Papers by Keyword: Microstructure Analysis

Abstract: This study presents a comparative analysis of manufacturing techniques for 316L stainless steel, focusing on Direct Energy Deposition (DED) and traditional casting methods. The research aims to evaluate the differences in microstructure, mechanical properties, and overall performance of components produced by these two distinct processes. Through a series of experiments and material characterizations, including microscopic examinations and mechanical testing, we investigate how the manufacturing techniques influence the final properties of 316L stainless steel. Our findings reveal significant variations in grain structure, porosity, and tensile strength, highlighting the advantages and limitations of each method. This comparative study provides valuable insights for industries seeking to optimize their manufacturing processes for high-performance applications, ultimately contributing to the advancement of additive manufacturing technologies and traditional casting techniques.

Abstract: This study examines the effects of borax/boric treatment on the microstructure and engineering properties of Dendrocalamus asper bamboo, evaluating its suitability as a sustainable construction material. Four types of bamboo—new and aged samples, treated and untreated—were assessed for moisture content, dry density, compressive, and shear strength. Microstructural analysis showed that borax/boric treatment helps preserve cellular structure and stability, especially in new bamboo. Mechanical testing revealed higher compressive strength in treated new bamboo (497.9 ksc) compared to untreated bamboo, and greater integrity in aged treated bamboo over a 10-year period. Untreated bamboo exhibited deterioration, including cracks and insect damage, absent in treated samples. These findings demonstrate that borax/boric treatment improves bamboo’s initial strength and long-term durability, supporting its use in structural applications and promoting sustainable construction with bio-based materials.

Abstract: The main interest in Additive Manufacturing, specifically Powder Bed Fusion - Laser/Metal (PBF-L/M) technology relates to its ability to produce complex components with significant weight reduction using the minimum material required by the application. Being the aerospace sector one of the sectors where this technology has more interest and applications, particularly the Ti-6Al-4V alloy, ensuring the quality of parts thus the processed material becomes more critical since the criticality of the using powder affects directly.This study aims to analyze the effect of powder reuse on titanium alloy Ti‑6Al‑4V manufactured by PBF-L as well as the material processability when a significant processing parameters optimization is conducted by modifying the laser scan speed for the process efficiency by keeping the energy density without compromising the material performance. The chemical composition and the physical properties of specimens manufactured with virgin powder and after several build jobs are analyzed and compared to assess the influence of virgin and reused powder material on the consolidated material.Furthermore, the manuscript also provides perspectives and recommendations to enable AM users to develop a well-defined and standard powder reuse process to maintain the desired characteristics' consistency. By optimizing the laser parameters, both manufacturing efficiency and material behavior can be improved. Fatigue and tensile testing should be done too to prove this after several heat treatments in different conditions, to improve alloy properties and minimize residual stress at the same time.Finally, it is worth mentioning that the development carried out around this dual-phase Ti alloy has contributed to some parts manufacturing of structural components for aerospace applications. Hence, the material performance has a long journey ahead of that industry.

Abstract: Investigating the microstructures of materials with microscopy is a key task in quality assurance, the development of new materials, and the optimization of manufacturing processes. However, conventional image analysis often demands significant time for analysis and a large volume of images, and the predictions produced are commonly constrained. Applying deep learning, models can be trained to analyze material microstructures quickly and with greater accuracy. The objective of this study is to provide a method for the automatic segmentation of microstructural images obtained from microscopes or scanning electron microscopes using Convolutional Neural Networks. For this purpose, two software scripts were developed in Python employing OpenCV and the fastai library. The first script is designed to generate reference images, while the second is utilized for training a model and predicting the microstructure in an image. The test of the microstructural analysis using the developed software tools demonstrates that robust prediction results are attainable by using high-quality reference images. This tool has been made available as an open-source on GitHub for public use in materials analysis and can be enhanced and further developed if required.

Abstract: This research focuses on development of infra-lightweight foamed concrete with very low density. The first step is to manufacture stable preformed foam with optimizing the applied air and water pressure as well as the foaming agent dosage. Then, an appropriate mixing procedure of infra-lightweight concrete is developed. In the experimental plan, 8 different mixes are prepared and tested with different densities, 200, 300, 500, 600 kg/m³. Two values of w/c ratio are used, 0.6 and 0.4. A superplasticizer compatible with the foaming agent is used in the second case (w/c 0.4) in order to achieve the required workability. Compressive strength, thermal conducting and scanning electron microcopy (SEM) measurements have been measured in order to characterize the developed foamed concrete. The experimental results show that for infra-lightweight foamed concrete, the material density is the main parameter governing its compressive strength and thermal conductivity. The SEM observations provide evidences confirming the results of compressive strength and thermal conductivity. The role of w/c is insignificant on compressive strength and thermal conductivity of such type of concrete with very low density. The findings of this investigation revealed that infra-lightweight concrete with self-leveling ability, appropriate strength and different densities can be produce with giving more concern to the performed foam characteristics as well as the mixing technology.

Abstract: The lightweight composition, non-magnetic nature, and machinability of aluminum alloy A356 make it an important material in many industries due to its significant mechanical properties such as strength, ductility, fatigue resistance, and castability. Aluminium alloy forms an oxide layer when exposed to air. The microstructure of this alloy plays a critical role in determining its mechanical behavior. This study utilized aluminum alloy A356, composed of 92.05% aluminum, 7% silicon, 0.35% magnesium, 0.20% copper, 0.10% manganese, and 0.10% zinc. This alloy exhibits extremely high corrosion resistance, similar to stainless steel, with a melting point of 650°C. The study examines multi- component (mainly Al with Si) A356 containing small amounts of Mg, Cu, Mn, and Zn for their complex microstructural behavior. It includes observations using techniques such as optical microscopy and X-ray diffraction (XRD). This research was carried out to investigate different areas of the same metal’s microstructure and to discover the influence of cooling rates during the solidification process. The findings revealed that there are dissimilarities between the central parts and outer areas, as well as similarities between the two side portions. Also, this study highlights processing conditions’ impact on the material response while looking at heat transfer rate effects during solid-state transformation. The findings of this study highlight the presence of distinct microstructures (dendritic and equiaxed structures) across different sections of the cast Aluminum alloy A356. These findings contribute to a better understanding of the microstructure-property relationship of Aluminum alloy A356, assisting in improvising design and manufacturing processes for enhanced performance.

Abstract: This study evaluates the impact of adding metalized plastic waste (MPW) fibers to lightweight concrete that is used as a filler material in building slopes and bridge ramps. The goal is to open up new opportunities for recycling plastic waste and promote a more sustainable and productive construction industry. This study examined the mechanical behavior of lightweight concrete (LC) at 3, 28, and 90 days, both with and without MPW fiber (1%, 2%, and 3%). Compression tests, 3-point bending tests, and pull-out tests were used to measure the fibers' compressive strength, flexural strength, and maximum load-bearing capacity, respectively. According to the results, the compressive strength (CS) and elasticity modulus (MOE) decreased with increasing fiber content when MPW fiber was added. In the long term, the CS and MOE decrease for the LC containing 3% MPW fiber was 8% and 7%, respectively, lower than for the control concrete. At 90 days, the flexural strength of the LC with 1% MPW fiber was marginally higher than that of the control concrete, rising by 2.40%. After this initial rise, however, the flexural strength declined as the fiber concentration increased, eventually reaching an 8% reduction for LC with 3% MPW fiber.The optimum method for determining maximal load-bearing and comprehending the deformation mechanism is hence the fiber pull-out test. The microstructure study of the LC examined how the pull-out test affected the quality of bonding at fiber-matrix interfaces. The tensile and flexural strength of lightweight concrete are enhanced by MPW fiber's ability to bear significant pulling stress.

Abstract: Deformation analysis of sheet metal parts helps to map the distribution of deformation zones during pressing in problematic areas of the car bodywork. This allows to solve and prevent production problems at the press shop. The present work is focused on the optimization of the process by point pattern deposition on hot-dip galvanized metal sheets for deformation analyses. Obtained data are evaluated by GOM Argus system. Two technologies of the pattern deposition, namely electrochemical and laser are compared. Both deposition methods behave differently in the forming process and show different deformation values. The microstructure analysis done by a scanning electron microscope shows that the influence of laser setting on the material is more significant compared to electrochemical etching. Laser material shows thermal influence on the base material and the formation of micro notches. Both technologies are compared using light optical microscopy, scanning electron microscopy and electron backscattered diffraction.

Abstract: Hybrid metal matrix composites (MMCs) were prepared with AA 5754 as matrix and B₄C (fixed with 1 wt.% and average particle size as 25 μm) and Al₂O₃ reinforcements (varied from 0.5 to 2 wt. % with the interval of 0.5 and average particle size as 50 nm) using Rheo-squeeze casting process. Microstructure images were taken to observe the uniform distribution of reinforcement particles on the matrix alloy. The tensile strength for AA 5754 with 1 wt.% B₄C and 2 wt.% Al₂O₃ hybrid composite showed higher value compared to base alloy and other composites. The wt. % of Al₂O₃ in the composite is increased to 2 %, the tensile strength and compressive strength were also increased due to combined Rheo-squeeze casting. AA 5754 reinforced with 1 wt.% B₄C and 1.5 wt.% Al₂O₃ MMC indicated the Impact strength value of 30 Joules which is higher than AA 5754 matrix alloy and other compositions.

Abstract: Although many problems in aluminium matrix composites have been solved, there are still many difficulties and challenges that need to be solved. In this work, graphene reinforced aluminum matrix composites are prepared by hot isostatic pressing and vacuum sintering. The microstructures of composite powders and composites were studied by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of different ball milling parameters on the microstructures of composite powders were analyzed. The particle size of graphene coated aluminium composite powder increases with the increase of ball-to-material ratio. With the increase of milling time, graphene was gradually dispersed and coated on the aluminium powder particles, and the aluminium powder particles could be completely coated. with the increase of the speed, the large particles are extruded, sheared and the particles become smaller. The internal micro-deformation characteristics of graphene reinforced aluminium matrix composites were analyzed in detail.