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C250 maraging steel, known for its high strength and good toughness, is ideal for applications requiring exceptional high strain rate properties. Its carbon-free composition is suitable for the directed energy deposition-arc (DED-Arc) method, an additive manufacturing (AM) process with a low cost and high deposition rate. However, the thermal cycles in DED-Arc significantly impact the microstructure of C250 alloy. This could lead to undesirable high strain rate properties, necessitating post-fabrication heat treatment. Research gaps remain in understanding the microstructure and dynamic deformation response of DED-Arc fabricated C250 steel. Besides, AM enables fabricating complex geometries, but accurate constitutive models governing the stress-strain relationship of materials are essential for reliable finite element analysis (FEA) predictions of dynamic deformation. Yet, no reliable models have been proposed to predict the dynamic deformation behaviors of DED-Arc built C250 alloy. Therefore, this study aims to investigate the microstructure and dynamic deformation responses of DED-Arc built C250 steel at different strain rates and temperatures and to develop appropriate constitutive models based on the observed flow behavior. Microstructure analyses indicate the absence of strengthening precipitates and the presence of retained austenite phase in as-built DED-Arc C250 steel, leading to inferior dynamic mechanical performance compared to heat-treated wrought C250 alloy. However, commercial heat treatment significantly improves the dynamic mechanical performance of heat-treated DED-Arc C250 steel, making it comparable to that of the heat-treated wrought C250 alloy. This substantial improvement is mainly attributed to the formation of nano-sized, needle-shaped, and coherent Ni3Mo strengthening precipitates during the heat treatment. Modifications are made to the Johnson-Cook constitutive models to predict the dynamic deformation behaviors of as-deposited and heat-tre

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Dental implants are vital in modern dentistry, offering a durable and effective solution for various dental issues. Since their introduction for edentulous jaws, implants have been recognized as a reliable option for replacing missing teeth. Recent advancements in digital engineering, such as cone beam computed tomography (CBCT) and computer-aided design (CAD) techniques, have further enhanced implant dentistry. High-quality CT scans and sophisticated segmentation software now facilitate the reverse engineering of implants, enabling the creation of patient-specific root analog implants. This process involves generating computer models that accurately replicate anatomical features, including teeth. Direct metal laser sintering (DMLS), an additive manufacturing method, can then produce these customized implants, offering a faster and more patient-friendly alternative to traditional methods. The project's goal is to advance implant dentistry by developing a semi-automated protocol for patient-specific implants. This protocol aims to promote the adoption of root analog implants produced via DMLS. The developed tools will help dental professionals manage complex cases more effectively, benefiting many patients and improving implant survival rates. This approach also simplifies the implantation process, reducing the technological burden on dental professionals. Initially focused on custom-made implants, the project revealed inconsistencies in current fabrication methods, highlighting the need for standardized procedures. Our key achievements include a comprehensive review of custom-made root analog implants (RAIs). We developed a modeling protocol to convert CBCT scans of roots into scaffold roots, tested it with plastic prototypes, and manufactured titanium RAIs, which were CT-scanned and mechanically tested. Our findings indicate that the field of custom-made implant fabrication is still developing, with no standardized methods or clear guidelines. The modeling protocol

Considerable focus has been directed toward investigating the interdiffusion coefficients in binary systems, primarily due to their pivotal role in metallurgical processes and material performance assessments. An essential parameter in this context is the isothermal concentration-dependent interdiffusion coefficient. While interdiffusion coefficients are widely recognized as being influenced by temperature and concentration, the element of time can exert substantial influence due to the presence of diffusion-induced stress (DIS) within the system. The present research experimentally investigates the effect of time on concentration-dependent interdiffusion and impurity diffusion coefficients in Cu-Ni binary systems and their alloy compositions. The investigation delves into the effect of solute source concentration and anomalous behaviors of temperature as the attributable indications of DIS at play. To implement the research work, a newly devised numerical diffusion model by Olaye and Ojo [20] is integrated with a forward simulation approach in this study. This model incorporates different atomic diffusion coefficients and ensures solute conservation. The model also merges fully explicit finite difference analyses with the Leapfrog/Dufort-Frankel scheme, thus enabling the determination of concentration-dependent interdiffusion coefficients. This approach overcomes the limitations associated with traditional techniques like the Boltzmann-Matano, Hall, Wagner and Sauer-Freise methods. By applying this method, both the interdiffusion and impurity diffusion coefficients are investigated at various diffusion times. The results reveal that the interdiffusion and impurity diffusion coefficients show time variations as a result of DIS in the system. This phenomenon contrasts the widely accepted notion of the interdiffusion coefficient being solely dependent on concentration and temperature without considering time. Overlooking this critical aspect could have substantial imp

The influence of pulsed laser beam welding (LBW) parameters on theweld geometry and imperfections of a new nickel-based superalloy called G27 wasstudied by a statistical design of experiment, and the microstructures of the weldfusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. Noevidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weldimperfections, such as undercut and underfill, were also hardly observed. The pulsefactor significantly influenced all the responses, i.e., minimum weld width (Wm),root excess weld metal, and average pore diameter, whereas welding travel speedsignificantly influenced Wm and root excess weld metal. Power and interactionbetween pulse frequency*pulse factor were statistically significant in influencingthe root excess weld metal and average pore diameter, respectively. The pulsefrequency and interactions between power*travel speed, power*pulse factor,power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequencydid not significantly influence any response. Microsegregation pattern that occursduring weld solidification leads to the formation of Nb-rich MC carbides and Nbrich Laves phase as the major secondary phase constituents in the FZ of as-weldedG27. The presence of brittle Laves phase requires careful consideration whendeveloping suitable post-weld heat treatment of G27., CC-BY-NC 4.0This study is based on the research conducted within the FEAST project (WeldFeasibility Heat Treatment Studies of New Superalloys, registration number 2019-02787) funded by the Swedish funding agency VINNOVA

The influence of pulsed laser beam welding (LBW) parameters on the weld geometry and imperfections of a new nickel-based superalloy called G27 was studied by a statistical design of experiment, and the microstructures of the weld fusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. No evidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weld imperfections, such as undercut and underfill, were also hardly observed. The pulse factor significantly influenced all the responses, i.e., minimum weld width (Wm), root excess weld metal, and average pore diameter, whereas welding travel speed significantly influenced Wm and root excess weld metal. Power and interaction between pulse frequency*pulse factor were statistically significant in influencing the root excess weld metal and average pore diameter, respectively. The pulse frequency and interactions between power*travel speed, power*pulse factor, power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequency did not significantly influence any response. Microsegregation pattern that occurs during weld solidification leads to the formation of Nb-rich MC carbides and Nb-rich Laves phase as the major secondary phase constituents in the FZ of as-welded G27. The presence of brittle Laves phase requires careful consideration when developing suitable post-weld heat treatment of G27., CC BY NC 4.0

The influence of pulsed laser beam welding (LBW) parameters on theweld geometry and imperfections of a new nickel-based superalloy called G27 wasstudied by a statistical design of experiment, and the microstructures of the weldfusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. Noevidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weldimperfections, such as undercut and underfill, were also hardly observed. The pulsefactor significantly influenced all the responses, i.e., minimum weld width (Wm),root excess weld metal, and average pore diameter, whereas welding travel speedsignificantly influenced Wm and root excess weld metal. Power and interactionbetween pulse frequency*pulse factor were statistically significant in influencingthe root excess weld metal and average pore diameter, respectively. The pulsefrequency and interactions between power*travel speed, power*pulse factor,power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequencydid not significantly influence any response. Microsegregation pattern that occursduring weld solidification leads to the formation of Nb-rich MC carbides and Nbrich Laves phase as the major secondary phase constituents in the FZ of as-weldedG27. The presence of brittle Laves phase requires careful consideration whendeveloping suitable post-weld heat treatment of G27., CC-BY-NC 4.0This study is based on the research conducted within the FEAST project (WeldFeasibility Heat Treatment Studies of New Superalloys, registration number 2019-02787) funded by the Swedish funding agency VINNOVA

The influence of pulsed laser beam welding (LBW) parameters on the weld geometry and imperfections of a new nickel-based superalloy called G27 was studied by a statistical design of experiment, and the microstructures of the weld fusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. No evidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weld imperfections, such as undercut and underfill, were also hardly observed. The pulse factor significantly influenced all the responses, i.e., minimum weld width (Wm), root excess weld metal, and average pore diameter, whereas welding travel speed significantly influenced Wm and root excess weld metal. Power and interaction between pulse frequency*pulse factor were statistically significant in influencing the root excess weld metal and average pore diameter, respectively. The pulse frequency and interactions between power*travel speed, power*pulse factor, power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequency did not significantly influence any response. Microsegregation pattern that occurs during weld solidification leads to the formation of Nb-rich MC carbides and Nb-rich Laves phase as the major secondary phase constituents in the FZ of as-welded G27. The presence of brittle Laves phase requires careful consideration when developing suitable post-weld heat treatment of G27., CC BY NC 4.0

The influence of pulsed laser beam welding (LBW) parameters on theweld geometry and imperfections of a new nickel-based superalloy called G27 wasstudied by a statistical design of experiment, and the microstructures of the weldfusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. Noevidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weldimperfections, such as undercut and underfill, were also hardly observed. The pulsefactor significantly influenced all the responses, i.e., minimum weld width (Wm),root excess weld metal, and average pore diameter, whereas welding travel speedsignificantly influenced Wm and root excess weld metal. Power and interactionbetween pulse frequency*pulse factor were statistically significant in influencingthe root excess weld metal and average pore diameter, respectively. The pulsefrequency and interactions between power*travel speed, power*pulse factor,power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequencydid not significantly influence any response. Microsegregation pattern that occursduring weld solidification leads to the formation of Nb-rich MC carbides and Nbrich Laves phase as the major secondary phase constituents in the FZ of as-weldedG27. The presence of brittle Laves phase requires careful consideration whendeveloping suitable post-weld heat treatment of G27., CC-BY-NC 4.0This study is based on the research conducted within the FEAST project (WeldFeasibility Heat Treatment Studies of New Superalloys, registration number 2019-02787) funded by the Swedish funding agency VINNOVA

Considerable focus has been directed toward investigating the interdiffusion coefficients in binary systems, primarily due to their pivotal role in metallurgical processes and material performance assessments. An essential parameter in this context is the isothermal concentration-dependent interdiffusion coefficient. While interdiffusion coefficients are widely recognized as being influenced by temperature and concentration, the element of time can exert substantial influence due to the presence of diffusion-induced stress (DIS) within the system. The present research experimentally investigates the effect of time on concentration-dependent interdiffusion and impurity diffusion coefficients in Cu-Ni binary systems and their alloy compositions. The investigation delves into the effect of solute source concentration and anomalous behaviors of temperature as the attributable indications of DIS at play. To implement the research work, a newly devised numerical diffusion model by Olaye and Ojo [20] is integrated with a forward simulation approach in this study. This model incorporates different atomic diffusion coefficients and ensures solute conservation. The model also merges fully explicit finite difference analyses with the Leapfrog/Dufort-Frankel scheme, thus enabling the determination of concentration-dependent interdiffusion coefficients. This approach overcomes the limitations associated with traditional techniques like the Boltzmann-Matano, Hall, Wagner and Sauer-Freise methods. By applying this method, both the interdiffusion and impurity diffusion coefficients are investigated at various diffusion times. The results reveal that the interdiffusion and impurity diffusion coefficients show time variations as a result of DIS in the system. This phenomenon contrasts the widely accepted notion of the interdiffusion coefficient being solely dependent on concentration and temperature without considering time. Overlooking this critical aspect could have substantial imp

The influence of pulsed laser beam welding (LBW) parameters on the weld geometry and imperfections of a new nickel-based superalloy called G27 was studied by a statistical design of experiment, and the microstructures of the weld fusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. No evidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weld imperfections, such as undercut and underfill, were also hardly observed. The pulse factor significantly influenced all the responses, i.e., minimum weld width (Wm), root excess weld metal, and average pore diameter, whereas welding travel speed significantly influenced Wm and root excess weld metal. Power and interaction between pulse frequency*pulse factor were statistically significant in influencing the root excess weld metal and average pore diameter, respectively. The pulse frequency and interactions between power*travel speed, power*pulse factor, power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequency did not significantly influence any response. Microsegregation pattern that occurs during weld solidification leads to the formation of Nb-rich MC carbides and Nb-rich Laves phase as the major secondary phase constituents in the FZ of as-welded G27. The presence of brittle Laves phase requires careful consideration when developing suitable post-weld heat treatment of G27., CC BY NC 4.0

The influence of pulsed laser beam welding (LBW) parameters on theweld geometry and imperfections of a new nickel-based superalloy called G27 wasstudied by a statistical design of experiment, and the microstructures of the weldfusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. Noevidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weldimperfections, such as undercut and underfill, were also hardly observed. The pulsefactor significantly influenced all the responses, i.e., minimum weld width (Wm),root excess weld metal, and average pore diameter, whereas welding travel speedsignificantly influenced Wm and root excess weld metal. Power and interactionbetween pulse frequency*pulse factor were statistically significant in influencingthe root excess weld metal and average pore diameter, respectively. The pulsefrequency and interactions between power*travel speed, power*pulse factor,power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequencydid not significantly influence any response. Microsegregation pattern that occursduring weld solidification leads to the formation of Nb-rich MC carbides and Nbrich Laves phase as the major secondary phase constituents in the FZ of as-weldedG27. The presence of brittle Laves phase requires careful consideration whendeveloping suitable post-weld heat treatment of G27., CC-BY-NC 4.0This study is based on the research conducted within the FEAST project (WeldFeasibility Heat Treatment Studies of New Superalloys, registration number 2019-02787) funded by the Swedish funding agency VINNOVA

The influence of pulsed laser beam welding (LBW) parameters on the weld geometry and imperfections of a new nickel-based superalloy called G27 was studied by a statistical design of experiment, and the microstructures of the weld fusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. No evidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weld imperfections, such as undercut and underfill, were also hardly observed. The pulse factor significantly influenced all the responses, i.e., minimum weld width (Wm), root excess weld metal, and average pore diameter, whereas welding travel speed significantly influenced Wm and root excess weld metal. Power and interaction between pulse frequency*pulse factor were statistically significant in influencing the root excess weld metal and average pore diameter, respectively. The pulse frequency and interactions between power*travel speed, power*pulse factor, power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequency did not significantly influence any response. Microsegregation pattern that occurs during weld solidification leads to the formation of Nb-rich MC carbides and Nb-rich Laves phase as the major secondary phase constituents in the FZ of as-welded G27. The presence of brittle Laves phase requires careful consideration when developing suitable post-weld heat treatment of G27., CC BY NC 4.0

The influence of pulsed laser beam welding (LBW) parameters on the weld geometry and imperfections of a new nickel-based superalloy called G27 was studied by a statistical design of experiment, and the microstructures of the weld fusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. No evidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weld imperfections, such as undercut and underfill, were also hardly observed. The pulse factor significantly influenced all the responses, i.e., minimum weld width (Wm), root excess weld metal, and average pore diameter, whereas welding travel speed significantly influenced Wm and root excess weld metal. Power and interaction between pulse frequency*pulse factor were statistically significant in influencing the root excess weld metal and average pore diameter, respectively. The pulse frequency and interactions between power*travel speed, power*pulse factor, power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequency did not significantly influence any response. Microsegregation pattern that occurs during weld solidification leads to the formation of Nb-rich MC carbides and Nb-rich Laves phase as the major secondary phase constituents in the FZ of as-welded G27. The presence of brittle Laves phase requires careful consideration when developing suitable post-weld heat treatment of G27., CC BY NC 4.0

The influence of pulsed laser beam welding (LBW) parameters on theweld geometry and imperfections of a new nickel-based superalloy called G27 wasstudied by a statistical design of experiment, and the microstructures of the weldfusion zone (FZ) of the pulsed laser beam-welded G27 were characterized. Noevidence of cracks is found in the FZ and heat-affected zone (HAZ). Other weldimperfections, such as undercut and underfill, were also hardly observed. The pulsefactor significantly influenced all the responses, i.e., minimum weld width (Wm),root excess weld metal, and average pore diameter, whereas welding travel speedsignificantly influenced Wm and root excess weld metal. Power and interactionbetween pulse frequency*pulse factor were statistically significant in influencingthe root excess weld metal and average pore diameter, respectively. The pulsefrequency and interactions between power*travel speed, power*pulse factor,power*pulse frequency, travel speed*pulse factor, and travel speed*pulse frequencydid not significantly influence any response. Microsegregation pattern that occursduring weld solidification leads to the formation of Nb-rich MC carbides and Nbrich Laves phase as the major secondary phase constituents in the FZ of as-weldedG27. The presence of brittle Laves phase requires careful consideration whendeveloping suitable post-weld heat treatment of G27., CC-BY-NC 4.0This study is based on the research conducted within the FEAST project (WeldFeasibility Heat Treatment Studies of New Superalloys, registration number 2019-02787) funded by the Swedish funding agency VINNOVA

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This article is licensed under a Creative Commons Attribution 4.0 International License,This work is based on the research within the FEAST (Weld Feasibility Heat Treatment Studies of New Superalloys, registration number: 2019–02787) project funded by the Swedish funding agency VINNOVA.

CC-BY 4.0

This article is licensed under a Creative Commons Attribution 4.0 International License,This work is based on the research within the FEAST (Weld Feasibility Heat Treatment Studies of New Superalloys, registration number: 2019–02787) project funded by the Swedish funding agency VINNOVA.

CC-BY 4.0

The support by the Consortium Materials Technology for Thermal Energy Processes (KME) through funding from Swedish Energy Agency and GKN Aerospace Sweden AB is highly appreciated

This article is licensed under a Creative Commons Attribution 4.0 International License,This work is based on the research within the FEAST (Weld Feasibility Heat Treatment Studies of New Superalloys, registration number: 2019–02787) project funded by the Swedish funding agency VINNOVA.

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries., CC-BY 4.0

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries., CC-BY 4.0

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries., CC-BY 4.0

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries., CC-BY 4.0

Hot cracking susceptibility of Haynes® 282® with varying amount of C (0.05–0.09 wt%), Mn (0.03–0.12 wt%), Si (0.03–0.16), B (0.005–0.006 wt%) and Zr (0–0.01) are investigated. Synergistic role of C and B is found on solidification and heat affected zone (HAZ) liquation cracking susceptibility. High amount of C and B promote formation of eutectic constituents during final stages of solidification and promote crack healing by backfilling effect. When C and B are added in low amount the crack healing does not occur due to the absence of eutectic consituents therefore cracking extent increases. Thermodynamics simulations indicate C and B tie up to MC carbides and M3B2 borides during solidification. Scanning Electron Microscopy and Nanoscale secondary ion mass spectrometry analysis reveal C and B to be present both in solid solution and in form of precipitates to Ti-Mo rich carbides and Mo rich borides, respectively. In HAZ, these phases promote liquation cracking where cracking extent correlates to the amount carbides and borides. Lower C and B is found to reduce the liquation cracking in the HAZ. Furthermore, a high temperature homogenization heat treatment at 1190 °C excarbates the cracking by dissolving the borides and releasing B to the grain boundaries., CC-BY 4.0

Multiple layers of C250 maraging steel were deposited into a single-wall structure by using wire arc additive manufacturing (WAAM). The microstructural characteristics of the as-deposited C250 steel, in terms of solidification structures and phases, were investigated by using optical microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The results show that lath martensite and austenite phases are formed in the as-deposited C250 steel. Apart from these two phases, Laves phase Fe2Ti particles, which have not been reported in C250 steel, are also observed in the C250 steel produced by the WAAM process. TEM analysis does not reveal the formation of strengthening precipitates in the as-built C250 steel, which is further confirmed by hardness measurement., This work was supported by Natural Sciences and Engineering Research Council of Canada.

Understanding the mechanism of microstructural changes caused by isothermal phase transformation reactions in materials plays a vital role in driving the development and effective performance of materials in elevated temperature applications. The kinetics of the phase changes in the microstructure of materials which affect their properties, are often diffusion controlled and a key parameter that is used in the prediction and analysis of diffusion effects is concentration-dependent interdiffusion coefficient, D(C). Existing standard analytical methods of extracting D(C) from experimental concentration profiles such as the Boltzmann-Matano, Sauer-Freise, Wagner, and Hall methods have some flaws, which is a major concern for accuracy and reliability. One of the limitations common to these traditional analytical methods is the assumption on which they are formulated which states that the initial composition profile is a step-function in space. In this study, a new numerical diffusion model, which eliminates non - trivial common assumptions in the literature that degrade accuracy, including the assumption of initial composition profile being a step-function in space, is developed. The new model uses finite element and Galerkin weighted residual methods combined with the Dufort Frankel/Leap Frog explicit scheme and one-dimensional Murray-Landau transformation. The model is successfully validated with previously reported experimental data in the literature and the results obtained show excellent agreement between the model predicted results and experimental data, which confirms the reliability of the new model. The model, which incorporates variable diffusion coefficients and coupled with a recently reported forward simulation technique, can be used to extract the D(C) operative between any two isothermal diffusion times, which is crucial for studying the effect of time on D(C). This is an achievement that is not possible by conventional analytical methods such as the Bolt

Cylindrical parts are widely used in the manufacturing industry, e.g., in making shafts. Such parts are typically machined on lathes by clamping the part on one end and removing material step by step using a cutting tool. The surface quality and dimensional accuracy of machined parts are critical as they directly affect the performance of end products. Structural flexibilities of a cylindrical part clamped on a lathe can lead to unstable vibrations known as chatter. Chatter causes poor surface finish on the part as well as damage to the tool and machine. Chatter can be avoided by proper selection of spindle speed and depth of cut, provided the structural flexibilities of the clamped part are known. However, as a part is machined, we observe changes in the structural dynamics of the part, which means the process parameters, such as spindle speed, must be updated at different stages during machining. This thesis presents a computationally efficient model to update the structural behavior of cylindrical parts during machining. These updated dynamics can then be used to calculate the stability lobe diagrams for each machining step, which leads to optimizing process parameters to maximize manufacturing efficiency. The proposed model is developed using the finite element (FE) method combined with deep learning techniques. First, a finite element model of the initial part is developed numerically, and the associated system matrices are generated and assembled. The removed volumes during the machining stages are then planned and segmented as substructures of the initial part. These substructures are dynamically decoupled from the workpiece by adding the opposite of their dynamics to the initial workpiece. This process updates the frequency response function (FRF) of the workpiece. A complete (full) order finite element model is implemented in the preliminary algorithm. Then, this model is reduced through model order reduction to improve the efficiency of the process by lowe

Transient liquid phase (TLP) bonding has emerged attractive for joining difficult-to-weld advanced materials in a variety of industrial applications. Despite its many advantages, TLP bonding requires relatively long processing time to produce good-quality bonds. In-depth understanding of the underlying mechanisms of TLP bonding is crucial for its optimization. Existing TLP bonding modelling work, for simplicity, mostly consider one-dimensional (1D) migration of the liquid-solid interface. However, the liquid-solid interfaces can practically undergo two-dimensional (2D) or three-dimensional (3D) migration. This work aims to use numerical modelling to study the behavior and kinetics of isothermal solidification during TLP bonding that involve 2D and 3D liquid-solid interface migration. In addition to addressing the complexity of multi-dimensional liquid-solid interface migration, the theoretical model developed in this work conserves solute and does not require the assumption of a concentration-independent solid-state diffusivity by applying a self-adaptive spatial discretization based on the Murray-Landis-Space-Transformation in an explicit-implicit-fusion finite difference modelling approach. Furthermore, in contrast to existing models in the literature, the TLP bonding model for dissimilar materials developed in this work incorporates the occurrence of liquid-state diffusion (LSD) by using a unique adaptation of the upwind/downwind estimation scheme in addition to the simultaneous treatment of the diffusion problems in the single liquid and the solid phases during isothermal solidification. This research shows that aside from the factors that are generally known to determine TLP bonding kinetics, a new factor – the type and degree of curvature of the migrating interfaces – is involved when the interfaces undergo 2D or 3D migration. Additionally, contrary to the general notion based on the Arrhenius relation, it is possible for the concentration-averaged diffusion c

The accuracy of theoretical predictions and analyses of diffusion-controlled phase transformations in materials is significantly influenced by the concentration-dependent interdiffusion coefficient (D(C)). It is generally assumed in the literature that the dependence of the interdiffusion coefficient on concentration is isothermally constant. However, this may not be the case because of the evolution of diffusion stresses and strains, which result from factors that can change the concentration gradients at the same solute concentration. This work aims to theoretically and experimentally study how factors that change concentration gradient and, by implication, the diffusion-induced stress/strain (DIS) influence the solute concentration dependence of the interdiffusion coefficient. In this research work, six factors that are postulated to influence the D(C) have been theoretically studied, and the results are experimentally validated using diffusion couples. The six factors studied are time, temperature, non-uniform initial solute distribution, time-varying surface concentration (SC), solute source concentrations, and diffusion geometry. A theoretical model based on DIS and its relaxation is used to simulate concentration profiles and calculate the D(C). Key theoretical predictions are experimentally verified using a newly developed and validated numerical model to reliably extract the D(C) from experimental data. The theoretical and experimental data analyses show that the concentration dependence of interdiffusion coefficient can significantly change when any of the six factors changes. This study shows that the common practice of using a single interdiffusion coefficient to predict isothermal diffusion effects can become significantly unreliable when the dependence of diffusivity on concentration changes. Neglecting the fundamental concept elucidated in this study can lead to the consequential misidentification of the mechanism of microstructural changes through ph

Diffusion-induced grain boundary migration (DIGM) is the phenomenon of normal grain boundary (GB) migration caused by the lateral diffusion of solutes along with it. Despite its technological importance and the fact that DIGM was first observed and studied since 1970, many aspects are still not fully understood. In this study, molecular dynamics (MD) simulations are used to investigate the physical origins of DIGM with a particular focus on the effects of solute-GB interactions. For this purpose, a few binary alloy systems are deliberately selected, e.g., Al-Ti, Al-Ni, and Ni-Cu, in which strong solute-GB interactions, including solute segregation and anti-segregation, occur. The simulation results show that strong solute segregation and anti-segregation can both influence DIGM. Furthermore, it is shown that the direction of the GB migration dramatically depends on the type of solute-GB interaction, e.g., segregation or anti-segregation, which cause attraction or repulsion between the GB and solute atoms, respectively. It is thus proven that solute-GB interactions play an important role in driving DIGM. Additionally, the driving forces for DIGM can be quantified by combining two atomistic simulation techniques, i.e., the synthetic driving force (SDF) and interface random walk methods. The second part of the study shows that such a solute-induced driving force can be tuned in both type (i.e. attraction or repulsion) and their magnitude by using different solute types (with varying atomic sizes and cohesive energy). These solute types interact with the GB differently, resulting in solute segregation or anti-segregation. Moreover, it is also found that the lattice strain resulting from atomic size mismatch, which has been proposed as an essential driving force for DIGM, is not always needed to induce GB migration. It is also proposed that the non-equilibrium distribution of solute atoms across GB (e.g., one grain being more enriched with solute atoms than the second gr

Transient liquid phase (TLP) bonding has evolved to be an attractive technique for joining difficult-to-weld structural materials. In this study, copper (Cu) substrates are TLP bonded with germanium (Ge) powder to examine the effects of holding time and bonding temperature on the process kinetics. Deviation from parabolic behavior is observed when the width of the isothermal solidification (ISW) is plotted against √t, which is in contrast to what is generally expected. To explain this deviation, a newly developed analytical method is used to calculate the concentration-dependent interdiffusion coefficient, D=F(C) at different holding times and bonding temperatures. In contrast to the common assumption that D=F(C) is an isothermally constant material parameter, the results show that it changes with time, which is attributable to diffusion-induced stress/strain, and this can explain the observed deviation from parabolic behavior. Furthermore, it is observed that for all time durations, the rate of isothermal solidification as well as the concentration-averaged diffusivity, D_ave, reduces as temperature increases from 960ºC to 1040ºC. This observation contradicts what is expected based on the classical Arrhenius relationship where diffusivity increases with temperature. The anomalous behavior observed in this work is attributable to the fact that diffusion coefficient largely increases with concentration and, the concentration range of Ge in Cu reduces with increases in temperature above the Cu-Ge eutectic temperature. In contrast, Arrhenius relationship does not consider the dependence of diffusivity on solute concentration at a given temperature and how the concentration range changes with temperature. Therefore, contrary to general expectations, this study shows that diffusivity can indeed decrease with an increase in temperature during TLP bonding and this can cause prolongation of the time required to complete the process. The experimentally observed reduction in

This paper reviews the latest research progress in the additive manufacturing (AM) process of 18% nickel maraging steels, which involves laser-based powder bed fusion (L-PBF), laser-based directed energy deposition (L-DED), and wire arc additive manufacturing (WAAM). The emphasis is on the defects, structure, and mechanical properties of the additive manufactured 18% nickel maraging steels. At first, this article outlines the influences of the processing parameters of AM techniques on the defects formed in the fabricated parts, in terms of the L-PBF and WAAM. The macrostructure and microstructure characteristics of as-built and heat-treated 18% nickel maraging steel are then described in detail. Later, the mechanical properties of as-built and heat-treated 18% nickel maraging steel are assessed, such as their tensile, hardness, impact toughness, and fatigue performances. Finally, future directions for work on the AM of 18% nickel maraging steel are provided.

Transient liquid phase (TLP) bonding has emerged attractive for joining difficult-to-weld advanced materials in a variety of industrial applications. Despite its many advantages, TLP bonding requires relatively long processing time to produce good-quality bonds. In-depth understanding of the underlying mechanisms of TLP bonding is crucial for its optimization. Existing TLP bonding modelling work, for simplicity, mostly consider one-dimensional (1D) migration of the liquid-solid interface. However, the liquid-solid interfaces can practically undergo two-dimensional (2D) or three-dimensional (3D) migration. This work aims to use numerical modelling to study the behavior and kinetics of isothermal solidification during TLP bonding that involve 2D and 3D liquid-solid interface migration. In addition to addressing the complexity of multi-dimensional liquid-solid interface migration, the theoretical model developed in this work conserves solute and does not require the assumption of a concentration-independent solid-state diffusivity by applying a self-adaptive spatial discretization based on the Murray-Landis-Space-Transformation in an explicit-implicit-fusion finite difference modelling approach. Furthermore, in contrast to existing models in the literature, the TLP bonding model for dissimilar materials developed in this work incorporates the occurrence of liquid-state diffusion (LSD) by using a unique adaptation of the upwind/downwind estimation scheme in addition to the simultaneous treatment of the diffusion problems in the single liquid and the solid phases during isothermal solidification. This research shows that aside from the factors that are generally known to determine TLP bonding kinetics, a new factor – the type and degree of curvature of the migrating interfaces – is involved when the interfaces undergo 2D or 3D migration. Additionally, contrary to the general notion based on the Arrhenius relation, it is possible for the concentration-averaged diffusion c

The accuracy of theoretical predictions and analyses of diffusion-controlled phase transformations in materials is significantly influenced by the concentration-dependent interdiffusion coefficient (D(C)). It is generally assumed in the literature that the dependence of the interdiffusion coefficient on concentration is isothermally constant. However, this may not be the case because of the evolution of diffusion stresses and strains, which result from factors that can change the concentration gradients at the same solute concentration. This work aims to theoretically and experimentally study how factors that change concentration gradient and, by implication, the diffusion-induced stress/strain (DIS) influence the solute concentration dependence of the interdiffusion coefficient. In this research work, six factors that are postulated to influence the D(C) have been theoretically studied, and the results are experimentally validated using diffusion couples. The six factors studied are time, temperature, non-uniform initial solute distribution, time-varying surface concentration (SC), solute source concentrations, and diffusion geometry. A theoretical model based on DIS and its relaxation is used to simulate concentration profiles and calculate the D(C). Key theoretical predictions are experimentally verified using a newly developed and validated numerical model to reliably extract the D(C) from experimental data. The theoretical and experimental data analyses show that the concentration dependence of interdiffusion coefficient can significantly change when any of the six factors changes. This study shows that the common practice of using a single interdiffusion coefficient to predict isothermal diffusion effects can become significantly unreliable when the dependence of diffusivity on concentration changes. Neglecting the fundamental concept elucidated in this study can lead to the consequential misidentification of the mechanism of microstructural changes through ph

Diffusion-induced grain boundary migration (DIGM) is the phenomenon of normal grain boundary (GB) migration caused by the lateral diffusion of solutes along with it. Despite its technological importance and the fact that DIGM was first observed and studied since 1970, many aspects are still not fully understood. In this study, molecular dynamics (MD) simulations are used to investigate the physical origins of DIGM with a particular focus on the effects of solute-GB interactions. For this purpose, a few binary alloy systems are deliberately selected, e.g., Al-Ti, Al-Ni, and Ni-Cu, in which strong solute-GB interactions, including solute segregation and anti-segregation, occur. The simulation results show that strong solute segregation and anti-segregation can both influence DIGM. Furthermore, it is shown that the direction of the GB migration dramatically depends on the type of solute-GB interaction, e.g., segregation or anti-segregation, which cause attraction or repulsion between the GB and solute atoms, respectively. It is thus proven that solute-GB interactions play an important role in driving DIGM. Additionally, the driving forces for DIGM can be quantified by combining two atomistic simulation techniques, i.e., the synthetic driving force (SDF) and interface random walk methods. The second part of the study shows that such a solute-induced driving force can be tuned in both type (i.e. attraction or repulsion) and their magnitude by using different solute types (with varying atomic sizes and cohesive energy). These solute types interact with the GB differently, resulting in solute segregation or anti-segregation. Moreover, it is also found that the lattice strain resulting from atomic size mismatch, which has been proposed as an essential driving force for DIGM, is not always needed to induce GB migration. It is also proposed that the non-equilibrium distribution of solute atoms across GB (e.g., one grain being more enriched with solute atoms than the second gr

Understanding the mechanism of microstructural changes caused by isothermal phase transformation reactions in materials plays a vital role in driving the development and effective performance of materials in elevated temperature applications. The kinetics of the phase changes in the microstructure of materials which affect their properties, are often diffusion controlled and a key parameter that is used in the prediction and analysis of diffusion effects is concentration-dependent interdiffusion coefficient, D(C). Existing standard analytical methods of extracting D(C) from experimental concentration profiles such as the Boltzmann-Matano, Sauer-Freise, Wagner, and Hall methods have some flaws, which is a major concern for accuracy and reliability. One of the limitations common to these traditional analytical methods is the assumption on which they are formulated which states that the initial composition profile is a step-function in space. In this study, a new numerical diffusion model, which eliminates non - trivial common assumptions in the literature that degrade accuracy, including the assumption of initial composition profile being a step-function in space, is developed. The new model uses finite element and Galerkin weighted residual methods combined with the Dufort Frankel/Leap Frog explicit scheme and one-dimensional Murray-Landau transformation. The model is successfully validated with previously reported experimental data in the literature and the results obtained show excellent agreement between the model predicted results and experimental data, which confirms the reliability of the new model. The model, which incorporates variable diffusion coefficients and coupled with a recently reported forward simulation technique, can be used to extract the D(C) operative between any two isothermal diffusion times, which is crucial for studying the effect of time on D(C). This is an achievement that is not possible by conventional analytical methods such as the Bolt

Transient liquid phase (TLP) bonding has evolved to be an attractive technique for joining difficult-to-weld structural materials. In this study, copper (Cu) substrates are TLP bonded with germanium (Ge) powder to examine the effects of holding time and bonding temperature on the process kinetics. Deviation from parabolic behavior is observed when the width of the isothermal solidification (ISW) is plotted against √t, which is in contrast to what is generally expected. To explain this deviation, a newly developed analytical method is used to calculate the concentration-dependent interdiffusion coefficient, D=F(C) at different holding times and bonding temperatures. In contrast to the common assumption that D=F(C) is an isothermally constant material parameter, the results show that it changes with time, which is attributable to diffusion-induced stress/strain, and this can explain the observed deviation from parabolic behavior. Furthermore, it is observed that for all time durations, the rate of isothermal solidification as well as the concentration-averaged diffusivity, D_ave, reduces as temperature increases from 960ºC to 1040ºC. This observation contradicts what is expected based on the classical Arrhenius relationship where diffusivity increases with temperature. The anomalous behavior observed in this work is attributable to the fact that diffusion coefficient largely increases with concentration and, the concentration range of Ge in Cu reduces with increases in temperature above the Cu-Ge eutectic temperature. In contrast, Arrhenius relationship does not consider the dependence of diffusivity on solute concentration at a given temperature and how the concentration range changes with temperature. Therefore, contrary to general expectations, this study shows that diffusivity can indeed decrease with an increase in temperature during TLP bonding and this can cause prolongation of the time required to complete the process. The experimentally observed reduction in

Cylindrical parts are widely used in the manufacturing industry, e.g., in making shafts. Such parts are typically machined on lathes by clamping the part on one end and removing material step by step using a cutting tool. The surface quality and dimensional accuracy of machined parts are critical as they directly affect the performance of end products. Structural flexibilities of a cylindrical part clamped on a lathe can lead to unstable vibrations known as chatter. Chatter causes poor surface finish on the part as well as damage to the tool and machine. Chatter can be avoided by proper selection of spindle speed and depth of cut, provided the structural flexibilities of the clamped part are known. However, as a part is machined, we observe changes in the structural dynamics of the part, which means the process parameters, such as spindle speed, must be updated at different stages during machining. This thesis presents a computationally efficient model to update the structural behavior of cylindrical parts during machining. These updated dynamics can then be used to calculate the stability lobe diagrams for each machining step, which leads to optimizing process parameters to maximize manufacturing efficiency. The proposed model is developed using the finite element (FE) method combined with deep learning techniques. First, a finite element model of the initial part is developed numerically, and the associated system matrices are generated and assembled. The removed volumes during the machining stages are then planned and segmented as substructures of the initial part. These substructures are dynamically decoupled from the workpiece by adding the opposite of their dynamics to the initial workpiece. This process updates the frequency response function (FRF) of the workpiece. A complete (full) order finite element model is implemented in the preliminary algorithm. Then, this model is reduced through model order reduction to improve the efficiency of the process by lowe

Electron beam melting (EBM) produced Alloy 718 was subjected to thermal post-treatment involving hot isostatic pressing (HIPing) and heat treatment (HT). Subjecting the material to HIPing at 1120 degrees C led to significant densification. Study of microstructure evolution during HT (comprising of solution treatment and aging) showed possibility of significantly shortening the HT duration, particularly the time for two-step aging from the standard (8 h + 8 h) long cycle to possibly a shortened (4 h + 1 h) cycle. Another approach for shortening the post-treatment cycle by integrating the HIPing with HT inside the HIP vessel was also successfully implemented. The above observations were further substantiated by tensile response of the material subjected to the varied post-treatment cycles; out of all the post-treatments steps, tensile behaviour was observed to be mainly affected by the aging treatment. Further prospects for shortening the post-treatment protocol are also described, such as shortening of HIPing duration for the typical 4 h to 1 h cycle as well as possible elimination of solution treatment step from the entire post-treatment protocol specifically when prior HIPing is performed. Heat treatment with prior HIPing was found to be crucial for improving fatigue life, because subjecting EBM Alloy 718 to only HT, irrespective of the short or standard long protocol, rendered inferior fatigue response.

Electron beam melting (EBM) produced Alloy 718 was subjected to thermal post-treatment involving hot isostatic pressing (HIPing) and heat treatment (HT). Subjecting the material to HIPing at 1120 degrees C led to significant densification. Study of microstructure evolution during HT (comprising of solution treatment and aging) showed possibility of significantly shortening the HT duration, particularly the time for two-step aging from the standard (8 h + 8 h) long cycle to possibly a shortened (4 h + 1 h) cycle. Another approach for shortening the post-treatment cycle by integrating the HIPing with HT inside the HIP vessel was also successfully implemented. The above observations were further substantiated by tensile response of the material subjected to the varied post-treatment cycles; out of all the post-treatments steps, tensile behaviour was observed to be mainly affected by the aging treatment. Further prospects for shortening the post-treatment protocol are also described, such as shortening of HIPing duration for the typical 4 h to 1 h cycle as well as possible elimination of solution treatment step from the entire post-treatment protocol specifically when prior HIPing is performed. Heat treatment with prior HIPing was found to be crucial for improving fatigue life, because subjecting EBM Alloy 718 to only HT, irrespective of the short or standard long protocol, rendered inferior fatigue response.

Selective laser melting (SLM) is an additive manufacturing (AM) technique used to fabricate patient-specific orthopaedic implants out of highly corrosion resistant alloys such as cobalt–chromium–molybdenum (CoCrMo). Some of the challenges of using AM include parts that are susceptible to porosity, material anisotropy and high residual stresses, which degrade the mechanical properties of the components. However, these issues can be resolved through hot isostatic pressing (HIP). This research aims to investigate the effects of HIP on the corrosion behavior of additive manufactured CoCrMo in phosphate buffered saline (PBS), which is used as a simulated human body fluid, in both normal and inflammatory conditions. An increase in temperature, decrease in pH and introduction of a reactive oxygen species are all characteristics of inflammatory conditions. All of these changes result in an increase in the corrosion rate for both the as-processed additive manufactured and hot isostatic pressed samples. The results of this study also show that the as-processed additive manufactured CoCrMo shows elemental microsegregation, specifically that of Cr. This segregation results in areas that are depleted of Cr, which are then prone to corrosive attacks. HIP reduces the microsegregation in the additive manufactured material, thus increasing the availability of the alloying elements, Cr and Mo, to create a protective passive film which contributes to a higher corrosion resistance as opposed to as-processed CoCrMo in both normal and inflammatory conditions.

Electron beam melting (EBM) produced Alloy 718 was subjected to thermal post-treatment involving hot isostatic pressing (HIPing) and heat treatment (HT). Subjecting the material to HIPing at 1120 degrees C led to significant densification. Study of microstructure evolution during HT (comprising of solution treatment and aging) showed possibility of significantly shortening the HT duration, particularly the time for two-step aging from the standard (8 h + 8 h) long cycle to possibly a shortened (4 h + 1 h) cycle. Another approach for shortening the post-treatment cycle by integrating the HIPing with HT inside the HIP vessel was also successfully implemented. The above observations were further substantiated by tensile response of the material subjected to the varied post-treatment cycles; out of all the post-treatments steps, tensile behaviour was observed to be mainly affected by the aging treatment. Further prospects for shortening the post-treatment protocol are also described, such as shortening of HIPing duration for the typical 4 h to 1 h cycle as well as possible elimination of solution treatment step from the entire post-treatment protocol specifically when prior HIPing is performed. Heat treatment with prior HIPing was found to be crucial for improving fatigue life, because subjecting EBM Alloy 718 to only HT, irrespective of the short or standard long protocol, rendered inferior fatigue response.