Key Engineering Materials Vol. 1012

Abstract: Many complex components may contain thin-walled flanges which are produced by end face turning operation. These thin-sections are likely to deform during end facing due to cutting forces resulting into form error in the final component. The current study mainly aims to understand the mechanistic cutting force components for thin-walled flange section with respect to its rigid counterparts. In order to realize the mechanistic cutting force components, advantages of both analytical and experimental approaches are exploited. First of all, process geometry variables such as uncut chip thickness, actual width of cut, instantaneous cutting speed are defined for end face turning. Based on the uncut chip thickness and actual width of cut, the effective cutting area is calculated which will be used as input for cutting force model. A separate set of machining experiments need to be conducted for finding out the values of cutting constants. Next, various cutting force components for end face turning are to be determined based on the effective cutting area and cutting constants. The variation in resultant force profile in thin-walled flange section is more with respect to rigid central core section. The force magnitude is gradually increasing in outer thin-walled flange section due to gradual reduction of workpiece deflection of the flange part whereas in central core section, force magnitude is almost constant in absence of workpiece deflection. The axial force component is more significant factor for part deformation and respective form error determination. The cutting force and feed force components are responsible for determination of power consumption. The axial force component is almost insignificant in this case.

Abstract: Microforming holds great importance due to the rising demand for miniaturized parts across diverse industries. It enables the efficient mass production of small-scale components using sheet metals. By exploring microforming processes, researchers can uncover the unique challenges and opportunities associated with manufacturing at the microscale. This research work investigates the impact of temperatures during the annealing on the mechanical properties, microstructural behaviour and formability of austenitic stainless steel 316 thin sheets. The thin sheet, with a thickness of 50µm was considered for the present analysis and were annealed at temperatures ranging from 400 to 1000°C for 30 minutes. Tensile tests were performed and mechanical properties were evaluated at various annealing temperatures. It was witnessed that as the temperature of annealing increases, the ultimate tensile strength reduces and ductility enhances. Erichsen cupping tests were conducted to assess the formability, measuring the dome height of the drawn cups. The results revealed that the as-received thin sheet exhibited poor formability. However, increasing the annealing temperature resulted in enhancing the formability, as evidenced by an increase in the dome height of the drawn cups. Furthermore, the annealing process led to an increase in grain size, which in turn inversely affected the material strength. Therefore, annealing not only enhanced formability but also influenced the microstructural characteristics of the stainless steel 316 foils. Fractography studies were done and the results show that higher annealing temperatures result in ductile fracture, which is favorable for practical applications. At lower temperatures, brittle fracture occurs with the presence of river markings. The present work helps in selecting appropriate annealing conditions for improved toughness and resistance to sudden failure in micro parts.

Abstract: Traditional sheet metal forming processes necessitate specialized tooling and costly dies to manufacture sheet metal components, leading to time-consuming and uneconomical procedures that are particularly unsuitable for batch production. However, Single Point Incremental Forming (SPIF) has emerged as a cost-effective solution for rapid prototyping, customization, and batch production. To achieve this, precise estimation of the incremental sheet forming force is essential, necessitating the design of dedicated equipment and the adaptation of machinery. This study explores the impact of several process parameters on the forces involved in SPIF to investigate their effects. Specifically, the focus is on analyzing the influence of step size, forming angle, and spindle speed on axial peak forces for Cp-Ti grade sheets. The results reveal that the maximum forming force increases with larger step downs, while a decrease in forming force is observed for smaller step sizes. Additionally, higher forming angles result in increased friction between the tool and the blank, leading to elevated forming temperatures. The evolution of forming force, which varies under different bending conditions, could serve as an indicator to prevent sheet failure. The current provides valuable insights into optimizing SPIF processes by understanding the relationship between process parameters and forming forces, facilitating more efficient and reliable production of sheet metal components.

Abstract: An artificial neural network (ANN) system was created to analyze and simulate the relationship between process parameters of dissimilar weld joints of Aluminum alloy 6061 (AA60061) and pure copper and their resulting mechanical properties. In this study, 2.2 mm thick Aluminum Alloy 6061 and 1.4 mm thick pure copper lap joints are welded using friction stir spot welding (FSSW) process. Tensile-shear tests were performed to evaluate the mechanical characteristics of the lap joints. The welding process parameters are tool speed, plunge depth, and dwell weld time. Optimum friction stir spot welding (FSSW) parameters are identified to achieve the maximum shear load for Aluminum alloy (AA 6061) and pure copper lap joints. This is accomplished at a rotational speed of 2000 rpm for a duration of 20 seconds, with a plunge depth of 0.2 mm. At 15s dwell time and 2000 rpm tool speed, the shear load increases with increasing plunge depth. The best regression neural network that has the least mean squared error of 0.10192 and coefficient of correlation of 0.85033 is the model of 5 neurons in the hidden layer of the system

Abstract: The structural requirements for power plants service environment characteristically demand for welded joints of multi-materials and hybrid structures. The excellent corrosion resistance of AISI 316 and API 5L X56; the negligible response of AISI 316 to magnetic field and the economic viability of API 5L X56 makes these alloy considerable as hybrid structure in power plants application. Also, the appropriate filler metals that will support the intended properties for the proposed service condition is critical for a quality Dissimilar metal welded joint (DMWJ). This study investigates the effect of filler metals on the microstructural and mechanical properties of DMWJ produced from carbon steel API 5L X56 and stainless steel 316L using Gas Tungsten Arc (GTA) welding techniques. The DMWJs were produced using duplex ER2209, austenitic ER308 and austenitic ER316 grade filler. Microstructural evaluation of the joints revealed macro segregation occurrence and formation of type II boundaries at the interface of API 5L X56 steel. In tension tests, the ER2209 filler metal joints showed the maximum ultimate tensile strength values compared to the welds of other filler metals. The average yield strengths of the three welded joints were higher than those of AISI 316L base metal (BM), which indicates that the yield strength of all the welded joints can satisfy the minimum requirements of engineering application for the API 5L X56/AISI 316L DMWJs. The highest hardness value of about 237.5Hv was obtained in the ER2209 filler metal weld. Keywords: AISI 316; API 5L X56; Dissimilar metal welds; GTAW; Mechanical properties; Microstructural characteristics.

Abstract: Friction stir welding (FSW) is often preferred for joining aluminium and other lightweight metals in the square butt and lap configurations. The present work focuses on studying the interfacial temperature variation along and transverse to the weld direction during friction stir lap welding (FSLW) of AA7075-T6 mounting the thermocouples on both the advancing side (AS) and retreating side (RS) of the joint during FSLW of 3 mm thick plates using two different pin lengths. The peak temperature noted at the starting, middle, and end of the weld length is consistent, thus suggesting a steady heat generation during the process. However, there is an asymmetry in temperature distribution at the AS and RS of the joint, and the temperature recorded on AS is higher than RS. The peak temperature at a location reaches after a delay of the tool passes, suggesting a variation between the leading and trailing sides. The peak temperature for the joint obtained with the 4 mm pin length is around 40-50 °C higher than the joint with 3 mm pin length.

Abstract: Corrosion poses a significant challenge in the marine industry, leading to the deterioration of equipment and structures, and resulting in substantial costs for its management and control. This comprehensive review focuses on how metal structures in marine environments, such as ships, are affected by corrosion. It explores different forms of corrosion and strategies to prevent it, particularly in the context of marine vessels. The review includes real-world examples of ships, highlights the financial impact of corrosion in the marine sector, and examines the factors contributing to its occurrence. Corrosion prevents a significant issue for marine vessels and related equipment due to the potential damage to the metal they constructed form. However, there are effective methods to mitigate this problem, such as employing corrosion-inhibiting substances and selecting appropriate materials. The susceptibility of materials to corrosion varies depending on their composition, resulting in either widespread deterioration or localized damages. By thoroughly examining the corrosion challenge within the maritime industry, this review provides insights into managing and mitigating its effects more efficiently.

Abstract: Aluminium Metal Matrix Composites (AMMCs) play a significant role in diverse industries such as automotive, aerospace, and structural sectors due to their unique characteristics, including low density, high hardness, wear-resistance, and corrosion resistance. Typically, these composite materials employ synthetic reinforcements like SiC and Al2O3, which contribute to higher production costs. However, agricultural waste materials, which are abundantly available worldwide and pose environmental and health risks, have shown potential as suitable reinforcement materials for AMMCs. This study focuses on the development of a novel aluminium metal matrix composite by incorporating Palm Kernel Shell (PKS) particles into AA 7075 in varying percentages (5wt%, 10wt%, 15wt%, 20wt%). Stir casting was employed to produce the composite samples. Mechanical and anticorrosive experiments were conducted to evaluate the resulting materials. The research findings indicate a significant enhancement in the tensile strength and hardness of the composites, along with a reduction in corrosion rates. The most favorable samples exhibited an 8.25% increase in tensile strength, a 23.9% improvement in hardness, and a remarkable 61.6% decrease in corrosion rate.

Abstract: This study investigates the effectiveness of carbon nanotubes (CNTs) in enhancing the surface hardness of mild steel through carburization. CNTs were synthesized via chemical vapor deposition at 700°C using iron nitrate and cobalt nitrate as precursors on CaCO₃ support. Acetylene was used as the carbon source and nitrogen as the inert gas. The as-synthesized CNTs were purified using a one-step nitric acid treatment. Characterization by SEM, TGA, and FTIR revealed CNT diameters of 42-52 nm and improved thermal stability after purification, with TGA showing mass losses of 78% for as-synthesized CNTs and 85% for purified CNTs. Low carbon steel (AISI 1018) samples were carburized with as-synthesized and purified CNTs at austenitic temperatures of 750°C and 800°C for period ranging from 10 to 50 minutes. The carburizing process involved heating at 10°C/minute, followed by a defined number of boost and diffusion steps. Surface hardness was evaluated using a Vickers FM 700 micro-hardness tester, and microstructure was checked with an Olympus SC50 optical microscope. Results show that the use of purified CNTs in the carburization displayed the highest surface hardness of 191.64 ± 4.16 GPa at 800°C for 50 minutes, representing a 32% increase over the untreated substrate (145.188 ± 2.66 GPa). As-synthesized CNTs yielded a hardness value of 177.88 ± 2.35 GPa under the same conditions. At 750°C, the percentage increase in hardness for as-synthesized CNTs and purified CNTs were 10.04% and 15.77%, respectively, compared to the untreated substrate. Higher carburization temperature and longer treatment time consistently increased the surface hardness. The use of purified CNTs resulted in an increase of 6.37% hardness when compared to that of the as-synthesized CNTs at 750°C. Microstructural changes in the steel samples confirmed improved surface hardness with both purified and unpurified CNTs, with purified CNTs showing superior performance. This study therefore provides a platform for the use of CNTs for enhancing surface hardness of steel for various industrial applications requiring enhanced mechanical properties and wear resistance in low carbon steels.