Maraging Steel Powder Research Articles

Особенности применения электродов-инструментов, изготовленных аддитивными технологиями, при электроэрозионной обработке изделий

Introduction. The paper presents the results of a study of the use of a tool electrode (TE), manufactured by selective laser alloying from MS1 maraging steel powder for copy-piercing electrical discharge machining (EDM). Purpose of the work: experimental study of the features of the use of additively manufactured TE in the EDM of critical products. Research methods. The specimens were prepared using a ReaLizer SLM 50 system. The starting material was spherical MS1 powder with an average particle size of 30 μm. To test the modes and select a TE sample with the least number of surface defects, four manufacturing modes were tested, and the best TE sample was selected for further research. The EDM was carried out on EMT Smart CNC equipment in a dielectric oil environment. The specimens were installed in a clamp with straight polarity and were used as TE; a 0.12C-18Сr-10Ni-Тi steel plate served as the workpiece electrode. The study was conducted using a factorial experiment (type 23) with a central design. The input data of the factorial experiment is the current I (A), voltage U (W), pulse on time Ton (μs). The output parameters were the roughness parameter Ra and tool electrode wear γ. The roughness parameter Ra was measured using a Mahr Perthometer S2. Results and discussion. TE samples were made from MS1 powder using the SLS method; the highest quality TE sample No. 4 was selected for EDM. Empirical equations are obtained that describe the relationship between the roughness parameter Ra and tool electrode wear γ, depending on the EDM modes. At the minimum mode with a current I = 4 A and a voltage U = 50 V, the tool electrode wear is γ = 0.0063875 g. The maximum tool electrode wear is γ = 0.13938 g with a current I = 8 A and a voltage U = 50 V. It is established that at a constant pulse on time Ton = 75 μs, the smallest roughness Ra = 2.83 μm is obtained at a current of I = 4 A and a voltage U = 100 V, and the maximum roughness is Ra = 4.1568 μm at I = 8 A and U = 100 V.

Cavitation resistance of laser-sintered MS1 steel

This study focuses on the determination of cavitation rate for samples produced by Direct Metal Laser Sintering (DMLS) of MS1 maraging steel powder without any post-processing thermal or mechanical treatment (as-built). The test samples, fabricated using an EOSINT M280 machine in a nitrogen atmosphere, were evaluated for their cavitation resistance using the ultrasonic vibration method as proposed by the ASTM G32 standard. Surface characterization to determine the duration of the experiment, as well as during and after the experiment to analyze changes in surface characteristics, was conducted using Scanning Electron Microscopy (SEM). Additionally, chemical analysis was performed using the Energy Dispersive X-ray Spectroscopy (EDS) method before and after the experiment to identify any changes and locations of significant surface damage. The mass loss of the samples over time was measured to calculate the cavitation rate. The goal of this research was to explore the potential applications of laser-sintered MS1 steel powder for manufacturing machine components and parts that are subject to cavitation erosion, due to the numerous benefits of additive manufacturing over traditional conventional technologies.

Maraging steel powder alteration caused by laser powder bed fusion printing process

Metallic additive manufacturing (AM) technologies have recently drawn a lot of interest, notably in the aerospace, automotive, and biomedical fields, as they allow a great degree of design flexibility, perform well mechanically, and reduce material waste. As long as the unfused powder is sieved and recycled for the next print, AM is a green and clean process. However, the recycled powder is prone to several modifications during the course of printing that may affect the mechanical properties of finished components. The study examines the phenomenon of powder degradation caused by laser powder bed fusion printing process and the reuse of the powder. Maraging steel was chosen because there are very few studies on the alteration of this type of powder. The effects of part location, distance between parts and lattice structure on powder characteristics were investigated. Results showed that powder particles were not uniformly distributed over the powder bed, coarsening toward the collecting bin. Nevertheless, the gas filtration system that transports spatters and fumes had no noticeable effect on the powder bed particle-size distribution (PSD). Analyses of the powder spread over the build plate revealed that the PSD shifted toward larger particles with a considerable drop in the percentage of fine particles as the spacing between printed parts was decreased. Printing lattice structures had a substantial impact on the PSD of the powder bed. The size of the particles increased remarkably as the lattice cell became tighter, while the powder morphology showed a huge amount of spatters, aggregates, “clip-clap,” elongated particles, broken particles, shattered, and deformed particles. Taken together, the study showed that the PSD of the powder became coarser and the particle morphology was altered as the number of reuses increased.

Influence of scanning speed on the microstructure, nanoindentation characteristics and tribological behavior of novel maraging steel coatings by laser cladding

This paper utilized a novel high-Mo maraging steel powder to prepare maraging steel coatings through laser cladding. The study investigated how scanning speed affects the microstructure, phase formation, nanoindentation properties, and wear properties of the resulting laser-clad maraging steel coatings. The experimental results reveal that the maraging steel coating consists of martensite and austenite phases. Moreover, diffraction peaks of Fe2Mo phase were observed at low scanning speeds. As the scanning speed increases, there is a gradual reduction in the austenite content, accompanied by a decrease in the Fe2Mo phase content. Moreover, both martensite and austenite exhibit an increase in lattice distortion. EBSD analysis demonstrates a reduce in grain size as the scanning speed increases, accompanied by the emergence of LAGBs and an increase in dislocation density, as indicated by the rising KAM value. TEM analysis confirms the presence of a Mo-rich precipitated phase, characterized by a dense hexagonal structure consisting of the Fe2Mo intermetallic compound. The Fe2Mo phase displays high hardness, thereby significantly enhancing the second precipitation strengthening effect of the coating. The nanoindentation characteristics of the S2 coating are exceptional, displaying remarkable values for nanohardness, HU, H/E ratio, and H3/E2 ratio. Specifically, the S2 coating exhibits a nanohardness of 4.843 ± 0.104 GPa, accompanied by an HU value of 0.2073 GPa. Additionally, the H/E ratio and H3/E2 ratio are reported as 0.0214 and 0.002218, respectively. Demonstrates excellent mechanical properties of S2 coating. Furthermore, the S2 coating demonstrates outstanding performance in terms of wear resistance and deformation resistance, exhibiting the lowest friction coefficient and specific wear rate, measuring at 0.438 and 1.381 × 10−5 mm3/N•m, respectively. The observed wear mechanisms in the S2 coating include adhesive wear, abrasive wear and oxidative wear. Notably, lower scanning speeds promote the precipitation of Fe2Mo particles, which play a supportive role in the wear process by weakening the tendency of oxidative wear. Overall, the remarkable properties exhibited by the S2 coating, such as nanohardness, wear resistance, and deformation resistance, position it as a promising candidate for various technological applications.

Influence of Oxygen Concentration in Building Environment and Oxidation Extent of Maraging Steel on Spatter Generation Behavior in Powder Bed Fusion

This study investigated the influence of oxygen concentration in the building environment and the degree of oxidation of maraging steel powder on spatter generation behavior during powder bed fusion (PBF) process. The powders were oxidized at various heat treatment temperatures, and their degree of oxidation was evaluated using Auger electron spectroscopy. The spatter generation behavior of the powders at oxygen concentrations of 1.0×102 ppm (99.99% purity) to 5.0×104 ppm (95% purity) in the building atmosphere was then investigated. The results indicated that the presence of oxygen in the building environment had a greater effect on spatter generation than the oxide film on the maraging steel powder. The oxygen concentration affected the velocity and angle of spatter particles. At an oxygen concentration of 5.0×104 ppm, the number of spatter particles was 2.5 times greater than that of 1.0×102 ppm. A higher oxygen concentration resulted in an increase in the number of fume particles adhering to the spatter surface, reducing its reusability. The oxide film on the powder did not significantly affect the vapor jet behavior, but it altered the powder’s flowability, impacting the spatter generation. To decrease spatter generation and obtain a high-quality spatter surface, it is recommended that the oxygen concentration in the building environment should be maintained at 1.0×102 ppm.

Study on Laser Scan Strategy for Correcting Anisotropic Residual Stress Distribution and Reducing Warpage in Structures Fabricated by PBF-LB/M

Metal-based powder bed fusion with a laser beam (PBF-LB/M) can be applied to fabricate high-accuracy structures compared with other metal additive manufacturing (AM) methods. The rapid solidification of metal powder formed by laser irradiation introduces heterogeneous residual stress, which causes deformation and cracking of the structure. This, in turn, results in the deterioration of quality. In this study, the influence of the laser scan strategy on the residual stress distribution and warpage of the structure was investigated. Using maraging steel powder with an average particle size of 32.5 μm, the structures were constructed using several laser scan strategies at a wavelength of 1070 nm. The residual stress distributions on the surface of the structures were measured by the cosα method by applying X-ray diffraction (XRD). In addition, the warpage of the reverse side of the substrate as a foundation of the structure was measured by a stylus-type surface roughness measuring instrument. The results clarified that the structures constructed by unidirectional scan directions had a tensile residual stress that was generated parallel to the laser scan direction. Meanwhile, the compressive residual stress was generated perpendicular to the laser scan direction. The large warpage was aligned with the laser scan direction and tensile residual stress. When the laser scan direction was rotated by 90° for each layer, the residual stress distribution was generated with a cruciform shape. It was indicated that this residual distribution was caused by a laser scan on the top surface and a lower layer. The anisotropic residual stress distribution and reduction of warpage could be corrected by rotating the laser scan direction by 15° in each layer.

Maraging steel powder recycling effect on the tensile and fatigue behavior of parts produced through the laser powder bed fusion (L-PBF) process

Additive manufacturing (AM) has advanced the manufacturing industry and has been employed in a wide range of industrial applications, including aerospace, automotive, medical, and die-casting equipment. To ensure the cost-effectiveness of the AM process, unfused powder must be recycled even if its characteristics may change after each cycle, making essential the validation of powder quality and component mechanical performances. Despite the research published to date, predicting the mechanical performance of printed parts issued from reused powder remains challenging since it is dependent on many AM process variables. Until now, no research has looked at the impact of powder recycling on the fatigue behavior of maraging steel components. This study investigates the impact of maraging steel powder reuse on powder characteristics, as well as on the tensile and fatigue properties of printed components. Our results indicate that the powder particle size distribution increased after eight powder reuses, particle morphology showed the presence of aggregates, broken particles, and shattered and deformed particles, while powder apparent density remained constant. Powder reusing had no significant impact on the surface roughness of as-built specimens. Although there was a slight decrease in mechanical properties over reuse cycles, tensile and fatigue performance remained globally stable, while the standard deviation of fatigue stress became narrower after eight cycles. Finally, fractography revealed that the fatigue fracture surfaces of components manufactured from an eight-time recycled powder have more fusion defects and carbon inclusions than the parts made from virgin powder.

Effects of Laser-Deposited Maraging Steel on L-PBF 316L Component

The capabilities of additive manufacturing (AM) techniques have been extensively examined in the literature. However, scientific gaps persist on the feasibility of realizing a coated component manufactured by using various materials processed by combining different AM processes. From this perspective, this study focuses on the manufacturing of a directed energy deposition (DED) coating by using 18Ni (300) maraging steel powder on AISI 316L components realized by laser-powder bed fusion (L-PBF), in order to assess the production of components with high geometrical complexity combined with high mechanical surface properties in selected areas. The quality of the manufactured coatings was assessed in-process through the implementation of an optical monitoring system and real-time image processing. In addition, an in-depth metallurgical analysis (microstructural and chemical) of the interface between the DED coating and the L-PBF component was carried out. Finally, hardness tests were performed on both the as-deposited and heat-treated coatings to confirm the high mechanical performance of the final component surface. The results revealed the potential of producing cost-effective and geometrically complex parts, such as molds or tools with internal cooling channels, that implement mechanically high-performance surfaces.

INVESTIGATING THE PROCESSES OF HOT EXTRUSION AND HEAT TREATMENT OF POROUS PRESSED METAL MADE FROM MARTENSITE AGING STEEL POWDERS OF THE ПС-H18K10M5Re TRADE

The creation of powder composite materials with high functional properties, such as maraging steel powders resistant to brittle degradation at negative temperatures, is one of the primary trends of modern material science. These steels are well machined by cutting, easily deformed and subject to heat treatment. The processes of sintering, hot extrusion, heat treatment, and structuring of porous compacts pressed from the maraging PS-H18K10M5Re steel powder obtained by synthesizing complex oxides have been studied. As a result of the research, a technology has been developed for obtaining products from maraging steel powder, including the processes of pressing porous steel powder, sintering compacts, hot extrusion and heat treatment. It is shown that the resulting powder steels are not inferior to the standard ones in terms of their physical, mechanical and technological properties, and in some cases even surpass them.

Maraging Steel Powder Alteration Caused by 3D Printing Process and Powder Recycling

Maraging Steel Powder Alteration Caused by 3D Printing Process and Powder Recycling

A Simple Method of Reducing Coolant Leakage for Direct Metal Printed Injection Mold with Conformal Cooling Channels Using General Process Parameters and Heat Treatment.

Direct metal printing is a promising technique for manufacturing injection molds with complex conformal cooling channels from maraging steel powder, which is widely applied in automotive or aerospace industries. However, two major disadvantages of direct metal printing are the narrow process window and length of time consumed. The fabrication of high-density injection molds is frequently applied to prevent coolant leakage during the cooling stage. In this study, we propose a simple method of reducing coolant leakage for a direct-metal-printed injection mold with conformal cooling channels by combining injection mold fabrication with general process parameters, as well as solution and aging treatment (SAT). This study comprehensively investigates the microstructural evolution of the injection mold after SAT using field-emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. We found that the surface hardness of the injection mold was enhanced from HV 189 to HV 546 as the Ni-Mo precipitates increased from 12.8 to 18.5%. The size of the pores was reduced significantly due to iron oxide precipitates because the relative density of the injection mold increased from 99.18 to 99.72%. The total production time of the wax injection mold without coolant leakage during the cooling stage was only 62% that of the production time of the wax injection mold fabricated with high-density process parameters. A significant savings of up to 46% of the production cost of the injection mold was obtained.

Towards controlling intrinsic heat treatment of maraging steel during laser directed energy deposition

The intrinsic heat treatment (IHT) during laser directed energy deposition (L-DED) of a maraging steel powder was investigated. The thermal history of each layer during the building process was simulated to evaluate the effect of the interlayer pause on the maximum and minimum temperatures experienced by the material. The minimum temperature decreases with the interlayer pause, enhancing the austenite to martensite transformation needed to trigger the intermetallic precipitation during the deposition of the subsequent layers. Specimens were then produced with different interlayer pauses, and the hardness profile, compressive strength, and the microstructure along the building direction were investigated and compared to the ageing curves. The results agree with the simulation and demonstrate that the intrinsic heat treatment may allow avoiding post-building heat treatment.

Microstructures and Fatigue Behavior of Additively Manufactured Maraging Steel Deposited on Conventionally Manufactured Base Plate

Maraging steel powder was additively deposited on the conventionally manufactured (CMed) maraging steel base plate by powder bed fusion type selective laser melting. Residual tensile stress was introduced into the additively manufactured (AMed) part due to the re-solidification of melted powder on the base plate. Tensile fatigue tests were conducted using the specimens having hybrid structure of AMed and CMed parts. The fatigue strengths of the specimens with hybrid structure were lower than those of the CMed specimens because fatigue cracks predominantly initiated at the defects in the AMed part. Two kinds of post-aging treatments could increase the hardness of the AMed and CMed parts, while had little effect on the fatigue strengths. The maximum size of the defects in the AMed part of the specimen was estimated based on the statistics of extremes. The fatigue limits of the as-built and post-aged samples were estimated by the linear elastic fracture mechanics approach. However, the predicted values were slightly higher than the experimental values.

Concurrent improvement of strength and ductility in heat-treated C300 maraging steels produced by laser powder bed fusion technique

Abstract In this work, C300 maraging steel powder feedstocks at different titanium contents (0.72 and 1.17 wt%) were additively manufactured using the laser powder bed fusion (LPBF) technique to systematically study the mechanical behavior of the material in both as-built and heat-treated conditions. X-ray diffraction techniques along with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) were employed to investigate the microstructural characteristics and phase formation in the as-built and heat-treated samples. After heat-treating at 490 °C for 6 h, the HighTi maraging steel showed higher strength and ductility (2057.74 MPa and 4.05%). The microstructural characterization proved that this alloy contains a higher amount of reverted austenite (17.89 wt%), which resulted at higher strength as results of the transformation induced plasticity (TRIP) effect. In terms of ductility improvement, the fiber/copper texture developed in the HighTi sample provided a higher driving force to transform the reverted austenite to martensite. As the TEM analyses revealed, needle-shaped Ni3Ti and spherical Ni3Mo precipitates were found in both LowTi and HighTi alloys, where the HighTi one showed higher volume fraction of Ni3Ti precipitates, and consequently, higher values of tensile strength, which can be explained, based on the Orowan mechanism.

Interface engineering of additively manufactured maraging steel-H13 bimetallic structures

This paper presents a study that aims to modify the interfacial characteristics of maraging steel-H13 bimetal structures through heat treatment procedures. Laser powder bed fusion (LPBF) was used to deposit maraging steel powder (MS1) on H13 hot work tool steel blocks. Subsequently, printed samples went through two different treatment cycles: (i) solution treatment, and (ii) aging treatment recommended for maraging steel. The microstructure, grain morphology, and mechanical response of MS1-H13 bimetals were assessed and compared with the as-built condition. Scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) techniques were used to analyze the interfacial modification upon heat treatment. Using uniaxial tensile testing and microhardness measurements along with 2D nanoindentation mapping, the mechanical properties of bimetal structures were correlated to the microstructural evolution of the samples during different heat treatments. Although the aging treatment was not effective to induce tangible microstructure changes, the solution treatment succeeded in the modification of MS1-H13 interface. A fully lath martensitic morphology was promoted across the interface, eliminating microstructure and hardness inhomogeneity as well as interface distinction between both sides. Finally, the solution treatment enhanced the mechanical properties of MS1-H13 bimetal structure by tripling the ultimate tensile strength.

Selective Laser Melting of 18NI-300 Maraging Steel.

In the present study, 18% Ni 300 maraging steel powder was processed using a selective laser melting (SLM) technique to study porosity variations, microstructure, and hardness using various process conditions, while maintaining a constant level of energy density. Nowadays, there is wide range of utilization of metal technologies and its products can obtain high relative density. A dilatometry study revealed that, through heating cycles, two solid-state effects took place, i.e., precipitation of intermetallic compounds and the reversion of martensite to austenite. During the cooling process, one reaction took place (i.e., martensitic transformation), which was confirmed by microstructure observation. The improvements in the Rockwell hardness of the analyzed material from 42 ± 2 to 52 ± 0.5 HRC was improved as a result of aging treatment at 480 °C for 5 h. The results revealed that the relative density increased using laser speed (340 mm/s), layer thickness (30 µm), and hatch distance (120 µm). Relative density was found approximately 99.3%. Knowledge about the influence of individual parameters in the SLM process on porosity will enable potential manufacturers to produce high quality components with desired properties.

Design and analysis of spur gear manufactured by DMLS process

The objective of this work is to use advanced manufacturing process i.e. Direct Metal Laser Sintering (DMLS) to produce complex design component such as spur gear. In this view, spur gear of gear box of vehicle model TATA super ACE mint is considered. 3D modeling of the spur gear is done using Solidworks software by considering the design parameters of the spur gear. Design calculations of Spur gear are done as per Lewis equation and Castigliano’s equation analytically. Finite Element analysis software ANSYS is used to study the equivalent von mises stress and the total deformation developed in the spur gear for the given torque and compare with the analytical results. In this study spur gear is manufactured using DMLS by using maraging steel powder. The optimized process parameters were used to manufacture the spur gear and these types of gears can be used in any power transmission system.

Effect of SLM Process Parameters on Relative Density of Maraging Steel (18Ni-300) Formed Parts

Taking maraging steel (18Ni300) powder as the research object, the influence of the density of forming parts such as laser power p, scanning speed v, scanning spacing s and powder thickness h during the rapid forming process of SLM laser was studied by orthogonal test. The experimental results show that the laser power and scanning spacing have a significant effect on the density of the molded part, while the powder thickness and scanning speed have no significant effect on the relative density of the molded part. The order of importance of the influence of each factor on the compactness of the formed part is the laser power, the scanning spacing, the scanning speed, and the powder thickness. The best combination of process parameters is a laser power of 260 W, a scanning speed of 700 mm/s, a scanning spacing of 0.11 mm, and a powder thickness of 0.02 mm. When the laser volume energy density is between 70 J/mm3 and 185 J/mm3, the relative density can reach more than 99%, and it can increase to 99.99% during this interval.

Relationship between the Size and Inner Structure of Particles of Virgin and Re-Used MS1 Maraging Steel Powder for Additive Manufacturing.

Additive manufacturing (AM) is today in the main focus—and not only in commercial production. Products with complex geometry can be built using various AM techniques, which include laser sintering of metal powder. Although the technique has been known for a quite long time, the impact of the morphology of individual powder particles on the process has not yet been adequately documented. This article presents a detailed microscopic analysis of virgin and reused powder particles of MS1 maraging steel. The metallographic observation was performed using a scanning electron microscope (SEM). The particle size of the individual powder particles was measured in the SEM and the particle surface morphology and its change in the reused powder were observed. Individual particles were analyzed in detail using an SEM with a focused ion beam (FIB) milling capability. The powder particles were gradually cut off in thin layers so that their internal structure, chemical element distribution, possible internal defects, and shape could be monitored. Elemental distribution and phase distribution were analyzed using EDS and EBSD, respectively. Our findings lead to a better understanding and prediction of defects in additive-manufactured products. This could be helpful not just in the AM field, but in any metal powder-based processes, such as metal injection molding, powder metallurgy, spray deposition processes, and others.

Crush performance of additively manufactured maraging steel microlattice reinforced plates

Additive metal manufacturing techniques, in particular laser-based powder bed fusion methods, are revolutionary in their capabilities to fabricating new classes of lightweight and complex materials called metallic microlattices. In this paper, a microlattice structure was designed for energy absorption purposes and further additively manufactured using maraging steel (Maraging300) powder through Laser-powder bed fusion (L-PBF) technique. In addition, several cylindrical bars and cubes in horizontal and vertical directions were manufactured to perform uniaxial tensile and compression tests on bulk L-PBF Maraging300. The manufactured microlattices were characterized using different electron microscopy techniques including scanning electron microscopy and micro-CT analysis to ensure that the desired structural integrity was achieved. In addition, the microlattice was then crushed using a universal mechanical testing machine to evaluate its performance experimentally under quasi-static uniaxial compressive loading conditions. Along with the crush, a nonlinear finite element model with predictive capabilities was then developed using commercial package (LS-DYNA) for axial crush of the microlattice to compare its expected performance. Two finite element models are developed using the as-built geometry from the printed lattice, and the as-designed geometry. The effect of model parameters is discussed and very good agreement between the experimental results and the finite element prediction was observed. Finally statistical analysis of the model and failure analysis of the crushed lattice is presented.