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Micro-scale residual stress and deformation analysis in bimetal bronze-stainless steel samples produced by laser powder bed fusion technology
Ist Teil von
Materials science & engineering. A, Structural materials : properties, microstructure and processing, 2022-11, Vol.858, p.144110, Article 144110
Ort / Verlag
Lausanne: Elsevier B.V
Erscheinungsjahr
2022
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
Additive manufacturing technologies attract significant interest as a route to fabricate structural elements with complex net shapes. 3D printing may offer the option of combining dissimilar materials within one build, like dissimilar metals in the case of laser powder bed fusion. The strength of bimetallic interfaces formed by immiscible metals such as stainless steel and copper alloys depends on the mechanism of bonding, the presence and nature of defects, and residual stresses, placing the focus of interest on the structure–mechanical performance relationship in the vicinity of the bimetallic interface. In this article, we report an investigation of laser powder bed fusion fabrication of thin plate bimetallic bronze-stainless steel samples. Sample characterization was performed using several techniques including surface topography and fractography, energy dispersive X-ray spectroscopy, electron backscatter diffraction, mechanical testing with digital image correlation mapping of strains during in situ tension inside scanning electron microscope. Spatially resolved evaluation of the local residual stress was carried out using the Korsunsky Focused Ion Beam micro-ring-core drilling method (FIB-DIC). Pure bronze and stainless steel samples fabricated separately possessed good strengths (ultimate tensile strengths of 150 MPa and 850 MPa, respectively) and significant amounts of ductility (local strains to failure of 0.8% and 1.2%, respectively), in spite of the presence of a relatively coarse and porous structure. Although the values for the bimetallic sample were somewhat reduced, they also demonstrated good mechanical properties, with the ultimate tensile strength of 105 MPa and 0.7% ductility. The fracture of bimetal takes place within the bronze at a distance of about 150 μm from the interface. The present report discusses the insights obtained, and charts the pathways towards further improvement of bimetal joint strengths through simple modifications of the laser powder bed fusion printing procedures.