity leads to reduction of notch induced stress concentrations.•The lifetime to failure shows clear dependence on notch geometry.•Local defects can superimpose notch effects under cyclic load.•Filigree structures have lower strength and crack initiation resistance. Powder bed based additive manufacturing techniques enable for fabrication of filigree and geometrically complex structures. These structures typically are characterized by many cross section transitions, leading to notch induced stress concentration. Furthermore, the process induced surface roughness cannot be always mechanically removed as the surfaces are not accessible using conventional tools. Although these factors are critical for many different applications and materials, previous works mainly focused on notch effects in brittle materials, such as the common Ti-6Al-4V alloy. Systematic examination of notch induced stresses in ductile materials, especially under the constraints of process induced surface roughness and small part dimensions, was not conducted. Thus, the present study addresses these issues by evaluation of the mechanical performance of notched samples made of 316L stainless steel under quasi-static and cyclic loading. By means of digital image correlation insights into the local deformation mechanisms and the damage evolution, respectively, were obtained. Microstructural analysis by electron backscatter diffraction provided profound explanation for the phenomena observed.
ISSN:0142-1123
1879-3452
DOI:10.1016/j.ijfatigue.2019.05.018