Authors:
Elin Olsson (1), Jean-Marc Lardon (2), Nicolas Stern (3), Stefan Sundin (1)
1- Erasteel, Sweden
2- Aubert&Duval, France
3- Erasteel, France
Abstract:
Martensitic stainless steels are highly alloyed in C, Cr and Mo for hardness and corrosion resistance and often in V for increased wear resistance. Due to the high alloying content, powder metallurgy (PM) including gas atomization and hot isostatic pressing (HIP) is the best technique to eliminate segregation and thus to increase properties such as strength, fatigue resistance etc. However, further improvement of properties is made possible thanks to the recent developments of gas atomization process, which give very low levels of non-metallic inclusions. High cleanliness of PM material is well known to be critical for good polishing ability, fatigue resistance, strength etc. This paper describes results regarding the effect of cleanliness and heat treatment on the impact toughness and salt spray corrosion resistance of PM martensitic stainless grades containing 14 % Cr, more than 2% C and 10% Mo + V.
DOI:
https://doi.org/10.59499/EP235764056
Authors:
Songyi Kim (KITECH, Korea, Republic of) Dohun Kwon (KITECH, Korea, Republic of) Hwijun Kim (KITECH, Korea, Republic of)
Abstract:
Nickel-based oxide dispersion strengthened (Ni-ODS) alloys are promising materials for high-temperature applications due to their excellent mechanical properties.This study investigates the effects of composition and dispersoid additions on the high-temperature strength of Ni-ODS alloys. Alloys were made by mechanical alloying and vacuum induction hot pressing. FE-SEM and EDS analysis were performed for microstructure analysis, and Gleeble test was performed to evaluate the high temperature mechanical properties. The results showed that the Nb-Si and Y2O3 composite dispersion strengthened alloy exhibited excellent high-temperature mechanical properties by effectively suppressing grain growth and dislocation motion in the alloy. Based on these findings, Ni-ODS alloys have significant potential for application in aerospace and power generation industries, where high-temperature strength and stability are critical.
DOI:
https://doi.org/10.59499/EP256766938
Authors:
Tsukasa Shirafuji (Kobe Steel, Ltd., Japan), Yuji Taniguchi (Kobe Steel, Ltd., Japan)
Abstract:
The fatigue strength of sintered steel is normally lower than that of conventional low-alloyed steel, such as JIS SCr420 and JIS SCM415 and so on,The fatigue strength of sintered steel is normally lower than that of conventional low-alloyed steel, such as JIS SCr420 and JIS SCM415 and so on, due to the porosities inside the material. However, it has been reported that tooth bending fatigue strength of sintered gears manufactured from 46F4H (0.5Ni-1.0Mo Pre-alloyed Steel Powder) is improved by surface-rolling and that the fatigue strength is equal to or higher than that of the gear manufactured from the wrought steel. In this study, we found that the reason why surface-rolled sintered steel gears have high fatigue strength is caused by both a decrease in size of the initiation fatigue crack due to eliminate the porosities in the vicinity of surface of the gear, and high compressive residual stress.
DOI:
https://doi.org/10.59499/WP225364378
Authors:
Maheswaran Vattur Sundaram (1), Fredrik Vinnerborg (1)
1- Höganäs AB, Sweden
Abstract:
Astaloy® CrS is a Cr pre-alloyed water-atomised powder containing 0.85wt.%Cr and 0.15wt.%Mo, developed as a sustainable alternative to Fe-Cu-C PM steels. For applications demanding higher performance, secondary operations such as heat treatments(HT) are necessary. Carburising is one HT process to improve surface hardness, wear resistance, and fatigue strength, leading to superior performance. For Fe-Cu-C materials, gas carburising(GC) is conventionally used, but for Cr pre-alloyed materials, low-pressure carburising(LPC) is preferred since it prevents oxidation. This investigation assesses the processing capabilities and the material requirements for successful heat treatment of CrS. To achieve this, LPC and GC were performed on both CrS and Fe-Cu-C samples with densities ranging from 7.1 to 7.4 g/cm3, sintered at 1120°C. The results indicated a higher static and fatigue performance after GC for CrS than the Fe-Cu-C. LPC provides better control of case depth for varying densities but requires a material with better hardenability for gas quenching.
DOI:
https://doi.org/10.59499/EP246278537
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Authors:
Toshiko Osada (Tokyo Metropolitan University, Japan), Satoshi Kobayashi (Tokyo Metropolitan University, Japan), Yoshiyuki Kato (Kato Professional Engineer office, Japan), Kenji Yokoyama (ExOne, K.K., Japan)
Abstract:
Metal binder jet 3D printing is suitable for fabricating metal parts in small quantity and many varieties in a short period of time. Fine powders for metal injection molding are used for binder jet 3D printer. Powders need to flow during recoating to the powder bed, and also after that they need to show high density for enough strength of green parts for handling. In this study, powder characteristics for binder jet 3D printing is focused, and effect of distance between powders on the printing and sintering properties of metal binder jet 3D printing is clarified.
DOI:
https://doi.org/10.59499/WP225367565
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Authors:
Miren Aristizabal (Ceit, Spain), Unai Galech (Ceit, Spain), Rafael Soler (ITP-Aero, Spain), Estibaliz Paños (ITP-Aero, Spain), Iñigo Iturriza (Ceit, Spain)
Abstract:
Gas atomised powder is widely used for HIP applications thanks to its beneficial properties in terms of flowability, compactability and few interstitials. Generally, a wide range of powder particle size is used in HIP to increase the powder efficiency, flow and compaction. While thin particles have to deal with oxygen pick up, wider powders suffer from entrapped gas porosity. These issues have been analysed and related with the properties of HIPped high temperature Ni superalloy. Characterisation have been carried out by mean of chemical analyses, microstructural analyses and mechanical tests. Results show that thin powders are prone to form PPBS and large powders have higher content of argon and both led to a ductility reduction. As a conclusion, gas atomised powder combining wide particle size range showed the best property compromise for Astroloy, making it suitable for the production of elevated temperature components for high-efficiency new jet engines.
DOI:
https://doi.org/10.59499/WP225371919
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Authors:
Maheswaran Vattur Sundaram (Höganäs AB, Sweden), Fabien Currit (Höganäs AB, Sweden), Michael Andersson (Höganäs AB, Sweden), Dimitris Chasoglou (Höganäs AB, Sweden)
Abstract:
The properties and the performance of PM steels can be tailored and enhanced by performing an appropriate heat treatment process after sintering. Conventional gas carburising (CQT) is the most used process for PM steels, whereas for Cr-alloyed PM steels, casehardening by low-pressure carburising (LPC) is gaining interest due to its oxide free process and better control over case depth. Also, when combined with high-pressure gas quenching (GQ) it provides less distortion in the components. In this work, Cr-alloyed PM steel with and without Ni additions were evaluated after both the CQT and LPC heat treatment process. The mechanical properties and performances were evaluated, and the results obtained indicated a strong correlation between the obtained properties and resulting microstructures based on the alloying elements and optimised heat treatment process.
DOI:
https://doi.org/10.59499/WP225371514
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Authors:
Quentin Saby (INSA Lyon, France), Jean-Yves Buffière (INSA Lyon, France), Thomas Joffre (CTIPC, France), Peter Vikner (Aubert&Duval, France), Xavier Boulnat (INSA Lyon, France)
Abstract:
Laser Powder Bed Fusion (LPBF) is an additive manufacturing process used to produce conformal cooling injection molds with complex internal channels, mainly using cobalt-rich 18Ni300 maraging steel. Yet, built parts with this steel powder still demand improved toughness and fatigue strength. As an alternative, this work describes the manufacturibility of two alternative cobalt-free martensitic stainless steels by LPBF. After a quantitative characterisation of the microstructure, defects and mechanical properties of as-built parts, different heat treatments were performed to (i) age the precipitation-hardenable low-carbon maraging steel (CX) or (ii) temper the high-carbon martensitic steel (PM420). The hardness, tensile strength, ductility, impact energy and fatigue behavior of as-built and treated parts were compared. The influence of the microstructure and the critical defects on the mechanical behavior is discussed, with an emphasis on the fatigue life. Finally, the manufacturing of complex injection molds using PM420 powder was assessed.
DOI:
https://doi.org/10.59499/WP225372159
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Authors:
Sung Gue Heo (1,2), Seok-Jun Seo (2)
1- Korea Institute of Industrial Technology, Republic of Korea
2- Korea University, Seoul 02841, Republic of Korea
Abstract:
Mesoporous CuCo2O4 is interesting material for electrodes of high-performance supercapacitors because of their high surface area, controlled porosity and excellent electrochemical properties. In this work, mesoporous CuCo2O4 powders were synthesized using inverse micelle method and analyzed by X-ray diffraction (XRD) and Brunauer-Emmett-Teller analysis (BET). After heat-treatment at 250˚C in oxygen atmosphere, the mesoporous CuCo2O4 powders exhibited high specific surface area of 104 m2/g with pore size of 9 nm. The mesoporous CuCo2O4 electrodes achieved maximum specific capacitance of 132 Fg-1 in 6M of KOH electrolyte. This superior electrochemical supercapacitor property is mainly due to increased surface area.
DOI:
https://doi.org/10.59499/EP235764617
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Authors:
HyunJoong Kim (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of) Sung-Jae Jo (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of) Jongun Moon (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of) Jiwoon Lee (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of) Gian Song (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of) Soon-Jik Hong (Division of Advanced Materials Engineering, and Center for Advanced Materials and Parts of Powders (CAMP2), Kongju National University, Korea, Republic of)
Abstract:
Powder characteristics in Directed Energy Deposition (DED) processes significantly impact the final product quality, yet the role of moisture content remains underexplored. This study evaluates the impact of varying powder humidity levels on flowability, microstructure, and mechanical properties during the DED process. Powder with different moisture levels were analyzed for particle size distribution, moisture content, and oxide layer thickness. Results from Hall Flowmeter and Dynamic Avalanche testing revealed that higher moisture content reduced flowability. When applied to the DED process, reduced flowability affected the dimensional accuracy and surface roughness of the resulting alloys. Microstructural analysis showed that elevated moisture levels promoted coarse oxide formation, identified as MnSiO3 and Cr2O3 through EBSD analysis. Tensile tests revealed that the oxides decreased tensile strength and elongation. These findings highlight the necessity of maintaining low humidity storage conditions or pre-drying powders to ensure high-quality, defect-free components in AM processes.
DOI:
https://doi.org/10.59499/EP256779291
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Authors:
Matthew Dunstan (US Army Research Lab, USA), Brady Butler (US Army Research Lab, USA), Isaac Nault (US Army Research Lab, USA), James Paramore (US Army Research Lab, USA)
Abstract:
Cold Spray Additive Manufacturing (CSAM) is a solid-state additive technology where metal powders are accelerated through a converging-diverging Laval type nozzle using a pressurized carrier gas. These powders are then sprayed onto a substrate in the shape of the desired component and subsequently removed. As only low temperatures (<1000 °C) are used during CSAM, the strength of the component relies completely on particle deformation and interlocking as very little diffusional processing takes place in order to create metallurgical bonds. Post-spray heat treatments are often necessary in order for components to achieve mechanical properties similar to other additive techniques. In this work, the heat treatment process known as Thermohydrogen Reduction of Microstructure (THRM), which was initially developed for laser based additive manufacturing, is applied to Ti-6Al-4V components produced via CSAM. Its effect on density, microstructure, and tensile properties are examined.
DOI:
https://doi.org/10.59499/WP225365785
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Authors:
S Venkatesh Kumaran (1,3); Sri Bala Aditya Malladi (2); Eduard Hryha (2); Jose M Torralba (1,3)
1- IMDEA Materials, Madrid, Spain
2- Chalmers University of Technology, Göteborg, Sweden
3- Universidad Carlos III de Madrid, Spain
Abstract:
Manufacturing high entropy alloys (HEAs) using powder bed fusion-laser beam/Metal (PBF-LB/M) enables their production with minimal elemental segregation due to its inherently fast cooling rates resulting in excellent properties. So far, HEAs have been fabricated with fully pre-alloyed gas-atomized powders which makes it expensive and slower to explore new alloy compositions. In this work, for the first time, instead of pre-alloying, blended powders of CoCrF75, Ni625, Invar36, and pure Al powders were used as feedstock to develop a CoCrFeNiMoxAly HEA which consists of FCC phase in the metastable state. The process was successfully optimized, achieving relative densities greater than 99.8%. This method of mixing powders for PBF-LB/M enables rapid exploration of new HEAs and this work is expected to contribute to its successful application in the future.
DOI:
https://doi.org/10.59499/EP235762606
