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A finite element microstructure model with permeability tensors that considers crystallographic texture and grain size based on magnetic domain theory has been developed for the evaluation of magnetic anisotropy in polycrystalline steels. The model has proved capable of capturing the crystallographic texture, the grain size and the vector induction effects on the effective permeability behaviours for typical textures in steels. The predicted magnetic properties as a function of the magnetic field direction enables a quantitative characterisation of the magnetic anisotropy. The predicted effective permeability maps can serve as a visual indication of the crystallographic texture from magnetic values. These features have been experimentally validated against a commercial grain oriented electrical steel featuring strong texture and magnetic anisotropy. [ABSTRACT FROM AUTHOR]

The boundary conditions for describing the mass transfer of carbon from a low-pressure oxygen-free atmosphere into steel under vacuum carburizing are analyzed. Experimental results and thermodynamic calculations are used to determine the numerical value of the activity of carbon in an environment of low-pressure acetylene. The calculated value of the carbon potential is used in the boundary condition of kind III in the form of a Langmuir expression applied to a mathematical model of vacuum carburizing based on numerical solution of the diffusion equation. The calculated concentration profiles are shown to describe adequately the experimental results. Different nonequilibrium processes of vacuum carburizing of steels are shown to have similarity. [ABSTRACT FROM AUTHOR]

The paper presents the results of tribotechnical tests of nitrided and carburized steels according to schemes simulating heavily loaded couplings: a pair of reverse sliding friction at loads up to 40 MPa and a pair of rolling friction with slipping in accordance with GOST 25.501–78 performed in order to assess the limit of contact endurance. The wear intensity (Ih), friction coefficient (f), and maximum permissible load (Pd), which determines the bearing capacity of the contact, and the critical pressure (Pcr), at which seizure are formed, are evaluated. It is shown that at a sliding speed of 0.19 m/s we have Рadm = 40 MPa, Рcr ≥ 40 MPa, Ih = 0.8 × 10–9, and f = 0.10 for a pair with a nitrided layer and Рd = 20 MPa, Рcr = 25 MPa, Ih = 1.4 × 10–9, and f = 0.13 for a pair with a cemented layer. The extreme pressure resistance, estimated by the value of the critical pressure, is 25–30% higher for pairs with a nitrided sample. For rolling conditions with slipping, the limit of contact fatigue of 16Kh2R3MFBAU-Sh and 20Kh3R3MBF-Sh nitrided steels is at the level of contact endurance of 18Kh2R4V-Sh carburized steel. The wear rate of iron nitrides is 2–3 times lower than that of the diffusion zone, the critical pressure increases, and the durability of the friction pair increases several times. From the standpoint of the thermodynamics of dissociation of Fe2–3N, Fe4N, and Fe3C at elevated temperatures in the contact spots, a hypothesis of the nature of the higher critical pressure of nitrided steels is put forward. [ABSTRACT FROM AUTHOR]

In recent years, increasing demand for biodegradable lubricants has been observed in precision machining owing to ISO 14000, which draws more attention toward the operator's health and environmental issues. In this context, vegetable oils are adopted as eco-friendly lubricants in sustainable lubrication techniques such as Small Quantity Lubrication (SQL). The grinding performance and surface integrity of AISI H13 die steel may also be improved via SQL. The present study aims at revealing the best lubricant for work material by comparing the lubricating characteristic of vegetable oils like castor, groundnut, sunflower, and soybean. The lubrication characteristics were studied in terms of force ratio, surface roughness, surface topography, microchip morphology, and wettability. Experiential results revealed that castor oil exhibited superior lubricating performance, including the lowest force ratio and surface roughness (Rɑ: 0.147 µm and Rz: 1.122 mm), and outstanding surface quality. Furthermore, the wide bearing area (BC) curve and a higher BC ratio (81.76%) indicated the development of an excellent antifriction ground surface in the case of castor oil. The spherical and burnt chips were observed at an infeed of 32 µm in the case of soybean oil. The viscosity of the lubricant significantly influenced the wettability. The lower viscous soybean oil promoted better lubricant wettability in the machining zone. [ABSTRACT FROM AUTHOR]

A widespread implementation of large scale additive manufacturing (AM) processes, such as wire arc-directed energy deposition (WA-DED) AM can transform the current manufacturing supply chain networks. Naturally, such implementation requires control of the microstructural attributes, such as texture and phase evolution in the processed alloys. Currently, the texture evolution in fusion-based AM (F-BAM) processes is majorly rationalized by the phenomena occurring only during solidification. However, such rationalization is insufficient for understanding the evolution of primary and secondary crystallographic orientations, and consequently, fails to offer a comprehensive understanding and control of overall texture in F-BAM processed alloys. To this end, we report a single crystal (SX)-like texture in WA-DED processed SS316L for the first time. Furthermore, we assess the physical phenomena that may lead to such unique microstructural evolution during WA-DED AM. Subsequently, using microstructural characterization spanning the build height and thermomechanical simulations we investigate the effect of competitive growth and epitaxial growth occurring during solidification and thermally induced plastic deformation occurring post solidification on the overall texture of WA-DED processed SS316L. A spatial variation in solidification pathway is also established and correlated with variation in undercoolings across the build. Tensile tests revealed a strong orientation dependence of deformation mechanisms with over 110% elongation to failure of specimens deformed along <011>. Such anisotropy is rationalized using Schmid's analysis of dislocation slip and deformation twinning. Overall, the mechanisms outlined in this work will facilitate an enhanced understanding and subsequent control of texture evolution, solidification behavior and mechanical behavior of WA-DED processed steels. [Display omitted] • A SX-like texture is reported in a directed energy deposition processed SS316L. • Phenomena occurring during and post solidification affect texture in DED. • Tip temperatures of γ and δ phases and solidification modes vary with build height. • Stray-grain formation is rationalized using spatially varying thermokinetics. • Orientation dependent behavior of leading/trailing partials leads to anisotropy. [ABSTRACT FROM AUTHOR]

Prior-austenite grain (PAG) structures play a critical role in determining steel microstructures and properties. Over recent years, the use of algorithms that reconstruct PAGs from electron backscatter diffraction (EBSD) measurements of martensitic or bainitic microstructures have become commonplace. These appear to work well, but there has yet to be a comparison made of the reconstructed PAG microstructure to the true PAG microstructure of a steel measured above Ae3 before transformation. Here, in-situ EBSD was used to record the austenite grain structure (at 1000 °C) before transformation, as well as the progress of subsequent martensitic and bainitic transformations. The resulting dataset, which we have made available to the community here: https://doi.org/10.5281/zenodo.8348372 , was used to assess of two popular algorithms for PAG reconstruction. They were found to be accurate enough for PAG size measurement and general texture analysis, although the exact morphologies of some PAG and twin boundaries are sometimes lost. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper presents a study that combines experimental and numerical approaches to investigate hybrid joining methods involving riveting and adhesive bonding, aimed at enhancing mechanical properties by leveraging their advantages while addressing their limitations. The primary focus of this research was to address the issue of reducing adhesive pockets that commonly occur in such processes. To address this, an experimental setup was developed, enabling precise and reproducible measurements of deflections using digital image correlation (DIC). This allowed for accurate assessment of the extent of adhesive pockets. The device was designed, fabricated, and effectively validated through testing. The findings revealed that employing thicker sheets led to a reduction in adhesive pockets due to minimized sheet deformation and improved adhesive flow. Conversely, increased lengths resulted in the opposite effect. A comparison of materials with the same thickness but varying yield strength indicated minor differences in deflections. Subsequently, the experimental results were subjected to numerical modelling using two distinct methodologies. The first approach employed a Coupled Euler–Lagrange (CEL) framework, while the second employed Smoothed Particle Hydrodynamics (SPH). Prior to application, both methods were validated through squeeze-flow experiments. The numerical modelling utilizing the CEL approach outperformed the SPH method, offering a more accurate estimation of deflections. Finally, predictions of deflections were generated using a simplified analytical approach that incorporated the intricate rheological behaviour of the adhesive, accounting for loading-rate effects. This yielded satisfactory agreement between the predicted and experimental data, particularly at the centre of the specimen, with some deviation towards the edges. [ABSTRACT FROM AUTHOR]

This study examines grouted joints for offshore wind turbine systems, where gaps between steel pipes are filled with grout, relying on adhesion, friction and compression struts formed by shear keys. Concerns about the limited load carrying capacity of large diameter grouted joints in offshore structures have prompted investigation. Whilst adhesive bonds are recognized for load transfer in structural steel, the complete replacement of grouting with bonding alone is proving impractical for large gaps in offshore structures, posing challenges in terms of cost and handling. To address these challenges, the study presents an innovative hybrid grouted joint for steel structures that combines grout and adhesive layers. This novel approach replaces traditional large shear keys with distributed micro-shear keys — small granules embedded in the grout material. Under axial loading, the hybrid joint demonstrates robust performance, with a maximum nominal shear stress on the inner pipe of 30.1 MPa and consistent load capacity across tests. Average shear strength is in line with, and occasionally exceeds, expectations. Notably, the hybrid joint shows resilience in different configurations and maintains a low coefficient of variation of 5.5%, indicating consistent performance. When the influence of the adhesive material on the hybrid joint is examined, the effect on the joint stiffness is minimal, despite variations in adhesive stiffness. Sikadur 370, which has a higher modulus of elasticity than DuploTEC, shows similar deformation curves in the elastic region, emphasizing the robustness of the joint. Differences in the maximum loads are attributed to the thickness of the adhesive layer and the lower modulus of DuploTEC, resulting in different shear strengths. The proposed hybrid joint offers a promising solution to improve the performance of conventional grouts and adhesives in offshore structures. The study also formulates a failure criterion, performs numerical stress analysis, and models the effect of geometric dimensions, eccentricity, and misalignment on load capacity. The methodology's accuracy in predicting load capacity, supported by numerical analysis and large-scale joint simulations, contributes to a comprehensive understanding of hybrid joint performance in engineering applications. [ABSTRACT FROM AUTHOR]