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Laser powder bed fusion is a type of metal-based additive manufacturing method that can be customized for a given material through modification of process parameters, resulting in changes to the overall quality and mechanical properties of the as-built component. Optimal mechanical properties are typically achieved by performing experimental builds of fully dense components with multiple parameter sets and comparing the resulting mechanical properties. Additionally, AM allows geometric freedom that can be utilized to produce structures tailored for energy absorption, such as cellular structures or lattice structures. There is limited previous work of scaling effects on mechanical properties of cellular structures. The first part of this work aims to determine process parameters that result in the best overall mechanical properties of L-PBF manufactured maraging 300 steel. This work then uses the optimal parameters to produce cellular structures scaled both uniformly and selectively to perform mechanical and physical analysis on their response.

L'acier maraging inoxydable MLX17, développé et élaboré par Aubert & Duval, est une nuance candidate pour des applications dans le domaine de l’aéronautique. Cette nuance possède un fort potentiel en termes de résistance mécanique qui dépasse celle des autres nuances inoxydables. Cependant, elle s’avère sensible à la vitesse de refroidissement après revenu, qui influence directement la ténacité. La recherche des origines scientifiques de la dégradation de la ténacité lorsque la vitesse de refroidissement après revenu diminue (refroidissement à l'air par rapport à un refroidissement à l'eau) constitue l’objectif majeur de cette thèse. Un suivi des modifications microstructurales de la nuance, selon différentes conditions de revenu a été réalisé. Une démarche intégrant différentes échelles d'observation (de l’échelle macroscopique jusqu'à l'échelle atomique) s’est imposée au vu de la complexité de la microstructure. Parallèlement, l’étude des propriétés mécaniques en traction et en résistance à la propagation brutale de fissure a été menée afin de s’attacher en permanence à corréler le comportement mécanique à l’évolution microstructurale observée pour les différentes conditions de revenu. Les analyses par dilatométrie et par sonde atomique tomographique ont permis de mettre en évidence la formation d’un complément de précipitation, à l'origine de la dégradation de la ténacité. Pour permettre une meilleure maîtrise du complément de précipitation et le rendre moins fragilisant, une modification des conditions de revenu a été proposée. Cette alternative a permis d'obtenir une amélioration du compromis résistance/ténacité. / The stainless maraging steel MLX17, produced and developed by Aubert & Duval, is a candidate for applications in the field of the aeronautics. This steel possesses a high potential in term of mechanical resistance that exceeds that of the other stainless steels. However, the fracture toughness of this grade proves to be sensitive to the cooling rate after aging, resulting of a dispersal of this property. The research of the scientific origins of the degradation of the fracture toughness by a decrease of the cooling rate (air cooling in comparison to water cooling) is the main objective of this thesis. The microstructure was observed for several aging conditions. An approach using various scales (from micrometric to atomic scale) was necessary because of the complexity of the microstructure. In parallel, the study of tensile mechanical properties and resistance to propagation of cracks was led. The aim was to correlate the mechanical behavior to the microstructural evolution observed for the aging conditions investigated. Microstructural analyses by dilatometry and atomic tomography probe have shown the formation of a complementary precipitation of the hardening phase, responsible of the fracture toughness deterioration. In order to have a better control of this additional precipitation and to make it less fragile, a modification of the aging conditions was proposed. This alternative enabled an improvement of the trade-offs between the high strength and the fracture toughness.

Atlas Copco Secoroc AB are searching after new bulk materials for drill heads that are used in percussive drilling in order to improve their strength and durability. The aim of this project is to assist Atlas Copco in this search and provide them with further information regarding material properties, alloying elements, suppliers, etc. A literary study was carried out in order to identify materials that had UTS and KIC more than or equal to 1700 MPa and 70 MPa*m1/2, respectively. Materials that fulfilled these criteria were T250 grade maraging steel, Cobalt free maraging steel, High cobalt maraging steel, 300 grade maraging steel, AerMet 100, AF1410, S53, M54, 300M, 4340M and PremoMet. These were categorized into maraging steels, high alloy secondary hardened steels, and low alloy steels, and were then further researched.  The material with the highest combination of UTS and KIC was M54 followed by AerMet 100; while AF1410 had the highest KIC but a low UTS, and PremoMet had the highest UTS but a low KIC. Maraging steels and HASH steels have a similar price range, while low alloy steels are much cheaper.

Atlas Copco Secoroc AB are searching after new bulk materials for drill heads that are used in percussive drilling in order to improve their strength and durability. The aim of this project is to assist Atlas Copco in this search and provide them with further information regarding material properties, alloying elements, suppliers, etc. A literary study was carried out in order to identify materials that had UTS and KIC more than or equal to 1700 MPa and 70 MPa*m^1/2, respectively. Materials that fulfilled these criteria were T250 grade maraging steel, Cobalt free maraging steel, High cobalt maraging steel, 300 grade maraging steel, AerMet 100, AF1410, S53, M54, 300M, 4340M and PremoMet. These were categorized into maraging steels, high alloy secondary hardened steels, and low alloy steels, and were then further researched. The material with the highest combination of UTS and KIC was M54 followed by AerMet 100; while AF1410 had the highest KIC but a low UTS, and PremoMet had the highest UTS but a low KIC. Maraging steels and HASH steels have a similar price range, while low alloy steels are much cheaper.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / AÃos maraging sÃo ligas Ni-Co-Mo-Ti de ultra-alta resistÃncia e vasta aplicaÃÃo que vai desde a indÃstria bÃlica e nuclear atà componentes aeronÃuticos, vasos de pressÃo e a indÃstria esportiva. Atualmente estes aÃos vÃm sendo estudados para utilizaÃÃo em rotores de alta velocidade de motores de histerese. Os aÃos maraging apresentam algumas vantagens em comparaÃÃo a outros tipos de aÃos e ligas, pois apresentam nÃveis de resistÃncia mecÃnica extremamente elevados, excelente conformabilidade no estado solubilizado e grande capacidade de endurecer por envelhecimento. A utilizaÃÃo destes aÃos em motores de histerese à o motivo pelo qual se estudam suas propriedades magnÃticas. Para este fim, o material deve apresentar, alÃm de elevada resistÃncia mecÃnica, caracterÃsticas tÃpicas de materiais magneticamente macios. As propriedades magnÃticas do material sÃo mostradas e discutidas com o objetivo de determinar os melhores tipos de tratamento para utilizaÃÃo do aÃo nas condiÃÃes requeridas. AnÃlises de textura foram realizadas e discutidas com o objetivo de determinar a textura existente no material, bem como sua direÃÃo de fÃcil magnetizaÃÃo. As quantificaÃÃes das fases para as diferentes condiÃÃes de tratamento termomecÃnico foram realizadas por difraÃÃo de raios-X, atravÃs do mÃtodo de comparaÃÃo direta com o objetivo de analisar a influÃncia da austenita na textura, resistÃncia mecÃnica e propriedades magnÃticas do material. Ensaios de dureza foram realizados com o objetivo de analisar as propriedades mecÃnicas do material. As anÃlises revelaram que praticamente todas as amostras possuem os mesmos componentes de textura e a direÃÃo de fÃcil magnetizaÃÃo <100> apresenta-se no plano da chapa rotacionada de 45 em relaÃÃo à direÃÃo de laminaÃÃo. As propriedades magnÃticas medidas mostram que todas as amostras possuem os requisitos mÃnimos para utilizaÃÃo em motores de histerese, sendo as amostras com solubilizaÃÃo intermediÃria as menos indicadas a as amostras resfriadas em nitrogÃnio as mais indicadas para este tipo de aplicaÃÃo. / AÃos maraging sÃo ligas Ni-Co-Mo-Ti de ultra-alta resistÃncia e vasta aplicaÃÃo que vai desde a indÃstria bÃlica e nuclear atà componentes aeronÃuticos, vasos de pressÃo e a indÃstria esportiva. Atualmente estes aÃos vÃm sendo estudados para utilizaÃÃo em rotores de alta velocidade de motores de histerese. Os aÃos maraging apresentam algumas vantagens em comparaÃÃo a outros tipos de aÃos e ligas, pois apresentam nÃveis de resistÃncia mecÃnica extremamente elevados, excelente conformabilidade no estado solubilizado e grande capacidade de endurecer por envelhecimento. A utilizaÃÃo destes aÃos em motores de histerese à o motivo pelo qual se estudam suas propriedades magnÃticas. Para este fim, o material deve apresentar, alÃm de elevada resistÃncia mecÃnica, caracterÃsticas tÃpicas de materiais magneticamente macios. As propriedades magnÃticas do material sÃo mostradas e discutidas com o objetivo de determinar os melhores tipos de tratamento para utilizaÃÃo do aÃo nas condiÃÃes requeridas. AnÃlises de textura foram realizadas e discutidas com o objetivo de determinar a textura existente no material, bem como sua direÃÃo de fÃcil magnetizaÃÃo. As quantificaÃÃes das fases para as diferentes condiÃÃes de tratamento termomecÃnico foram realizadas por difraÃÃo de raios-X, atravÃs do mÃtodo de comparaÃÃo direta com o objetivo de analisar a influÃncia da austenita na textura, resistÃncia mecÃnica e propriedades magnÃticas do material. Ensaios de dureza foram realizados com o objetivo de analisar as propriedades mecÃnicas do material. As anÃlises revelaram que praticamente todas as amostras possuem os mesmos componentes de textura e a direÃÃo de fÃcil magnetizaÃÃo <100> apresenta-se no plano da chapa rotacionada de 45 em relaÃÃo à direÃÃo de laminaÃÃo. As propriedades magnÃticas medidas mostram que todas as amostras possuem os requisitos mÃnimos para utilizaÃÃo em motores de histerese, sendo as amostras com solubilizaÃÃo intermediÃria as menos indicadas a as amostras resfriadas em nitrogÃnio as mais indicadas para este tipo de aplicaÃÃo. / Maraging steels are alloys of Ni-Co-Ti-Mo ultra-high resistance and wide application ranging from the defense industry and nuclear power to aircraft components, pressure vessels and the sports industry. Currently these steels have been studied for use in high speed rotors hysteresis motors. The maraging steel have some advantages compared to other types of steels and alloys, as have levels of extremely high mechanical strength, excellent conformability in the solubilized state and great ability to harden by aging. The use of these steels in hysteresis motors is why we study their magnetic properties. To this end, the material must have, and high mechanical strength characteristics typical of magnetically soft material. The magnetic properties of the material are shown and discussed in order to determine the best types of treatment for use in the steel requirements. Textural analyzes were performed and discussed in order to determine the existing texture in the material, as well as its direction of easy magnetization. The quantification of phases for different conditions of thermomechanical treatment was performed by X-ray diffraction, using the method of direct comparison with the objective of analyzing the influence of austenite texture, mechanical and magnetic properties of the material. Hardness tests were performed to analyze the mechanical properties of the material. The analysis revealed that virtually all samples have the same texture components and the direction of easy magnetization <100> is presented in the plane of the plate rotated 45  relative to the direction of lamination. The magnetic properties measurements show that all samples have the minimum requirements for use in motor hysteresis, and the samples with the least intermediate solubilization indicated the samples cooled in nitrogen the most suitable for this type of application. / Maraging steels are alloys of Ni-Co-Ti-Mo ultra-high resistance and wide application ranging from the defense industry and nuclear power to aircraft components, pressure vessels and the sports industry. Currently these steels have been studied for use in high speed rotors hysteresis motors. The maraging steel have some advantages compared to other types of steels and alloys, as have levels of extremely high mechanical strength, excellent conformability in the solubilized state and great ability to harden by aging. The use of these steels in hysteresis motors is why we study their magnetic properties. To this end, the material must have, and high mechanical strength characteristics typical of magnetically soft material. The magnetic properties of the material are shown and discussed in order to determine the best types of treatment for use in the steel requirements. Textural analyzes were performed and discussed in order to determine the existing texture in the material, as well as its direction of easy magnetization. The quantification of phases for different conditions of thermomechanical treatment was performed by X-ray diffraction, using the method of direct comparison with the objective of analyzing the influence of austenite texture, mechanical and magnetic properties of the material. Hardness tests were performed to analyze the mechanical properties of the material. The analysis revealed that virtually all samples have the same texture components and the direction of easy magnetization <100> is presented in the plane of the plate rotated 45  relative to the direction of lamination. The magnetic properties measurements show that all samples have the minimum requirements for use in motor hysteresis, and the samples with the least intermediate solubilization indicated the samples cooled in nitrogen the most suitable for this type of application.

Diploma theses is focused on welding experiment of maraging steel by use Yb-YAG laser. Experimet is based on testing of combination steel 11321 and maraging steel. Domex420MC, Domex720MC a QSE380. In theoretical part there are described laser technology of welding, weld defect, maraging steel and inspection of welded joints. In experimental part there are porposed test and made mechanical test of weld as transverse tensile test, bend tests, Erichsen cupping test, Vickers hardness test and makroscopic and microscopic examination of welds. In conclusion there are analysis of the experiment results.

No description available.

Additive manufacturing methods for steel are competing against commercial production in an increasing pace. The geometry freedom together with the high strength and toughness due to extreme cooling rates make this method viable to use for high-performance components. The desirable material properties originate from the ultrafine grain structures. The production is often followed by a post hardening heat treatment to induce precipitation of other phases. The printing process does however bring several challenges such as cracking, pore formation, inclusions, residual stresses and distortions. It is therefore important to be able to predict the properties such as temperature evolution and residual stresses of the resulting part in order to avoid time consuming trial-and-error and unnecessary material waste. In order to link different parts and length scales of the process, the integrated computational materials engineering framework can be used where linkage tools couples results of different length scales. 18Ni300 maraging steel is a material that has been used extensively to produce parts by additive manufacturing, but there is still a wide scope for optimising the process and properties. In this thesis, the integrated computational materials engineering inspired framework is applied to link the process to the microstructure, which dictates the properties. Temperature evolution strongly influences the material properties, residual stresses and distortion in additive manufacturing. Therefore, simulations of temperature evolution for a selective laser melted 18Ni300 maraging steel have been performed by Simufact Additive and linked with the microstructure prediction tools in Thermo-Calc and DICTRA. Various printing parameters have been examined and resulting temperatures, cooling rates, segregations and martensitic start temperatures compared for different locations of the build part. Additionally, residual stresses and distortions were investigated in Simufact. It was found that higher laser energy density caused increased temperatures and cooling rates which generally created larger segregations of alloying elements and lower martensitic start temperatures at the intercellular region. There is however an impact from cooling rate and temperature independent of the energy density which makes energy density not an individual defining parameter for the segregations. By decreasing the baseplate temperature, lower temperatures below the martensitic start temperature were reached, enhancing martensite transformation. Primary dendrite arm spacing calculations were used to validate the cooling rates. The cell size corresponded well to literature of &lt;1 μm. Distortions and residual stresses were very small. The calibration was based according to literature and need experimental values to be validated. The integrated framework demonstrated in this thesis provides an insight into the expected properties of the additively manufactured part which can decrease and replace trial-and-error methods. / dditiva tillverkningsmetoder för stål tävlar mot kommersiell produktion i en ökande takt. Geometrifriheten tillsammans med hög styrka och slagseghet på grund av extrema kylhastigheter gör den här metoden intressant att använda för högpresterande komponenter. De önskvärda materialegenskaperna härstammar från den ultrafina mikrostrukturen. Processen följs ofta av en värmebehandlande härdning för att inducera utskiljningar av andra faser. Printing processen innebär dock flertalet utmaningar som exempelvis sprickbildning, porer, inneslutningar, restspänningar och förvrängningar. Det är därför intressant och viktigt att förutspå egenskaper såsom temperaturutveckling och restspänningar av den slutgiltiga komponenten för att minska tidskrävande ”trial-and-error” och onödigt materialsvin. För att länka ihop olika delar och längdskalor av processen kan ”the integrated computational materials engineering” strukturen användas där länkverktyg kopplar ihop resultat av olika längdskalor. 18Ni300 maraging stål är ett material som har använts till additivt tillverkade produkter i hög utsträckning men det finns fortfarande mycket utrymme för optimering av processen och egenskaperna. I den här avhandlingen, den ”integrated computational materials engineering” inspirerade tillvägagångssättet används för att länka processen med mikrostrukturen, vilken bestämmer egenskaperna. Temperaturutveckling påverkar kraftigt materialegenskaper, restspänningar och deformation vid additiv tillverkning. Förutsägelse av temperatur för ett selektivt lasersmält 18Ni300 stål har därför genomförts i Simufact Additive och länkats med mikrostruktursförutsägande redskapen Thermo-Calc och DICTRA. Olika maskinparametrar har undersökts och efterföljande temperaturer, kylhastigheter, segregeringar och martensitiska starttemperaturer jämförts för olika delar av geometrin. Tilläggningsvis var även restspänningar och deformationer undersökta i Simufact. Det konstaterades att högre energidensitet för lasern orsakade högre temperaturer och kylhastighet vilket generellt skapade mer segregeringar av legeringsämnen och lägre martensitisk starttemperatur i de intercellulära områdena. Det är däremot en gemensam påverkan av kylhastighet och temperatur vilket gör att energidensitet inte är den enskilda bestämmande parametern över segregeringarna. Genom att sänka temperaturen på basplattan uppnåddes lägre temperaturer under den martensitiska starttemperaturen vilket förenklar den martensistiska omvandlingen. Beräkningar av primär dendritisk armlängd användes för att validera kylhastigheterna. Cellstorleken överensstämde bra med litteraturen på &lt;1 μm. Deformationer och restspänningar var väldigt små. Kalibreringarna baserades på litteraturvärden och kräver experimentella värden för att valideras. Den integrerade strukturen  som demonstreras i den här avhandlingen förser en insikt i de förväntade egenskaperna av en additivt tillverkad del vilket kan minska och ersätta ”trial-and-error” metoder.

This work investigates the velocity-dependent coefficient of friction between concrete and 300 Maraging steel over short displacements. A modified torsional Hopkinson bar is utilized for rotating thin-walled steel rings in contact with a concrete disk under static precompression. Rotational velocity is varied between tests to determine the velocity dependence of the friction coefficient. Normal force is varied between certain tests to determine the pressure dependence of the friction coefficient between the concrete and steel. Three different types of concrete are tested to deduce any composition effect on the friction coefficient. Dry and greased conditions’ impact on the friction coefficient are also evaluated. Lastly, the displacement dependence (fade) is considered for the concrete with regards to the steel. Discussion of the usefulness of this data in modeling and experimentation of impact between concrete and steel is disclosed.