Download or read book Laser Powder Bed Fusion Processed IN713 LC Efforts to Understand Cracking Mechanism Microstructure and Mechanical Properties written by and published by . This book was released on 2020 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Laser Powder Bed Fusion of Metals written by Igor Yadroitsev and published by Elsevier. This book was released on 2021-05-23 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt: Laser powder bed fusion of metals is a technology that makes use of a laser beam to selectively melt metal powder layer-by-layer in order to fabricate complex geometries in high performance materials. The technology is currently transforming aerospace and biomedical manufacturing and its adoption is widening into other industries as well, including automotive, energy, and traditional manufacturing. With an increase in design freedom brought to bear by additive manufacturing, new opportunities are emerging for designs not possible previously and in material systems that now provide sufficient performance to be qualified in end-use mission-critical applications. After decades of research and development, laser powder bed fusion is now enabling a new era of digitally driven manufacturing. Fundamentals of Laser Powder Bed Fusion of Metals will provide the fundamental principles in a broad range of topics relating to metal laser powder bed fusion. The target audience includes new users, focusing on graduate and undergraduate students; however, this book can also serve as a reference for experienced users as well, including senior researchers and engineers in industry. The current best practices are discussed in detail, as well as the limitations, challenges, and potential research and commercial opportunities moving forward. - Presents laser powder bed fusion fundamentals, as well as their inherent challenges - Provides an up-to-date summary of this advancing technology and its potential - Provides a comprehensive textbook for universities, as well as a reference for industry - Acts as quick-reference guide

Download or read book Pulse Laser Powder Bed Fusion of High Strength Aluminum Alloys written by Andrew Walker and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This work presents the foundation and results of a study of the pulse laser powder bed fusion process (P-LPBF). It focuses on the unique opportunity offered for the additive manufacturing (AM) industry to control the microstructure and mechanical properties of high strength aluminum alloys.A literature review has been presented covering the topics; additive manufacturing, high strength aluminum alloys, solidification physics, and evaporation phenomena. The work goes on to present results of a P-LPBF processing study of Al-Zn-Mg-Cu and Al-Mg-Si alloys. It was found that as built specimens of 98.0±0.5 Vol% density were achievable for the Al-Zn-Mg-Cu alloy, whereas samples with 99.3±0.4 Vol% density were produced from the Al-Mg-Si alloy.Solidification microstructures were examined and found to present highly refined second phases with coarse melt pool regions for both alloys. Quantitative analysis of the solidification behaviour of the Al-Zn-Mg-Cu alloy was conducted with the CGM and KGT microstructure development models. It was concluded that neither alloy exhibited significant departure from equilibrium solidification behaviour. The bulk chemical analyses of P-LPBF specimens of each alloy indicated that significant solute loss had occurred. Standard T6 heat treatment procedures were applied to the samples, yielding the expected microstructure and hardness results. The observed hardness of the Al-Zn-Mg-Cu alloy samples were found to fall below the wrought material while Al-Mg-Si alloy samples were able to slightly exceed the wrought properties. Solute loss was identified as the main variable driving this phenomenon. The AA7175 composition was more sensitive to solute loss as it depended more heavily on precipitation strengthening, while AA6061 made significant use of the Hall-Petch hardening mechanism, allowing it to tolerate substantial solute loss while maintaining the desired mechanical properties.In summary, this work has investigated the microstructural, mechanical, and chemical properties of two solidification crack susceptible aluminum alloys. The findings clearly demonstrate promising results for the feasibility of P-LPBF AM processing of high strength aluminium alloys." --

Download or read book Laser Powder Bed Fusion of Precipitation hardened Rene 41 and Rene 77 Nickel Base Superalloys written by Sila Atabay and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser powder bed fusion (LPBF) is a promising technology that enables production of complex parts with unique freedom in design and short lead times. For applications requiring high strength and high temperature resistance, Ni-base superalloys are the primary choice of materials. Although variety of superalloys can be produced through LPBF, most high strength alloys are prone to cracking and considered difficult to weld. The main objective of this research is to assess the processability of precipitation hardenable Ni-base superalloys by LPBF. For this purpose, processing of two different precipitation hardenable alloys, Rene 41 (R41) having a fair weldability and Rene 77 (R77) categorized as difficult to weld, are studied along with their microstructural development and mechanical properties. First, R41 alloy was produced by LPBF, and its microstructural evolution was investigated. Crack-free, dense samples were produced upon parameter optimization. The as-built (AB) microstructure revealed columnar grains with a preferred orientation along 100 direction. [gamma]' precipitation was suppressed due to high cooling rates in LPBF. Afterwards, the samples were subjected to the standard heat treatment (HT). Even though the grain morphology was similar to the AB sample, formation of carbide particles was observed along with the precipitation of [gamma]' after the HT. Mechanical properties of the samples both in AB and HT state was characterized. Results proved that when standard HT is applied to the LPBF fabricated R41 parts, the measured room temperature (RT) strength and elongation meet the AMS specifications. Effect of build direction on the mechanical properties was also studied. Since the microstructure obtained after LPBF is very different compared to the conventional processing techniques, suitability of the commercially applied HT cycles has to be studied. Hence, additional HTs were applied to understand the effect of different solutionizing temperatures on the development of microstructure and mechanical properties. Detailed microstructural analysis were conducted after each HT. These analyses revealed that for HT above the [gamma]' solvus temperature, resulted in the precipitation of [gamma]' and carbide phases similarly to the sub-solvus HT but with a different size distribution and morphology. However, formation of an equiaxed grain morphology with random orientation was detected. Furthermore, tensile properties were tested at 760°C. YS and UTS values obtained for AB, sub-solvus and super-solvus HT samples were on par with the wrought and HT alloys reported in literature. However, the measured elongation and deformation behaviors showed significant differences. The columnar grain morphology of the sub-solvus HT sample led to the highest elongation while the microstructure obtained after super-solvus treatment had the highest work hardening rate during deformation. Finally, the knowledge gained from R41 was used to study the manufacturability of the R77 alloy. This alloy is more prone to cracking during fabrication due to its higher content of alloying elements. Elimination of cracking in a difficult to weld alloy solely by parameter optimization was proven possible with LPBF of R77. Furthermore, these crack-free structures were maintained upon a modified version of the standard HT. Detailed microstructural characterization of AB and HT samples were conducted similarly to the R41. In this case, presence of extremely fine [gamma]' precipitates were identified after LPBF, and a bimodal distribution of precipitates was developed following the HT. Tensile properties for both conditions were tested at RT and 810 °C and the results were compared with wrought counterparts and with other difficult to weld alloys fabricated by LPBF. The deformation behavior of the samples in both conditions changed with the temperature. AB sample showed significant hardening whereas, the HT one had improved elongation due to thermally activated microtwinning"--

Download or read book Laser Powder Bed Fusion of 316L Stainless Steel written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Qualification of a Ni Cu Alloy for the Laser Powder Bed Fusion Process LPBF written by Iris Raffeis and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book LASER POWDER BED FUSION OF Ti 6Al 2Sn 4Zr 2Mo 0 08Si Ti 6242 ALLOY PROCESS MICROSTRUCTURE PROPERTIES RELATIONSHIP written by Harish Chandra Kaushik and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The current work is focused on Laser-powder bed fusion (L-PBF) of Ti-6Al-2Sn-4Zr-2Mo-0.08Si (Ti-6242) which is a near-Îł titanium alloy used for high-temperature applications. The fabrication of Ti-6242 is common using conventional techniques such as casting, forging, and powder metallurgy whereas the L-PBF of Ti-6242 is comparatively new. This offers the opportunity to develop the process-microstructure-property relationship of Ti-6242 fabricated through L-PBF. This includes tasks like 3D printing of Ti-6242 followed by the study of mechanical properties and the governing microstructures of as-built (AB) and after post-processing (heat treatment in this case). In the current study, the 3D printing of Ti-6242 was done by varying the volumetric energy density (E_v) from 41.67 to 66.67 J/mm3 by changing the scanning speeds. The variation in E_v results in variation in mechanical properties. Both the microstructure and defect analysis are performed. The defect characteristics are changed from keyhole to lack of fusion by varying the E_v from high to low whereas the microstructural characteristics are almost consistent. This concluded that the changes in mechanical properties of laser-powder bed fused Ti-6242 (L-PBF-Ti-6242) are defect-driven rather than microstructure-driven in the AB condition. The sample fabricated with process parameters offering the best combination of strength and ductility is selected for further studies. The systematic study of L-PBF-Ti-6242 is further proceeded by investigating the kinetics of Îł to Îø phase transformation using differential scanning calorimetry (DSC). Both non-isothermal and isothermal kinetics models are developed using the DSC results and employing the Johnson-Mehl-Avrami-Kolmogorov equation. As the AB microstructure of L-PBF-Ti-6242 consists of Îł0́9 martensite which is a brittle constituent it shows high strength and low ductility. To achieve the strength-ductility synergy, the modeled Îł to Îø phase transformation kinetics is used to design and develop two-step (solutionizing and aging) post-process heat treatment with an emphasis on preserving the unique, ultrafine, and hierarchical microstructure. The solutionized microstructure, 900℗ʻC for 10 minutes (S), has Îł/Îł0́9 and Îø phases with different dislocation densities. This condition results in the lowest strength and highest ductility, governed by the presence of the bcc phase (Îø), and high mean effective slip length in the Îł/Îł0́9 phase. The aging process, 300℗ʻC for 48 hours following the solutionizing step (STA) results in changes in dislocation substructure in the Îł/Îł0́9 phase which leads to an increase in strength, controlled by a reduction in mean effective slip length. The formulated two-step heat treatment leads to the best strength-ductility synergy in this study. The high-temperature mechanical property of L-PBF-Ti-6242 was investigated for AB, S, and STA conditions. In the AB condition, the LPBF-Ti-6242 shows superior strength at high temperatures in comparison with Ti-6Al-4V. In the case of L-PBF-Ti-6242, although the STA shows superior strength at room temperature, both S and STA exhibit almost similar strength at high temperatures. It is proposed that the developed heat treatment recipe attained a better combination of strength and ductility at room as well as high temperature. This justified the importance of the study of phase transformation kinetics to develop the heat treatment recipe for titanium alloys newly fabricated through L-PBF.

Download or read book Laser Powder Bed Fusion Processing of Aluminum Powders Containing Iron and Nickel written by Jonathan Hierlihy and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The variety of aluminum alloys currently used in laser powder bed fusion additive manufacturing (PBF-AM) is limited, yet the demand for such materials is growing. The AM community is particularly keen on aluminum alloys that offer enhanced thermal stability. Traditionally, this trait has been instilled through transition metal additions that form stable aluminides. This project seeks to devise new PBF-AM materials in this context starting with a precursory study into the effects of iron and nickel additions. Here, gas atomized Al-1Fe and Al-1Ni (wt.%) powders were processed via PBF-AM over a range of volumetric energy densities achieved through systematic adjustments to laser power, scan speed, and hatch spacing. The microstructure (OM, SEM, EDS, XRD) and physical properties (hardness, density, surface roughness) of the products were characterized. Results indicated that Al-1Fe was more responsive to processing as it densified to 99.0% of full theoretical and had a hardness of 95 HRH. Conversely, Al-1Ni only reached 97.8% theoretical density and a peak hardness of 78 HRH. It was also more prone to solidification cracking. Energy density values of at least 32.5 J mm-3 were necessary to achieve peak density and hardness.

Download or read book Novel Processing Strategies for Laser Powder Bed Fusion to Reduce Defects in High Temperature TZM Alloy written by James Hanagan and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: TZM is a high temperature molybdenum alloy that is of interest for aerospace, nuclear power, and medicine, and additive manufacturing (AM) offers the ability to generate novel designs for these applications, but there is little in the literature that investigates AM of TZM. In this work, the ability of TZM to be processed via laser powder bed fusion (LPBF) is investigated. Novel laser processing parameters, including double exposure of every layer and shorter hatch lengths, are utilized to influence melt pool morphology and solidification in attempting to create a defect free microstructure without the need to heat the build substrate to extreme temperatures. For each type of process strategy used, a variety of combinations for laser power, scan speed, and hatch spacing are tested. In addition, a novel specimen geometry is utilized to test the limits of TZM for processing fine features and support structures. With this set of laser parameters, relative densities as high as 99.76% and microhardness values as high as 400 HV are achieved. It is determined that the double exposure processing strategy is not shown to be effective as a method of processing TZM due to high defect quantities in the microstructure and high rate of build failures (e.g. due to cracking and distortion) among those specimens. Short hatch lengths, on the other hand, prove to be quite effective with 100% of specimens using a laser scan speed of 600 mm/s being built successfully to completion. These specimens had similar microstructures to the normal exposure specimens, so as a result it appears that hatch lengths anywhere from 0.5 mm to 5 mm showed potential for further optimization. Ultimately, this work shows that LPBF of TZM without high build substrate heating holds promise for producing TZM structures with minimal defects and limited cracking.

Download or read book Novel Fabrication of Alloy 625 and MCrAlY Bond Coat by Laser Powder Bed Fusion and Microstructure Control written by Jiwon Lee and published by . This book was released on 2020 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, Alloy 625 was fabricated by one of the most commonly used additive manufacturing (AM) methods, laser powder bed fusion (L-PBF), and its mechanical properties were evaluated at various temperatures. The L-PBF fabricated Alloy 625 showed high strength and relatively poor elongation. Thus, some heat treatments were applied to improve its performance. A solid-solution heat treatment with a temperature of more than 1000 °C was applied to the L-PBF Alloy 625, resulting in recrystallization because of high energy stored within the alloy attributed by high density of dislocations. This modified microstructure of the L-PBF Alloy 625 sample showed the required strength under tensile testing at room temperature (higher strength than wrought Alloy 625 and greater elongation than L-PBF as-built alloy). In view of enhancing mechanical properties at high temperature, a grain boundary serration (GBS) heat treatment was specifically designed for L-PBF Alloy 625. Because this was the first attempt to produce GBS in a high-Nb-content alloy, it was necessary to understand its mechanism first. To induce GBS, it is necessary for large solute atoms to move near the grain boundaries (GBs). Therefore, the GBS heat treatment was modified for application to the L-PBF Alloy 625. The specially designed GBS heat treatment successfully induced the zigzag patterns of serrated GBs for the first time. This GBS L-PBF Alloy 625 showed improved high-temperature mechanical properties in terms of increased ductility and elimination of the dynamic strain aging (DSA) effect at elevated temperatures. To further improve the high-temperature property of the L-PBF Alloy 625, NiCrAlY bond coat was applied to the Alloy 625 substrate by the same method (L-PBF) for the first time to improve the efficiency of the production process and increase the resistance to oxidation. Although their different thermal properties led to many trials and errors in the manufacturing of the material, the optimal parameters for applying NiCrAlY bond coat deposition by L-PBF were set and verified to assess the potential for the process to be commercialized. The remelting characteristic of L-PBF induced good metallurgical bonding between the substrate and coating, which indicates good stability. The oxidation behavior of the NiCrAlY-coated Alloy 625 was characterized by thermal gravimetric analysis (TGA) and thermal shock testing; the results indicated that the novel coated material had higher resistance to oxidation than bulk Alloy 625. Therefore, the GBS heat treatment together with efficient NiCrAlY coating can greatly improve the high-temperature mechanical properties of L-PBF manufactured Alloy 625.

Download or read book Relationship Between Porosity and Mechanical Properties in Laser Powder Bed Fusion Fabricated Ti6Al4V Alloy written by Flavio Weinstein Silva and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser Powder Bed Fusion (LPBF) is an Additive Manufacturing (AM) process that offers superior versatility and direct part manufacturing from Computer Aided Design (CAD) model. It provides nearly unrestricted freedom to design in order to optimize part functionality producing shapes that would be impossible with conventional manufacturing such as moulding or machining. Moreover, it has a very low buy-to-fly ratio offering savings in material usage and lower waste from machining.Despite all the ground-breaking benefits mentioned, porosity is currently an inevitable process-induced defect commonly found in as-fabricated LPBF components. Porosity level as low as 0.5% contained in manufactured parts can still render them unfit for large-scale structural applications, such as in aerospace, due to its negative effects on mechanical properties. As an effective time and cost saving approach for assessing different types of pores for quality control and catastrophic failure prevention, the use of Finite Element Analysis (FEA) was proposed. By modelling the pores found in the parts' microstructure, a threshold is expected to be determined on the tolerable defect amount to be allowed while still preserving the minimum mechanical property required for a given application.The results found in this thesis presents a methodology for assessing the types of pores and pore clusters found in LPBF Ti-6Al-4V manufactured parts. The concept of stress triaxiality was used as a parameter and failure criteria for pore evaluation and damage initiation, respectively. This parameter enabled so far to obtain a trend with respect to the pore morphology and describe the dominant mechanism of failure pertaining this type of defect found in LPBF parts. Moreover, pore morphology and directionality simulated in FEA were found to significantly influence strain limit to fracture initiation showing a more premature failure mode for pores with smaller radius of curvature and directionally perpendicular to tensile load direction." --

Download or read book Laser Powder Bed Fusion of beta 21S Titanium Alloy written by Maria Macias Sifuentes and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Laser powder bed fusion (LPBF), one of the most studied processes among metal additive manufacturing (AM), has raised attention due to its high degree of manufacturing freedom, its ability to produce lightweight intricate components, and its energy-efficient, and time saving route. Today, research has focused only on a limited number of alloys such as Ti-6Al-4V, Inconel 625 and 718, and stainless steel 316L. New alloys produced by this technique need to be studied to be able to maximize the advantages of AM. Metastable [beta]-titanium alloys are attractive for the aerospace industry due to their low density, high strength, excellent hardenability, and stability at high temperature. Among these alloys, [beta]-21S is known to offer improved elevated temperature strength, creep resistance, thermal stability, and oxidation resistance. Furthermore, heat treatment can be applied to this alloy for tailoring the mechanical properties according to the desired application. The manufacturability of [beta]-21S produced by LPBF, as well as the effect of heat treatment was investigated in the present thesis, to understand the relationship between the microstructure and the mechanical properties. The tensile performance of [beta]-21S in the as-built state presented comparable behavior to the wrought in solution treatment condition. Solution treatment and aging (STA) of the alloy precipitated the [alpha]-phase, increasing the microhardness, and strength, while reducing the ductility. The heat treatment applied to LPBF [beta]-21S had a similar effect compared to [beta]-21S fabricated by non-AM techniques. The properties obtained demonstrated the potential of [beta]-21S for LPBF applications"--

Download or read book Analysis of the Laser Powder Bed Fusion Additive Manufacturing Process Through Experimental Measurement and Finite Element Modeling written by Alexander Dunbar and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective in this work is to provide rigourous experimental measurements to aid in the development of laser powder bed fusion (LPBF) additive manufacturing (AM). A specialized enclosed instrumented measurement system is designed to provide in situ experimental measurements of temperature and distortion. Experiments include comparisons of process parameters, materials and LPBF machines. In situ measurements of distortion and temperature made throughout the build process highlight inter-layer distortion effects previously undocumented for laser powder bed fusion. Results from these experiments are also be implemented in the development and validation of finite element models of the powder bed build process. Experimental analysis is extended from small-scale to larger part-scale builds where experimental post-build measurements are used in analysis of distortion profiles. Experimental results provided from this study are utilized in the validation of a finite element model capable of simulating production scale parts. The validated finite element model is then implemented in the analysis of the part to provide information regarding the distortion evolution process. A combination of experimental measurements and simulation results are used to identify the mechanism that results in the measured distortion profile for this geometry. Optimization of support structure primarily focuses on the minimization of material use and scan time, but no information regarding failure criteria for support structure is available. Tensile test samples of LPBF built support structure are designed, built, and tested to provide measurements of mechanical properties of the support structure. Experimental tests show that LPBF built support structure has only 30-40\% of the ultimate tensile strength of solid material built in the same machine. Experimental measurement of LPBF built support structure provides clear failure criteria to be utilized in the future design and implementation of support structure.

Download or read book An Empirical Approach for the Development of Process Parameters for Laser Powder Bed Fusion written by Aron Pfaff and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: For certain additive manufacturing technologies the choice of available materials is currently limited. The development of process parameters is especially elaborate for powder bed technologies. Currently, there is no common approach concerning the procedure and documentation. This work proposes a methodology for the initial development of process parameters for new L-PBF (laser powder bed fusion) alloys. Key elements are the examination of the laser-powder-bed interaction by single laser track experiments and an iterative design of experiment (DoE) approach for the development of volumetric parameters. Two types of single laser track experiments are presented and provide information regarding the laser track width and depth as well as the resulting surface roughness and melt pool classification. Based on the information gained, suitable process windows for a DoE study can be defined by avoiding parameter settings unsuitable for production or measurement. Gradually, input variables are identified and iterative steps reduce the process window in order to optimize the desired target values. Near-surface exposure parameters are developed by a one-dimensional parameter variation and metallographic investigations. The approach is primarily designed for the initial development of process parameters for new L-PBF alloys. However, the information gained can also be used to optimize established parameter sets regarding new target values (productivity, mechanical properties), optimize process parameters for specific components or for a microstructural design

Download or read book Laser Powder Bed Fusion Processing and Heat Treatment of Ni base Superalloys written by Abdul Shaafi Shaikh and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Processability of Laser Powder Bed Fusion of Alloy 247LC written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Processability of Laser Powder Bed Fusion of Alloy 247LC Influence of Process Parameters on Microstructure and Defects written by Olutayo Adegoke and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: