Iron-based Powder Research Articles

The Influence of Surface Extrusion Densification on the Microstructure and Mechanical Properties of Iron-Based Powder Metallurgy Gears

The Influence of Surface Extrusion Densification on the Microstructure and Mechanical Properties of Iron-Based Powder Metallurgy Gears

Finite Element Analysis of Densification Process in High Velocity Compaction of Iron-Based Powder.

A finite element model based on elastic-plastic theory was conducted to study the densification process of iron-based powder metallurgy during high velocity compaction (HVC). The densification process of HVC at different heights was simulated using MSC Marc 2020 software with the Shima-Oyane model, and compared with the experimental results. The numerical simulation results were consistent with the experimental results, proving the reliability of the finite element model. Through finite element analysis and theoretical calculation, the high-speed impact molding process of metal powder was analyzed, and the optimal empirical compaction equation for iron-based powder high-speed impact molding was obtained. At the same time, the influence of impact velocity and impact energy on the relative density distribution cloud map and numerical values of the compact was analyzed.

Prediction of the microstructure of cold-compacted Astaloy 85Mo with deep generative models

In powder metallurgy, iron-based powders are compacted to so-called green bodies, which undergo a subsequent sintering process. The microstructure of the green bodies affects the sintering process and the resulting properties of the produced component. Assessing the microstructure experimentally is time consuming and costly, while simulation approaches rely on simplifications that significantly affect relevant microstructural information. This work investigates the suitability of deep generative models to synthetically generate realistic micrographs of green bodies as an alternative to experiments and simulations. For that purpose experiments comparing Generative Adversarial Neural Networks and Variational Autoencoders were conducted. The two deep learning frameworks were used to train models which produce synthetic micrographs in dependence of two parameters, namely powder particle size and green body porosity. The data utilized to train and evaluate the models was acquired from compacted water-atomized Astaloy 85Mo via scanning electron microscopy. Besides visual inspection, the trained models were evaluated via quantitative metrics. Distributions of relevant microstructural parameters such as pore perimeter or minimum and maximum pore feret diameter of the synthetically generated micrographs were compared to those of experimentally acquired micrographs. The results indicate that Generative Adversarial Networks represent a promising approach to train models, which produce synthetic micrographs that capture relevant properties of green body micrographs in dependence of given parameters such as powder particle size. In contrast, the Variational Autoencoders trained for this study did not capture microstructural properties well.

Braking Performance of Fe-Based and Cu-Based Powder Metallurgy Pads Paired with C/C-SiC Disk on Full-Scale Dynamometer

In this study, the friction performance of copper-based (Cu-PM) and iron-based (Fe-PM) powder metallurgy pads was systematically compared and analyzed by performing a braking test paired with a C/C-SiC disk on a full-scale flywheel brake dynamometer, including coefficient of friction (COF), wear rate (Wr), and worn surface under dry and wet tests. The test procedure simulated the braking conditions on high-speed trains with initial brake speeds (IBS) from 50 km/h to 200 km/h, as well as under various brake clamping forces (FB). During dry tests, both pads exhibited high levels of COF. The mean value of average COF (µm) for the Cu-PM pad was 0.371, which was slightly higher than that of 0.358 from the Fe-PM pad. The stability of µm over the IBS ranged from 68% to 82% for Cu-PM pads under different FB, while it was from 82% to 85% for Fe-PM pads. However, during the wet tests, the mean value of µm dropped to 0.207 for Cu-PM pads, and with the minimum µm of 0.062; whereas, they were 0.344 and 0.188 for Fe-PM pads, respectively, showing a significant difference in the friction performance between the two pads. Additionally, the Wr of the Cu-PM pad was 0.110 cm3/MJ during dry tests, which was 17.3% lower than that of 0.133 cm3/MJ observed for the Fe-PM pad. After the brake test with the Cu-PM pad, the friction film primarily covered the Si/SiC-rich region of the disk, effectively inhibiting the plowing of SiC hard asperities onto the pad surface. However, the friction film predominantly covered the fiber-rich region of the disk after the test with the Fe-PM pad, and the exposure of hard Si/SiC-rich asperities would continuously plow the pad during braking and resulted in furrows on the surface of the Fe-PM pad. In terms of wear mechanisms, adhesion wear was the primary mechanism on the contact surfaces of the Cu-PM pad and the C/C-SiC disk, while abrasion dominated the interaction between the Fe-PM pad and the C/C-SiC disk. This study provides valuable insights for the application of C/C-SiC brake disks on trains.

The Effect of Epoxy Resin on the Infiltration of Porous Metal Parts Formed through Laser Powder Bed Fusion

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution.

Influence introducing various plasticizers into an initial charge on the structure and properties of iron-based powder materials alloyed with copper

Influence introducing various plasticizers into an initial charge on the structure and properties of iron-based powder materials alloyed with copper

Effect of Different Content of CeO2 on the Evaluation of Micro-Structure and Wear Data of Boride Layer of Iron Based Powder Metallurgy Materials

Iron base powder metallurgy sample was borided with different content of CeO2 (0 wt.%, 2 wt.%, 4 wt.%) at 950 °C for 5 h by using solid powder boriding method. The wear tests were carried out on the friction and wear tester model MPX-3G. Scanning electron microscope (SEM), X-ray diffraction analysis, Rockwell hardness tester model Huayin HR-150A and three-dimensional non-contact tester model ST400 were used in the evaluation of micro-structure and wear data. The results show that samples with best performance in the evaluation of micro-structure and wear tests were borided with 2% CeO2.

Study of the Plasticizer Effect on Technological Properties of Iron-Based Powder Materials Alloyed with Copper

Study of the Plasticizer Effect on Technological Properties of Iron-Based Powder Materials Alloyed with Copper

Microstructure and Properties of FeAlC-x(WC-Co) Composite Coating Prepared through Plasma Transfer Arc Cladding

Tungsten carbide (WC) is widely used in wear-resistant parts due to its excellent wear resistance. Iron-based alloys are used in the repair and remanufacturing of engine components due to their good compatibility with iron-based workpieces. In order to enhance the wear resistance of engine components in service under abrasive conditions, composite coatings have been prepared for cast iron engine components by adding WC-Co to iron-based powders. This study investigates the microstructure and wear properties of composite coatings of iron-based alloys reinforced with different contents of WC particles. The composite coatings mainly contained γ-Fe, α-Fe, WC and Fe3W3C. With the addition of the WC-Co strengthening phase, the average hardness of the FeAlC-x(WC-Co) composite coatings increases from 524 HV0.2 to 814 HV0.2. Wear test results showed that when the WC addition was 20%, it had the lowest frictional coefficient of 0.5 and the lowest wear mass loss of 1.3 mg. Compared to the original Fe-based alloy coatings, the WC particle-reinforced FeAlC composite coatings display improved wear resistance on a reduced friction basis, mainly benefiting from the high wear resistance of the graphite solid lubrication phase and carbides in the cladding.

ПОВЫШЕНИЕ ИЗНОСОСТОЙКОСТИ КОМПОЗИЦИОННОГО ПОКРЫТИЯ НА ОСНОВЕ ЖЕЛЕЗА ПРИ ВОССТАНОВЛЕНИИ СПЕЦИАЛЬНОГО ОБОРУДОВАНИЯ

The paper presents the results of determining rational composition of composite material based on PRX11G4SR powder with fraction of 40–64 microns with addition of titanium carbide filler (TiC) for plasma spraying coatings, providing maximum microhardness and wear resistance. For this purpose, a multivariate experiment on the central composite rototable plan was designed and implemented. The following independent variables were selected: filler size (30–70 microns) and filler concentration (10–30 %). Adhesion strength of resulting coating to base of the samples was taken as response function. The study analyzed morphology and chemical composition of the obtained coating from iron-based powder and titanium carbide particles. It outlined aspects that explain reasons for improving resulting coating microhardness during plasma spraying.

Process of Sintering Iron-Based Powder Materials Alloyed with Copper with Introduction of Various Plasticizers Into an Initial Charge

Process of Sintering Iron-Based Powder Materials Alloyed with Copper with Introduction of Various Plasticizers Into an Initial Charge

Effects of copper infiltrant amount and infiltration method on mechanical properties of sintered steel

In this paper, the effects of copper infiltrant amount and copper infiltration method on the mechanical properties of Fe-Cu-C-based sintered steel were investigated. The results indicate that the density, tensile strength, impact energy, and hardness of the sintered steel increase with higher copper infiltration. The optimal mechanical properties were achieved when the copper infiltrant amount reached 15%, resulting in a surface hardness of HRC31, an impact energy of 31.34 J, and an ultimate tensile strength of 759 MPa. Furthermore, different copper infiltration methods affected the material’s mechanical properties. When the copper infiltrant amount was 12.5%, the impact energy of the sintered steel sample was 15.41% higher using the bottom copper infiltration process (30.19 J) compared to the top copper infiltration process (26.16 J). These findings provide valuable insights for enhancing the mechanical properties of iron-based powder metallurgy sintered steel with copper infiltration.

Retracted: Construction and Performance Research of Reinforced Iron-Based Powder Metallurgy Materials Based on Phyllanthin as Drug Transport Carriers

Retracted: Construction and Performance Research of Reinforced Iron-Based Powder Metallurgy Materials Based on Phyllanthin as Drug Transport Carriers

Exploitation of IR statistical results as a guidance for the multi-technique study of synthetic and natural iron-based pigments

Ochres are natural deposits particularly enriched in iron oxides and hydroxides giving them their typical colours spanning from bright red to yellow or brown. For this reason, they have been widely exploited over millennia for artistic purposes, becoming among the most known pigments.A series of 16 iron-based powder pigments including both commercial and natural ochres was investigated. Specifically, natural materials came from the Røros (Norway) district, where they were historically extensively used for painting the wooden houses’ facades.The set of samples was studied by applying a multi-analytical approach involving colorimetry, X-ray fluorescence, infrared spectroscopy in multiple spectral ranges and configurations, Raman spectroscopy, and X-ray diffraction. The potentiality of coupling infrared spectroscopy with Principal Component Analysis (PCA) in characterising and discriminating iron-based pigments represents an innovative approach to guide the interpretation of results obtained by applying a variety of analytical techniques, thanks to the identified clusters. This allowed, in turn, for depicting an extremely consistent description of the samples and specifically of those used in the conservation intervention of the UNESCO World Heritage site of Røros (Norway) and whose composition has never been studied before.

Hardenability of PM Steel Alloyed Using Tailored Master Alloys

Abstract The ferrous powder metallurgy industry is facing major upheavals currently, which, however, also offer opportunities. New materials and concepts, made possible by tailored design, are a way to prepare for new challenges. Alloying of PM steel through the master alloy route is a concept that combines efficient usage of alloying elements, also of such with high oxygen affinity, with accelerated homogenization via liquid phase sintering. Thus, improved properties can be attained while maintaining dimensional precision, which makes the PM route more attractive. In the present study, different master alloys containing Fe, Si, C, Cr and / or Mn have been admixed to plain iron base powder, the mixes then being consolidated by pressing and sintering. The materials thus produced are compared to two commercial sinter hardening PM steel grades in terms of hardenability. CCT diagrams are presented for all materials, and hardness data from quenching dilatometer experiments are compared to the hardness values achieved by sinter hardening in the lab furnace as well as by a classical quench-and-temper treatment.

Управление эксплуатационными свойствами порошковых материалов для повышения коррозионной стойкости и износостойкости деталей

Introduction. One of the vibration methods for processing loose finely dispersed mineral raw materials is the sepIntroduction. The quality of powder materials made of rare metals is ensured by chemical-thermal treatment, including diffusion chromosilidation. Chemical and thermal treatment of products intensifies the process of diffusion saturation, reduces the processing time and allows the use of products in aggressive and abrasive environments. Methods and materials of research. Systematization, generalization and analysis of theoretical, laboratory and experimental studies, the basis of which is the modeling of processes. Research results. It was found that when using low-alloyed powder, higher strength and viscosity indices of chromosilicated materials were obtained. It is determined that the mechanical properties of powders processed from molten salts are higher than those of materials from powder filling. It is shown that the treatment increases the corrosion resistance of iron-based powders with an established corrosion rate less than the initial one. Discussion of research results. The rapid formation of an oxide film that protects the metal from corrosion is facilitated by quenching and normalization. Porous chromosilicated layers are destroyed and impair the ability of the material to resist corrosion destruction. The operational properties of chromosilicated powders obtained by hot stamping methods increase when using rational parameters of the technological process in an optimal mode. Conclusion. The article contains new proposals for managing the properties of materials to increase corrosion resistance and wear resistance of children. Conclusions on the article. New developments can be recommended for implementation in the production of rare metals and products made from them. Suggestions. The results of the research can be used both in the modernization of production and in the training of specialists in this field.

Microstructure and elemental analysis of iron-based powder composite materials

This paper studies the kinetics of structure formation of an iron-bronze composite containing solid lubricants. Depending on the compacting pressure and sintering temperature, binary and complex phases are detected in the iron-bronze structure. The presence of solid lubricants in the composition of the composite material significantly reduces interaction of the liquid (bronze) and solid (iron) phases during sintering. Talc and graphite, which are heat–resistant at a sintering temperature of 850 – 1150 °C, were used as solid lubricants. The presence of talc, located on the surface of compressed particles of iron, copper, tin and graphite, significantly reduces the effect of their interaction. At the same time, the micro-talc particles envelop them, and its thermal stability retains this state up to high temperatures (approximately 900 °C). It was established that there is no perlite in the microstructure of iron-bronze sintered at a temperature of 850 °C. This can be explained by the talc adsorbing ability on the surface of iron particles which prevents diffusion of carbon into the iron crystal lattice. An increase in the sintering temperature up to 1000 °C leads to the formation of perlite in the iron-bronze structure, while the amount of perlite predominates over ferrite. This indicates the partial burnout of talc from the surface of iron particles and the opening of diffusion paths to carbon. At a sintering temperature of 1150 °C, perlite and a grid of light inclusions are formed in the microstructure of the iron-bronze samples. According to the results of electron microprobe analysis, the light inclusions are solid solutions of variable compositions such as Fe – Cu – Sn, Cu – Fe – Sn, Cu – Sn – Fe. In order to confirm these assumptions, a phase X-ray diffraction analysis was performed. Diffraction patterns of these samples are represented by reflections of iron and copper crystals. The absence of diffraction effects (characteristic of tin crystals) is conditioned by tin solubility in the copper lattice. This is due to the low melting point of tin (232 °C) and its ionic radius, which allows isomorphically replacing of copper and iron ions with tin ions (their difference is less than 15 %).

Study on the Influence of Warm Die Compaction Behavior on the Mechanical Properties of Iron-Based Powder Materials

Study on the Influence of Warm Die Compaction Behavior on the Mechanical Properties of Iron-Based Powder Materials

Determination of porosity functions in the pressure treatment of iron-based powder materials in agricultural engineering

One of the most effective ways to obtain products with the required performance characteristics is the cold plastic deformation of porous workpieces. The relevance of the subject under study is due to the need to increase the reliability of the stress-strain state assessment during the plastic processing of porous workpieces by clarifying the porosity functions. The purpose of the study is to develop a method for describing the mechanical characteristics of porous bodies by single functions, the nature of which is determined by the properties of the base material and does not depend on the initial porosity. Analytical, numerical, experimental, and computational methods using modern specialised software systems were used to examine the processes of plastic deformation. The study presents a method for describing the mechanical characteristics of porous bodies with single functions. A set of interrelated methods and techniques is based on the basic provisions of the mechanics of plastic deformation of porous bodies and allows obtaining reliable porosity functions for this material, by clarifying theoretical dependencies by experimental studies. Therewith, experimental data were obtained in experiments on axisymmetric upsetting of cylindrical samples without friction at the ends. Based on the conducted theoretical studies, porosity functions for iron-based materials are obtained. Samples of five different initial porosities were used for the study. As a result of processing experimental data, final expressions for the porosity functions of the iron-based powder workpiece material are obtained. The study also presents a method for calculating the accumulated deformation of the base material. Flow curves for iron-based powder materials are plotted. The obtained results will allow formulating the practical recommendations for the development of technological processes for the plastic processing of powder materials by pressure to obtain products with specified physical and mechanical properties

Influence of powder size on the moldability and sintered properties of irregular iron-based feedstock used in low-pressure powder injection molding

Initially used for shaping irregular ceramic powders, manufacturing metallic parts via low-pressure powder injection molding (LPIM) from irregular powders has received very little attention. This study investigates the processability of irregular powders for fabricating high-density and low-cost metallic parts using the LPIM process. Three irregular iron-based powder lots were mixed with a low-viscosity binder, injected, debound, and sintered to evaluate their molding and sintering performances via viscosity measurements, real-scale injections, metallographic analysis, and tensile tests. The results revealed that feedstocks formulated from fine and coarse powders exhibit good moldability, predicted by their moldability indexes and validated by spiral flow distances. Furthermore, the feedstock formulated with the finer powder (i.e., 1250 mesh providing a powder particle size <10 μm) produced a homogeneous microstructure along with a low content of oxygen impurities, leading to the highest sintered relative density of ∼90%, an ultimate tensile strength of ∼225 MPa, and an elongation at break of ∼24%. These results confirm that the cost-effective irregular iron powders present a promising alternative to fabricating metallic parts via low-pressure powder injection molding compared to their relatively high-cost spherical powder counterparts (i.e., carbonyl iron powder).