Large-size Parts Research Articles

LUCEFIN 50CrMo4 (1.7228)

Abstract Lucefin 50CrMo4 is a medium-carbon, chromium-molybdenum direct hardening alloy steel that is also suitable for flame hardening, induction hardening, and nitriding. This steel is a medium hardenability steel in the 0.45 to 0.50 mean carbon content classification. In general, it is used for medium and large size parts requiring high hardness as well as high strength and good toughness. A minimum of 90% martensite in the as-quenched condition is desirable. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-877. Producer or source: Lucefin S.p.A.

VOESTALPINE AUSTRALIA 4140

Abstract Voestalpine Australia 4140 is medium-carbon, chromium-molybdenum direct hardening alloy steel that is also suitable for flame hardening, induction hardening, and nitriding. This steel is a medium hardenability steel in the 0.40 to 0.42 mean carbon content classification. In general, it is used for medium and large size parts requiring high strength and toughness. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on heat treating, machining, and joining. Filing Code: SA-873. Producer or source: voestalpine High Performance Metals.

Метод и аппаратура инфракрасного и ультразвукового термографического контроля крупногабаритных композиционных изделий сложной формы

A robotic system for combined thermal nondestructive testing of large-size parts, including data fusion, is described. The efficiency of combining results of infrared (IR) and ultrasonic IR thermographic inspection has been demonstrated on a complex-shape reference sample containing 18 surrogates of manufacture and in-service defects. The data fusion algorithms including IR image stitching in space and automated defect detection and characterization by using a neural network have demonstrated efficiency of the proposed approach in practical testing.

Thermal Plasma Spray to Protect Large-Size Parts of Friction Joints against Wear

The authors thereof have developed a technology for application of wear-resistant coatings to protect against wear. The research team tested how efficiently powdered material could be heated in a plasma jet. They studied the physical and mechanical properties of coatings by kinetic micro-indentation and tested the plasma sprays for wear resistance. Tribological laboratory tests used the roller-on-roller method. Thus, WC/Co/Cr coatings had the most stable tribological properties and were more wear-resistant, compared to other tested coatings. Cylinder liners of heavy-duty diesel engines were enhanced by this technology. The pilot batch showed promise, as it might triple effectively the service life of diesel engines.

Experimental investigation and numerical simulation of the stress and deformation behavior for selective laser sintering of PA6

The uneven temperature field caused by the local instantaneous heating of the laser generates the thermal stress during the selective laser sintering. The stress causes the deformation of parts, affecting the precision and mechanical properties. However, it’s difficult to directly measure the stress history and deformation behavior during processing through experimental methods due to its ultra-high temperature and closed cavity. In this paper, the effects of laser power and scanning speed on the stress field and deformation of polyamide 6 by selective laser sintering were systematically investigated. The results showed that as the laser power increased or the scanning speed decreased, the z-direction stress and deformation of the specimens increased. Based on the inherent strain method, the deformation behavior of large-size parts was evaluated and in good agreement with experiments, which can guarantee the accuracy of the model and predict the deformation of parts.

Effect of Heat Treatment on Structure and Properties of Martensite Stainless Steel for Ice-Class Ships Obtained by Direct Laser Deposition Method

At present, to increase competitiveness of shipyards for manufacturing of shipbuilding parts new high technologies are used. Additive production methods, including direct laser deposition (DLD) technology, which meets all the requirements of competitiveness, are increasingly being applied. Heavy-duty large-size parts such as propellers, blades, hubs and other critical parts used in shipbuilding have become possible to produce with DLD. In the process of DLD it is possible to produce parts, including shipbuilding steels used in the Arctic conditions, with the required mechanical characteristics not inferior to similar brands of materials obtained by casting or plastic deformation methods. The work is devoted to research of thermal process influence on structure and mechanical properties formation of deposited samples from steel powder 06Cr15Ni4CuMo. Features of formation of microstructure components by means of optical microscopy, X-ray structure analysis (XRD) are investigated, and also CCT diagram is constructed. Tensile and impact toughness tests have been conducted. As a result, it was found that the material obtained by the DLD method in its initial state significantly exceeds the strength characteristics of heat-treated castings of similar chemical composition, but is inferior to it in terms of plasticity and viscosity. The increase of viscosity and plasticity up to the level of cast material in the grown samples is achieved during the subsequent heat treatment, which leads to the formation of the structure of tempered martensite and reduction of its content in the two-stage tempering in the metal structure. The strength of the material is also reduced to cast metal after heat treatment.

Multi-View-Based Pose Estimation and Its Applications on Intelligent Manufacturing.

Pose estimation is a typical problem in the field of image processing, the purpose of which is to compare or fuse images acquired under different conditions. In recent years, many studies have focused on pose estimation algorithms, but so far there are still many challenges, such as efficiency, complexity and accuracy for various targets and conditions, in the field of algorithm research and practical applications. In this paper, a multi-view-based pose estimation method is proposed. This method can solve the pose estimation problem effectively for large-scale targets and achieve good performance accuracy and stability. Compared with existing methods, this method uses different views (positions and angles), each of which only observes some features of large-size parts, to estimate the six-degree-of-freedom pose of the entire large-size parts. Experimental results demonstrate that the accurate six-degree-of-freedom pose for different targets can be obtained by the proposed method which plays an important role in many actual production lines. What is more, a new visual guidance system, applied into intelligent manufacturing, is presented based on this method. The new visual guidance system has been widely used in automobile manufacturing with high accuracy and efficiency but low cost.

A method to generate AWJ cutting path for a large-size part without well-defined location characteristics

Machining composite parts is a challenging manufacturing process. Many of these composite parts are not only with very large sizes but also lack of well-defined location characteristics. And usually, these composite parts are with burrs distributed on the periphery that require trimming. An industrial robot equipped with an abrasive water jet (AWJ) has been proved to be an effective method for trimming composite parts. This article proposed a method to solve the problem of trimming large-size composite parts without well-defined location characteristics with an AWJ robot. A standard block is bound on the end effector of the AWJ robot, as a locating reference. Then, by moving the AWJ robot so that this standard block is at the proximity of selected regions, the selected regions, along with this standard block, are scanned with a portable laser scanner. With the help of the standard block, a local coordinate system is established for the point cloud generated at each region. And further, the point clouds of these several regions are constructed into an integrated point cloud system through coordinate system transformation. Therefore, without using a large batch of magnetic stickers, a point cloud system of the large-size part is obtained. Finally, by matching the point cloud system with the 3D model of the expected final product, the 3D model of the expected final product is used to generate the tool cutting path with a special 3D CAM program. With this method, trimming large-size composite parts without well-defined location characteristics becomes realistic.

Continuous Eulerian tool path strategies for wire-arc additive manufacturing of rib-web structures with machine-learning-based adaptive void filling

Rib-web structures are used for lightweight design in various applications. The most prominent cases are found in aerospace engineering, where intricate structures are produced by forging and subsequent machining or by machining from solid blocks of material. Due to the large scrap rate involved in conventional manufacturing, rib-web structures are suitable applications for additive manufacturing (AM) processes. Among the AM processes, wire-arc additive manufacturing (WAAM) is highly suitable for rib-web structures due to its high deposition rate and the potential to manufacture large-size parts. In WAAM, the welding strategy greatly influences the properties and quality of deposited parts. With an increasing number of starts and stops, the danger of uneven material build-up and welding defects increases. Unfortunately, most rib-web structures do not represent Eulerian paths, i.e. they cannot be manufactured with a continuous welding motion, in which every edge is visited only once. This study presents a novel strategy for generating optimal tool paths for WAAM of lightweight rib-web structures, mitigating the disadvantages of discontinuous welding paths such as welding defects and uneven build-up. It is shown that doubling the number of welding passes on each edge of the rib-web structure turns non-Eulerian paths into Eulerian paths, which can be welded continuously. When two or more weld beads are deposited on each edge, the vertices of the rib-web structure may suffer from underfilling. It is shown that this can be avoided by a correction strategy, which consists in manufacturing the part once, evaluating the size of voids in the junctions, and computing a correction to deposit the required amount of material into the center of the junction. While this strategy may be used if a single part is considered, it is shown that the tool path correction to be applied to arbitrary junction geometries can be represented by a neural network that is derived from an experimental database consisting of representative junction types. With this approach, paths for any rib-web geometry can be generated, which saves lead time in variant-rich production. The paths proposed in this work avoid non-welding moves and may hence outperform even single weld-bed strategies in terms of welding efficiency.

Manufacturing of Large Size and Highly Transparent Nd:YAG Ceramics by Pressure Slip-Casting and Post-Sintering by HIP: An Experimental and Simulation Study.

This study reports the fabrication of Nd:YAG (i.e., Neodymium-doped Yttrium Aluminum Garnet: Y3-xNdxAl5O12) transparent ceramics of a large size by the pressure slip-casting forming technique. Colloidal suspensions of primary oxides (i.e., Y2O3, Al2O3, Nd2O3, and SiO2 used as sintering aid) were cast under pressure through a porous membrane. Cakes with a good microstructural homogeneity and mean pore diameter of 90 nm were obtained. Modeling of the pressure slip-casting process at the millimetric to centimetric scale based on a computational fluid dynamics simulation showed good agreement with experimental results in terms of the casting kinetics (i.e., cake thickness and fluid flow as a function of time) and cake permeability. As a result, it was possible to better manage pressure casting parameters in order to obtain large size and homogeneous green parts. Finally, transparent Nd:YAG ceramics sintered by vacuum sintering, followed by post-sintering treatment by Hot Isostatic Pressing (HIP), demonstrated laser slope efficiency (51.7%) and optical-to-optical efficiency (44%) with 130 mJ of output laser energy at 1064 nm equivalent to commercial single crystals.

Автоматизированный тепловой неразрушающий контроль крупногабаритных изделий

Автоматизированный тепловой неразрушающий контроль крупногабаритных изделий

Effect of Oxide Particles on Microstructure and Mechanical Properties of the 45 Carbon Structural Steel

Striking difference in density between the oxide and the steel results in difficulty in preparing oxide dispersion strengthened steel with large size parts or materials. In this research, Al2O3 and TiO2 particles were initially milled with the 20 steel, and then the mixture was heated to a molten state to form a master alloy, which was used as a raw material for further preparation of the object steel. It was found that homogeneous distribution of the oxide particles was obtained in the mass production of the steel. Moreover, the obtained 45 carbon structural steel presents fine microstructures, together with improved mechanical properties, especially the impact ductility. This should be attributable to the transformation from the introduced micro-size oxide particles to the nano ones, which act as heterogeneous nucleants that play an important role in grain refinement and dispersion strengthening for the steel, during the remelting of the master alloy.

LUCEFIN GROUP 42CrMo4 (1.7225), 42CrMoS4 (1.7227)

Abstract Lucefin Group 42CrMo4 and 42CrMoS4 are medium-carbon, 1% chromium-molybdenum, direct hardening, alloy steels that are also suitable for flame hardening, induction hardening, and nitriding. These steels are medium hardenability steels in the 0.40 to 0.42 mean carbon content classification. In general, they are used for medium and large size parts requiring high strength and toughness. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on forming, machining, and joining. Filing Code: SA-861. Producer or source: Lucefin S.p.A.

Formability Analysis of Fiber Metal Laminates with Different Core and Skin Layers by Stamping Process

Fiber metal laminates (FMLs) are widely used in aerospace industry due to their unique high specific strength, fatigue resistance, corrosion resistance and other excellent characteristics. Thermosetting FMLs is generally used for forming large size parts and rarely used as raw material for producing small size and complex shape parts. This study attempts a methodology that stamping thermosetting FMLs to form cylinder shape parts before the curing process. The forming limit height of FMLs were analyzed by choosing different core materials, layup direction and skin layer thickness. And through the optimization of these variables, a better-quality part has been formed.

The process design of water quenching based on finite element simulation and its applications

ABSTRACT Quenching is a widely used process in heat treatment enterprises. Clean and cheap water quenching instead of high pollution and high cost of oil quenching or polymer aqueous solution quenching will become a trend in these enterprises. However, since the cracking problem of alloy steel parts induced by water quenching with high cooling rate has not been solved, the oil and polymer aqueous solution with low cooling rate are still widely used in various countries in the world. Water–air alternative timed quenching’ process and differential time grading quenching process proposed by us have been successfully applied to treat various large-size alloy steel parts in China. In this review paper, we will introduce the face issues in the design of these two kinds of processes based on finite element simulation (FES): (1) Main factor affecting accurate prediction of quenching stress; (2) The method to determine the optimizing process. Two engineering examples are selected to clarify how to solve the cracking issues of alloy steel part by FES.

Microstructure evolution of 42CrMo4 during hot forging process of hollow shafts for wind turbines

Large parts such as shafts for wind turbines are hot forged by upset and drawing. The repetitive heating, deformation, and cooling cause different metallurgical phenomena which directly influence the material behavior during and after the forming process. Particularly, while forging these large size parts, the temperature distribution does not remain uniform. This warrants a systematic study on heating and forging workpieces at variable temperature and austenitizing times. In this work, the influence of austenitizing time and temperatures on the microstructural evolution of the 42CrMo4 steel has been investigated. Samples have been austenitized and maintained at temperatures of 900°, 1000°, 1100°, and 1200 °C for 22, 66, and 200 min each and subsequently forged and quenched. The results have shown 42CrMo4 presented a complete recrystallized microstructure only when austenitized at 1200 °C for 200 min. Microhardness profiles have shown that increasing austenitizing time combined with higher temperature decreases the microhardness values in agreement with the decrease in resulting force; thereby, the related metallurgical phenomena of recovery and recrystallization cause material softening.

New Welding Joint Geometries Manufactured by Powder Bed Fusion from 316L

Abstract In metal additive manufacturing, an increasing demand for large size parts occurs. However, because of the economics of size, the manufacturing costs for parts do not increase linearly with their volumes. It is often economically unreasonable to directly produce large size components. Instead of directly building parts, technologies like hybrid building are used. To avoid extensive clamping devices for welding, additive manufacturing can be used to design new gap geometries. With these new geometries, the positions of the parts can be defined and the deformations that are due to thermal influences by the welding process can be reduced. Nevertheless, the powder bed fusion process leads to a different microstructure that needs to be taken into account for the welding process. The new microstructure leads to an extensive shrinkage during welding that exceeds the shrinkage of conventionally produced parts. To avoid the shrinkage, the weld gap design not only has to fulfill the requirements of conventional welding but it also needs to avoid the shrinkage of the parts. The resulting shrinkage of the parts is, in one way, a disadvantage, but it can also be used as an advantage for subsequent laser welding processes. If additively manufactured parts should be laser welded to get a smooth weld surface, normally post-processing must be performed to fulfill the necessary gap distance. This can be avoided by combining different welding processes. If the backside of a part is first welded by conventional welding, the resulting shrinkage will close the gap on the structured surface. If laser welding is then applied to a structured surface, it is nearly impossible to see the weld. This article will present new designs for welding joints and show how the different welding behavior can be used to improve the additively manufactured parts for hybrid welding processes.

Research and Application of Laser Ranging Method in Form and Position Tolerance of Precision Machining Products

Precision measurement of shape and position tolerance plays an important role and significance in manufacturing industry. It is an important link to measure and guarantee the quality of manufacturi ng. Especially for large-scale precision parts, the repeated use of measuring tools easily leads to measurement errors. Aiming at the problems of low detection efficiency, complex process and high cost of high precision three-coordinate measuring instrument for large-size parts, the characteristics of contact measurement and non-contact measurement for large-size parts are studied based on the characteristics of large-size parts. A measurement method combining laser ranging with reflective target is proposed, and a rotating shaft for fixing laser launcher is designed. A complete spherical coordinate measuring system is constructed, which is applied to the measurement of straightness, flatness, parallelism, verticality and height difference of large-scale precision machined parts. The corresponding measurement results are obtained in a constant greenhouse. On this basis, under the same temperature conditions, the same shape and position tolerance dimensions of the same part are measured by a three-coordinate measuring instrument. Comparing the results of measurement, it can be seen that the measurement results obtained by the two methods are the same in the range of 0.001 mm, and the measurement efficiency and cost of the laser ranging method have obvious advantages. This paper also gives the method of measuring the shape and position tolerance of large-scale precision parts.

Mechanical Characteristics and Wear Resistance of the Cladding Layers Obtained by Melting of Cored Wires with Simultaneous Vibration of Substrate

Abstract A wear proof layer was obtained by applying vibration with a frequency of 100 Hz and amplitude of 0; 70; 300 μm to the cored wire of Fe-Cr-B-C doping system during welding. It was shown that horizontal vibration affects the grinding process of boride inclusions: their average diameter reduces from 175 to 5 μm, and the amount of (FeCr)2B plastic phases increases during the redistribution of phases. Wear resistance of the metal, which was deposited using horizontal vibration with an amplitude of 300 μm, increases by 2.3-2.5 times due to wear with the fixed and unfixed abrasive material, and by 2.8 times due to wear under impact loads. For restoration and strengthening of large-size parts, it is proposed to add Al-Mg powder (Al = 47 - 53 %, Mg = 53-47% wt. %) to the CW charge to increase wear resistance of the deposited metal of the Fe-Cr-B-C system. This contributes to the dispersion of the boride inclusions, the average diameter of which decreases from 70 to 5 μm. In the structure of the deposited metal of the Fe-Cr-B-C system, inclusions of the complex alloyed nitrides are extricated with an average size less than 1.0 μm. As a result, the average value of microhardness increases from 700 to 900 HV. Wear resistance of the deposited metal increases by 1.5 times due to wear with the fixed and unfixed abrasive material, and by 2.0 times due to wear under impact loads.

Numerical Analysis of Influence of Mechanical Processing Conditions on Stress-Deformed State of Large-Size Thin-Wall Complex Parts

Многие предприятия приборостроительной, машиностроительной, авиакосмической отрасли сталкиваются с трудностями механической обработки крупногабаритных тонкостенных деталей сложной формы из алюминиевых сплавов, отвечающих за работоспособность всего изделия. К рассматриваемой группе деталей предъявляются повышенные требования по точности и качеству изготовления, к ним относятся несущие элементы конструкции летательных аппаратов, корпуса, волноводы, радиаторы. Зачастую допуск формы на поверхностях данных деталей не превышают 0,01 мм при площади поверхности 1-2 м2. Для обеспечения выпуска качественной продукции без увеличения производственного цикла и затрат на отработку технологии необходимо применение численного инженерного анализа для моделирования сложных технологических процессов. Статья содержит обоснование актуальности исследования взаимосвязи режимов механической обработки, схемы и усилия закрепления с технологическими остаточными напряжениями и деформациями детали. Представлены результаты анализа напряженно-деформированного состояния (НДС), возникающего в процессе фрезерования под воздействием силы и температуры резания, методом конечных элементов (МКЭ). На основе расчетов методом МКЭ показано, что в процессе фрезерования под действием силы резания в детали формируются сжимающие остаточные напряжения, приводящие к короблению поверхностей деталей. Разработана имитационная модель механического воздействия концевой фрезы на обрабатываемую деталь. Полученные результаты в дальнейшем планируется применить для формирования управляющих воздействий на параметры технологического процесса с целью повышения качества обработки и минимизации цикла производства деталей.