Complex Geometrical Components Research Articles

Wear and corrosion properties of low-temperature nitrocarburized 17-4PH SLM components

3D printing has demonstrated manufacturing and economic advantages in terms of customization, flexibility and rapid prototyping of precision complex geometric components. The 17-4PH precipitate hardening steel is notable for its excellent corrosion resistance. This study aims on enhancing the wear resistance of SLM-printed 17-4PH components through interstitial surface hardening. To eliminate microstructural defects introduced by the SLM process, the components were first subjected to solution heat treatment. Following this, a low-temperature nitrocarburizing (LTNC) process was applied at temperatures below 400 °C, resulting in the formation of an interstitial surface layer with an average thickness of approximately 17 μm. Optical microscopy and XRD analyses confirmed the presence of a dual-phase structure composed of expanded BCC and FCC phases within the hardened layer, with no detectable nitride/carbide precipitates. Quantitatively, the LTNC process significantly enhanced the surface microhardness of the components, increasing it to a minimum of 1000 HV0.2. The bulk microhardness also increased from 360 HV0.2 to 480 HV0.2, indicating an aging effect during the diffusion treatment. In terms of performance, LTNC substantially improved the wear resistance of the components. However, a slight reduction in corrosion resistance was observed, attributed to increased surface roughness and the presence of the dual-phase expanded structure.

Predicting the low‐cycle fatigue life of Ti‐6Al‐4V alloy using backpropagation neural network optimized by the improved dung beetle algorithm

AbstractIn this study, we propose an innovative approach that enhances the performance of the backpropagation (BP) neural network in predicting the low‐cycle fatigue life of Ti‐6Al‐4V alloy by improving the dung beetle optimization (DBO) algorithm with the maximin Latin hypercube design (MLHD) strategy. To address the challenges posed by complex geometric components under different temperature conditions, this research employs finite element simulation to expand the limited experimental dataset and utilizes these data to further guide and optimize the MLHD_DBO_BP model. Test results indicate that the proposed MLHD_DBO_BP model significantly outperforms the traditional finite element method (FEM) and other neural network models in terms of fatigue life prediction performance. This research demonstrates the effectiveness of machine learning models that combine experimental and simulation data in predicting the low‐cycle fatigue life of Ti‐6Al‐4V alloy.

Finite element analysis of the mechanical properties of sheet- and skeleton-gyroid Ti6Al4V structures produced by laser powder bed fusion

Additive manufacturing, and laser powder bed fusion (L-PBF) in particular, can produce complex geometric components with high resolution, and is very suitable for manufacturing lightweight triple periodic minimal surface (TPMS) structures to achieve lightweight. With regard to the two forms of the same structure, most of the previous studies focused on sheet-TPMS, but lacked the understanding of the difference between skeleton-TPMS and sheet-TPMS structures. In order to explore the characteristics of these two structures and provide theoretical support for the development of lightweight structure design, this paper compares the manufacturing performance and defect distribution of skeleton-gyroid (GSK) and sheet-gyroid structures (GSH). It employs high-precision finite element analysis (FEA) prediction and experimental verification to compare comprehensively the mechanical properties, failure behavior and energy absorption characteristics of the two structures. The results show that, compared to GSK, the larger specific surface area of GSH leads to more unmelted powder and draping adhesion, without affecting its higher stiffness and strength. Moreover, the more stable failure mode of GSH leads to more gentle stress platform stage and superior energy absorption performance. The results predicted by simulation are highly consistent with the experimental results. This improved understanding allows better prediction of the mechanical properties of the specimens using the Gibson–Ashby theory, which can reduce the experimental cost and time, and improve the resource consumption of TPMS structural performance research. This study can open new possibilities for the design and application of TPMS structures.

The anisotropy and friction effect in the design of 3D printed PLA parts – A case study

Additive Manufacturing, commonly known as 3D Printing, is one of the most affordable manufacturing processes for producing complex geometric components. This manufacturing process is also frequently used when it is needed to manufacture unique parts to replace degraded or damaged components and spare parts that are no longer available. In this reverse engineering process, particular attention must be given to the constitutive models of materials. The 3D printing manufacturing process usually requires a change of materials and introduces or increases the anisotropy. In addition, the complexity of part geometries and loading often requires using the finite element method to simulate their behaviour in service.Polylactic acid (PLA) is one of the materials frequently used in 3D Printing for its sustainability, affordability, and mechanical and thermal properties. In this study, a bushing of a hinged drawer support is reverse-engineered, and its in-service behaviour is simulated before it is manufactured using Tough PLA material through 3D printing. Furthermore, the effect of the anisotropy and the friction in the design is evaluated. The MSC Patran/Nastran 2021 software for the finite element analysis, the Ultimaker Cura 5.0 software and the Ultimaker S5 printer were used.

Research progress of carbon materials in the field of three-dimensional printing polymer nanocomposites

Abstract Three-dimensional (3D) printing technology is an additive manufacturing technology designed to rapidly process and manufacture complex geometrical components based on computer model design. Based on a 3D data model, materials are accumulated layer by layer through computer control, and the 3D model is finally turned into a stereoscopic object. Compared with traditional manufacturing methods, 3D printing technology has the advantages of saving man-hours, easy operation, no need for molds, and strong controllability of component geometry. With the development of this technology, according to the core materials and equipment and other elements of the printing molding technology, several types of 3D printing technologies such as fused deposition modeling, selective laser sintering, stereolithography, and solvent cast-3D printing have gradually formed. This review focuses on the principles and characteristics of several of the most representative 3D printing molding processes. And based on carbon nanomaterial (carbon fibers, graphene, and carbon nanotubes) reinforced polymer composite materials, the research progress of different 3D printing molding processes in recent years is reviewed. At the same time, the commercial application of 3D printing molding process in this field is analyzed and prospected.

Multi-objective optimization in incremental sheet forming of Ti-6Al-4V alloy using grey relational analysis method

Incremental sheet forming is a novel approach and advanced manufacturing process in industries, where it is capable of producing complex geometrical components with high accuracy. In this study, Ti-6Al-4V material used in aircraft, naval ships, spacecraft, armour plating and missiles was considered to determine the formability in the incremental sheet forming process. A 20 set of experiments were conducted considering three process variables such as tool rotational speed, step depth and feed rate on the response variables such as formed wall thickness, surface roughness, thrust force and wall angle. The process parameters are optimized using the grey relational analysis method to achieve a better quality of products. By execution multi-objective optimization using grey relational analysis, it is observed that 200 r/min tool rotational speed, 0.1 mm step depth and 2000 mm/min feed rate are optimum parameter settings.

Numerical modeling of laser powder bed fusion of metallic glasses: Prediction of crystallization

Laser powder bed fusion (L-PBF) is promising for producing metallic glasses (MGs) for its extremely high cooling rate and ability to manufacture complex geometrical components. However, the crystallization of MGs under different L-PBF parameters is not fully investigated, which has influences on the mechanical properties. In this study, we develop a multi-physics thermal-fluid flow model for the L-PBF process of MGs, run simulation cases for single tracks, and then analyze the molten pool morphology and crystallization behavior in the center and edge of the track, as well as the heat affected zone. The simulation results are validated against the experimental results in the literature and have provided deeper insight into the crystallization phenomenon observed in the experiments.

In-Situ Monitoring for Defect Identification in Nickel Alloy Complex Geometries Fabricated by L-PBF Additive Manufacturing

Published literature shows defect formation during laser powder bed fusion additive manufacturing (AM) of nickel base superalloys are sensitive to alloy chemistry, processing conditions, and geometry. In this work, ability to detect spatial distributions of defects is explored using in-situ monitoring of thermal signatures and surfaces. Simple and complex geometrical components were fabricated with CM247-LC® powder in an AM machine outfitted with optical and thermal sensors. The spatial and temporal variations of thermal signatures (peak intensity, decay, and number of gyrations), as well as, layer-by-layer optical images were analyzed. The observed thermal signatures were also verified with an analytical model for layer-wise heat transfer simulation that is sensitive to laser raster scan strategies. The cross-comparison data with reference to defects, obtained by X-ray tomography, were correlated with in-situ observations.

Powder interlayer bonding of geometrically complex Ti-6Al-4V parts

Powder interlayer bonding (PIB) is a novel joining technique, which has been developed to facilitate high-integrity repairs of aerospace components, manufactured from commonly used titanium alloys. The PIB technique utilises an interlayer between complex geometric components which are mated under pressure and a highly localised heating source. In this study, induction heating enabled bonding in an inert fusion zone by use of an oxygen-displacing shielding gas, with particular attention to the initial heating and pressure application. These early stages proved crucial to the elimination of pores and consolidation of the alloy powder, with porosity volume fraction reduced to just 0.5% after just 20 sec at the bonding force. The technique has produced high-integrity bonds in alloys such as Ti-6Al-4V, retaining approximately 90% of the alloy strength in previous studies, offering advantages over established joining methods such as tungsten inert gas (TIG) and plasma arc (PA) welding due to a more highly localised heating and fusion zone. It is believed that powder interlayer bonding can compete against these techniques, providing a more time and cost-effective repair route for net shape components manufactured from a range of alloys with minimal post-processing.

Beam generating and sound field modeling of flexible phased arrays for inspecting complex geometric components

The flexible phased array ultrasonic technology has been developed to tackle the long-term challenge of damage inspection in complex-profiled components. However, due to the influences of curved interfaces, it is sometimes difficult to control the transmission signal of the sound field, thereby creating unreliable transducer performances. This paper proposes the time delay laws for generating steering or focusing beams on curved surfaces (concave, convex, concave/convex) based on the ray acoustics theory. Then, we derive the analytic expression of the entire flexible array ultrasonic field based on the multiple line source model and the time delay laws. Finally, the acoustic pressure distribution of curved structures is simulated to verify the feasibility of the derived principles. The numerical results show that the beams can realize dynamic steering and focusing without distortions or disorientations even when the steering angle reaches 45 degrees. Furthermore, the influences of the specimen surface profile, steering angle and focusing distance on the acoustic field are also analyzed by the axial sound pressure plots. These preliminary results represent an essential step in the development of a nondestructive testing (NDT) system for inspecting components with complex surfaces.

The microstructure and mechanical properties of deposited-IN625 by laser additive manufacturing

PurposeLaser additive manufacturing (LAM) technology based on powder bed has been used to manufacture complex geometrical components. In this study, IN625 superalloys were fabricated by high-power fiber laser without cracks, bounding errors or porosity. Meanwhile, the objectives of this paper are to systemically investigate the microstructures, micro-hardness and the precipitated Laves phase of deposited-IN625 under different annealing temperatures.Design/methodology/approachThe effects of annealing temperatures on the microstructure, micro-hardness and the precipitated Laves phase were studied by optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometer (EDS), selected area electron diffraction (SAED), backscattered electron (BSE) imaging in the SEM and transmission electron microscopy (TEM), respectively. The thermal stability of the dendritic morphology about IN625 superalloys was investigated through annealing at temperatures range from 1,000°C to 1,200°C.FindingsIt is found that the microstructure of deposited-IN625 was typical dendrite structure. Besides, some Laves phase precipitated in the interdendritic region results in the segregation of niobium and molybdenum. The thermal stability indicate that the morphology of dendrite can be stable up to 1,000°C. With the annealing temperatures increasing from 1,000 to 1,200°C, the Laves phase partially dissolves into the γ-Ni matrix, and the morphology of the remaining Laves phase is changing from irregular shape to rod-like or block-like shape.Research limitations/implicationsThe heat treatment used on the IN625 superalloys is helpful for knowing the evolution of microstructures and precipitated phases thermal stability and mechanical properties.Practical implicationsDue to the different kinds of application conditions, the original microstructure of the IN625 superalloys fabricated by LAM may not be ideal. So exploring the influence of annealing treatment on IN625 superalloys can bring theory basis and guidance for actual production.Originality/valueThis study continues valuing the fabrication of IN625 by LAM. It shows the effect of annealing temperatures on the shape, size and distribution of Laves phase and the microstructures of deposited-IN625 superalloys.

Strategy for Texture Management in Metals Additive Manufacturing

Additive manufacturing (AM) technologies have long been recognized for their ability to fabricate complex geometric components directly from models conceptualized through computers, allowing for complicated designs and assemblies to be fabricated at lower costs, with shorter time to market, and improved function. Lacking behind the design complexity aspect is the ability to fully exploit AM processes for control over texture within AM components. Currently, standard heat-fill strategies utilized in AM processes result in largely columnar grain structures. Proposed in this work is a point heat source fill for the electron beam melting (EBM) process through which the texture in AM materials can be controlled. Through this point heat source strategy, the ability to form either columnar or equiaxed grain structures upon solidification through changes in the process parameters associated with the point heat source fill is demonstrated for the nickel-base superalloy, Inconel 718. Mechanically, the material is demonstrated to exhibit either anisotropic properties for the columnar-grained material fabricated through using the standard raster scan of the EBM process or isotropic properties for the equiaxed material fabricated using the point heat source fill.

Tailor Tempering and Hot-Spotting of Press Hardened Boron Steels

Hot forming processes are becoming a successful solution when complex geometrical components with high mechanical properties are desired. In fact, automotive structural components with tensile strengths higher than 1500MPa are being nowadays industrially produced. The technology is based on the forming and quenching of the sheet inside the forming tool using boron steels. Aiming at boosting the advantages of this technology, car manufacturers have started to demand structural components with different mechanical behavior areas in order to improve the impact response of the auto-motive passenger compartment: the so called tailor tempered components. The basic idea is to obtain final parts with different properties like it has been successfully done using tailored welded blanks. Although different solutions exist, one of the most common strategy is to use partially heated tooling, which influences the cooling of the sheet and consequently the local properties. At the present work, a special tooling with independent heated and cooled areas has been developed in order to evaluate the final properties achievable in the tailored tempering process. High and low conductivity alloys have been used to find the process limits and compare them to classical tool steels. Hardness values, Ultimate Tensile Stresses and microstructures are shown for different steels, tool temperatures and contact pressures. In the last part of the paper, the hot spotting results are presented. Different air gap diameters have been used to evaluate the possibility to create soft spots that will enable an easier cutting of geometrically accurate holes and a more suitable and ductile join between different components by using the spot welding.

Crystallographic texture engineering through novel melt strategies via electron beam melting: Inconel 718

Preliminary research has demonstrated the ability to utilise novel scan strategies in the electron beam melting (EBM) process to establish control of crystallographic texture within Inconel 718 deposits. Conventional EBM scan strategies and process parameters yield coarse columnar grains aligned parallel to the build direction. Through varying process parameters such as beam power, beam velocity, beam focus and scan strategy, the behaviour of the electron beam can be manipulated from a line source to a point source. The net effect of these variations is that the resulting crystallographic texture is controlled in a manner to produce either epitaxial deposits or fully equiaxed deposits. This research demonstrates the ability to change the crystallographic texture on the macroscale indicating that EBM technology can be used to create complex geometric components with both site-specific microstructures and material properties.

Thermal effects on microstructural heterogeneity of Inconel 718 materials fabricated by electron beam melting

Abstract

Influence of Tooling Material and Temperature on the Final Properties of Tailor Tempered Boron Steels

Hot forming processes are becoming a successful solution when complex geometrical components with high mechanical properties are desired. In fact, automotive structural components with tensile strengths higher than 1500MPa are being nowadays industrially produced. The technology is based on the forming and quenching of the sheet inside the forming tool using boron steels. Aiming at boosting the advantages of this technology, car manufacturers have started to demand structural components with different mechanical behavior areas in order to improve the impact response of the auto-motive passenger compartment: the so called tailor tempered components. The basic idea is to obtain final parts with different properties like it has been successfully done using tailored welded blanks. Although different solutions exist, one of the most common strategy is to use partially heated tooling, which influences the cooling of the sheet and consequently the local properties. At the present work, a special tooling with independent heated and cooled areas has been developed in order to evaluate the final properties achievable in the tailored tempering process. Furthermore, high and low conductivity alloys have been used to find the process limits. Hardness values, Ultimate Tensile Stresses and microstructures are shown for different steels, tool temperatures and contact pressures

Roadmapping Lessons from The Basque Country

Since its origins in Motorola in the 1970s (1), technology roadmapping has been adopted widely by many organizations in different sectors around the world. The underlying concept is very flexible, and roadmapping methods have been adapted to suit many different goals, supporting innovation, strategy and policy development and deployment (2). Roadmaps generally take the form of a graphical representation that provides a high-level strategic view of the topic of interest, supported by appropriate documentation. The most flexible framework comprises a multilayered time-based chart, bringing together various perspectives into a single visual diagram (Figure 1). Companies require effective, rapid and flexible (agile) methods to make strategic decisions in a world that is becoming ever more competitive. The increasing pace and complexity of technological innovation requires effective communication between commercial and technical parts of the organization. Fast-start roadmapping techniques meet these requirements; they are based on workshops that bring together the various stakeholders involved, using wall charts structured in accordance with roadmapping principles to guide discussion and capture views (3,4). Case Experience Stimulated by the fast-start roadmapping method, five roadmapping applications have been undertaken in the Basque region of Spain. The applications are diverse, as shown in the Table, next page, including the factors that characterize and differentiate each application, which resulted in the need to adapt the approach for each case. The scope, context and aims varied among the cases: * Linking technology projects with marketing objectives for a firm that manufactures and services equipment for the building sector (Case A). * Exploring and leveraging synergy opportunities to achieve more ambitious innovation goals for three companies belonging to a group that produces components for home appliances (Case B). * Aligning R&D with emerging trends in the automotive sector for a research organization that belongs to a group of component manufacturers producing complex geometric components specified by OEMs for global markets (Case C). * Identifying, specifying and evaluating new opportunities (and associated research challenges) that could exploit strengths in established technological capabilities, at both firm and research consortium levels (Cases D and E, respectively). [FIGURE 1 OMITTED] From the five cases summarized above, a number of concepts and issues relevant to strategic technology and innovation management have emerged: 1. Setting Aims and Approach A roadmap shows the navigational route from the current situation to the desired future state, with the roadmapping process following a reasoning path to produce the roadmap from available information and resources. The approach needs to be tailored to the specific application and company context. Innovation drivers (factors that stimulate the setting of an innovation goal) influence the way in which roadmapping is customized--in particular, the order in which the layers of the roadmap are tackled: * Market factors: Cases B and C, which both involved customer-focused organizations, adopted a market-pull approach where priorities relating to market needs were set before considering product requirements and how technology could be used to address them. * Technology factors: Cases D and E adopted a technology-push approach, with a mixed push-pull process for Case A (a business with a stable relationship with universities and research organizations). In all these cases strong technology development activities were in place, but there were concerns regarding commercialization. 2. Structuring the Roadmap Developing an appropriate roadmap structure requires the identification and organization of all relevant aspects that must be considered and analyzed. …

Workpiece surface integrity of Ti-6-4 heat-resistant alloy when employing different polishing methods

The use of heat-resistant titanium alloys for the manufacture of gas turbine engines components for aerospace/energy applications has become a routine exercise. However, components with complex designs specifications might pose manufacturing challenges especially when finishing processes are needed to enable their compliance with tight industrial standards for workpiece surface integrity. Information on polishing processes for such sensitive industrial applications is scarce. The paper reports on the influence of polishing methods/strategies on the quality and integrity of workpiece surfaces obtained after different polishing methods on Ti-6-4 heat-resistant alloy. The research focuses on identifying an “optimised” polishing strategy that will enable finishing a family of targeted safety critical aero-engine (TSCA-E) components, on which the simultaneous fulfillment of the following technological/quality criteria is required: (i) tool life to enable polishing of minimum of workpiece surface areas that are related with specific features of TSCA-E components; (ii) removal of pre-machining (i.e. milling) marks while obtaining required surface finish; (iii) generation of damage-free polished surfaces, i.e. high workpiece surface integrity. Two (belt; bob) polishing methods with various media/grades (Al 2O 3, SiC, polycrystalline diamond) of the abrasive materials in conjunction with three cutting media (dry; chilled air; minimum quantity of lubricant) have been tested to address the overall finishing of TSCA-E components. Although significant differences in tool life performance exist between belt and bob polishing methods, both are capable to meet the requirements of minimum workpiece surface coverage if “optimised” operating parameters are employed. When considering surface roughness criteria, Al 2O 3 belts and SiC bob tools were found appropriate. Furthermore, surfaces obtained with these tools when employing cooling media (chilled air for belt polishing and minimum quantity of lubricant (MQL) for bob polishing) showed compliance with the tight requirements of industrial standards for workpiece surface integrity (metallurgical damage and residual stresses). This proved that belt and bob polishing methods can be employed in conjunction as “hybrid” technique to enable automated overall finishing of complex geometrical components.