Textured glass is used in a wide range of applications to improve optoelectrical performances, such as photovoltaics, biosensing, microfluidics, and photonics. Honeycomb textures have demonstrated an excellent performance in optical devices using crystalline silicon wafers as opaque substrates. As a pathway to translate these advantages to configurations implementing glass, hexagonal-shaped microsized craters (honeycombs) are made on glass in this study. We use photolithography combined with wet etching for this process. The relationship between photoresist mask design, glass–photoresist adhesion, wet-etching steps, and the mechanism of honeycomb formation is studied. It is demonstrated that the higher the isotropic nature of etching achieved, the deeper the hexagonal craters will be. The potential of hexagonal textures on glass to significantly reduce reflection to <8% over the entire spectral range is observed. Finally, hexagonal microsized textures with 5 μm periodicity and 1.01 μm depth that effectively diffuse 50% of the total transmitted light at near-infrared (1100 nm) wavelengths are developed.

Wire arc additive manufacturing (WAAM) of high-strength steel (HSS) has gained significant attention for structural applications. Achieving precise control over the manufacturing process and understanding the relationship between process parameters and the resulting material characteristics is crucial for optimizing the performance of these steel walls to achieve tailored properties. The present study was performed to comprehend the influence of process parameters on the microstructure and properties of wire arc additively manufactured (WAAM) high-strength steel (HSS) thin-wall structures. Multi-layer thin walls of ER110S-G high-strength steel comprising 30 layers were deposited bidirectionally and were fabricated with different travel speeds and wire-feed rates. Geometrical analysis conducted on samples indicates that achieving minimal surface waviness for single-bead thin walls depends on adjusting wire feed rates and travel speeds. Specifically, lower wire feed rates are found to be more effective in minimizing waviness when dealing with single-bead thin walls (thickness < 5 mm). Conversely, lower travel speeds are preferred for reducing surface irregularities in walls fabricated at high deposition rates for thicker single-bead walls (thickness > 8 mm). Cooling rate analysis from midpoints of the 5th, 15th and 25th layers of each sample indicates high cooling rates for low heat input (HI=178 J/mm) samples even for the 25th layer. Microstructural characterization of the samples suggests an increase in acicular ferrite and martensite volume fraction with lower heat input. Additionally, microstructural quantification with EBSD reveals smaller grain sizes and higher Kernel average misorientation for low heat input deposits. Mechanical properties like hardness and tensile strength display an increasing trend with decreasing heat input while elongation to fracture is reduced under the same conditions. Furthermore, anisotropic behaviour is observed in tensile strength and elongation to fracture between building and deposition directions due to the presence of microstructural inhomogeneities.

Additive manufacturing offers a significant potential for producing metallic parts with distinctly localised microstructures and mechanical properties, commonly known as functional grading. While functional grading is generally accomplished through compositional variations or in-situ thermo-mechanical treatments, variation of process parameters during additive manufacturing can offer a promising alternative approach. Focusing on the electric arc-based additive manufacturing process, this work focuses on the functional grading of high-strength steel (S690 grade) by adjusting the travel speed and inter-pass temperature. Through a combination of thermal simulations and experimental measurements on single bead-on-plate depositions, it is shown that the microstructure and the mechanical properties of parts can be controlled through the rational adjustment of process parameters. A rectangular block was fabricated to demonstrate functional grading using a constant wire feed rate and varying travel speed. The rectangular block consisted of a low heat input (LHI) region deposited between high heat input (HHI) zones. A graded microstructure was obtained with the HHI zones composed of a mixture of polygonal ferrite, acicular ferrite, and bainite, while the LHI region was primarily composed of martensite. The hardness and profilometry-based indentation plastometry measurements indicated that the LHI region exhibited higher hardness (32%) and strength (50%), but lower uniform elongation (80%), compared to the HHI zones. The present study demonstrates the potential to achieve functional grading by adjusting process parameters in electric arc-based additive manufacturing, providing opportunities for tailor-made properties in parts.

Laser beam shaping offers remarkable possibilities to control and optimise process stability and tailor material properties and structure in laser-based welding and additive manufacturing. However, little is known about the influence of laser beam shaping on the complex melt-pool behaviour, solidified melt-track bead profile and microstructural grain morphology in laser material processing. A simulation-based approach is utilised in the present work to study the effects of laser beam intensity profile and angle of incidence on the melt-pool behaviour in conduction-mode laser melting of stainless steel 316L plates. The present high-fidelity physics-based computational model accounts for crucial physical phenomena in laser material processing such as complex laser–matter interaction, solidification and melting, heat and fluid flow dynamics, and free-surface oscillations. Experiments were carried out using different laser beam shapes and the validity of the numerical predictions is demonstrated. The results indicate that for identical processing parameters, reshaping the laser beam leads to notable changes in the thermal and fluid flow fields in the melt pool, affecting the melt-track bead profile and solidification microstructure. The columnar-to-equiaxed transition is discussed for different laser-intensity profiles.

Wire and Arc Additive Manufacturing (WAAM) emerged as a manufacturing process for large scale structures with extensive form and design freedom. WAAM can be fully exploited once the relation between the transient thermal history and its relation to microstructure development and resultant mechanical properties is established. This relation can be further used for computational design tools such as Topology Optimization. This paper presents a model to predict the relation between the thermal history and solid-state phase transformations in a widely applicable High Strength Low Alloy steel ER110S-G. The transient thermal history of parts manufactured by WAAM is modelled using finite element analysis. The modelled thermal history is validated with thermocouple measurements. Our results show that a critical cooling cycle is responsible for the solid-state phase transformation in an AM part. The cooling rate of this particular cooling cycle is superimposed onto an experimentally constructed Continuous Cooling Transformation (CCT) diagram to determine the local solid-state phase fractions. The predicted phase fractions in three wall samples with different design and processing conditions of AM parts are used to predict the hardness. The predicted hardness is 10% higher than the measured hardness of AM samples. The effect of tempering is also considered in the model through JMAK equation. The results show that the tempering is caused in regions with high martensite content and it lowers the hardness by 8 − 10%. The micrographs of the AM parts show that the microstructural features are same for the AM parts with similar critical cooling rates.