Triple Self-Sorting in Constitutional Dynamic Networks: Parallel Generation of Imine-Based CuI, FeII, and ZnII Complexes

Three imine‐based metal complexes, having no overlap in terms of their compositions, have been simultaneously generated from the self‐sorting of a constitutional dynamic library (CDL) containing three amines, three aldehydes, and three metal salts. The hierarchical ordering of the stability of the three metal complexes assembled and the leveraging of the antagonistic and agonistic relationships existing between the constituents within the constitutional dynamic network corresponding to the CDL were pivotal in achieving the sorting. Examination of the process by NMR spectroscopy showed that the self‐sorting of the FeII and ZnII complexes depended on an interplay between the thermodynamic driving forces and a kinetic trap involved in their assembly. These results also exemplify the concept of “simplexity”—the fact that the output of a self‐assembling system may be simplified by increasing its initial compositional complexity—as the two complexes could self‐sort only in the presence of the third pair of organic components, those of the CuI complex

Low Cycle fatigue behaviour of two Al-Li alloys.

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Mechanistic studies on type 300 stainless steels manufactured by Hot Isostatic Pressing:The impact of oxygen involvement on fracture behaviour

With near-net shape technology becoming an increasingly desirable route toward component manufacture due to its ability to create components with increasingly complex geometries, minimizing the number of potential welded joints, as well as reducing machining time and associated costs, it is important to demonstrate that components fabricated via Hot Isostatic Pressing (HIP) are able to perform to similar standards as those set by equivalent forged materials. Hot Isostatically Pressed (HIP’d) materials are typically accredited with displaying enhanced yield strengths, ultimate tensile strengths, and ductility over their forged counterparts. In this paper we explore the effects of oxygen, which resides in the austenite matrix during the HIP manufacture process, on a material’s fracture toughness properties. We quantify the influence of different concentrations of oxygen on both the microstructural and mechanical properties of HIP’d 304L and 316L stainless steel, highlighting the benefit of reducing the oxygen as much as possible. Various mechanical tests have been performed on materials containing a range of oxygen contents (between 100 ppm and 200 ppm) and over a large temperature range, including J1C fracture toughness testing, instrumented Charpy, and tensile, and the mechanistic involvement of residual oxygen on the results is discussed. The effects of oxygen become more apparent at cryogenic temperatures, whereas the fracture behavior of HIP’d and forged variants of 304L and 316L at elevated temperatures appears to be comparable.</jats:p

Tribological behaviour and tool wear analyses in rough turning of large-scale parts of nuclear power plants using grooved coated insert

International audienceThe tribological behaviour and tool wear mechanisms in rough turning, using coated grooved insert, of a large-scale part, made of 18MND5 steel used for steam generators of nuclear power plants, have been analysed. Characterisation of the insert rake face, using various techniques (SEM, \EDS\ and Profilometer), has revealed an intense thermomechanical loading with wear localisation at particular zones, and formation of an adhered thin tribo-layer. A numerical model has been developed to predict finely the tool wear as revealed by experimental observations. The main findings concern the prediction of contact discontinuities and where the wear is highly localised as well as thermomechanical conditions causing observed phenomena, like adhesion of the workmaterial on some zones on the rake face. Contact discontinuities are attributed to the complex geometry (presence of concave zones) of the coated grooved insert, designed especially to reduce the tool–chip contact area and to promote the chip breakage. Other cutting parameters, like the specific cutting force and chip morphology parameters are also well predicted. This is a contribution to understand wear mechanisms occurring on complex cutting inserts at high material removal rate (moderate cutting speed, but high depth of cut and feed rate)

Characterization and Modelling of the Rough Turning Process of Large-scale Parts: Tribological Behaviour and Tool Wear Analyses

AbstractMachining large-scale parts in several industries (nuclear, naval, energy…) is a challenge for machine tools operators. Various problems are encountered, like respecting specified dimensions, deformation of the workpiece during machining, limit of the cutting speed, excessive tool wear, etc. All these difficulties are related to the large size of the machined part, which may have several meters and weigh several hundred kilograms. This study focuses on analysis of the rough turning process of a shell component, having few meters, as a part of steam generators of nuclear power plants. During the rough turning step, a high material removal rate (moderate cutting speed, but high depth-of-cut and feed rate) is necessary to achieve the workpiece in reasonable time. Experimental and theoretical analyses are conducted to highlight the intense thermomechanical loading at the tool–workmaterial interface. Revealed physical phenomena at the tool rake face, like adhesion and abrasive wear types, using various characterization techniques, are reproduced by a numerical model developed to simulate the cutting process. As an interest result, contact discontinuities at the tool–chip interface as well as where the wear is highly localized are well predicted as observed on scanning electron microscope. These contact discontinuities are attributed to the grooved rake face of the insert, designed with a chip breaker to reduce the tool–chip contact area and to promote the chip fragmentation. This study can be helpful for the design of rough turning inserts, by analysing the effectiveness of the rake face geometry (contact area, chip breaker…)