Download or read book Electron Beam Melting of Metastable Austenitic Stainless Steel written by Johannes Günther and published by BoD – Books on Demand. This book was released on 2020-01-01 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary focus of this work is the processing – microstructure – property correlation of EBM manufactured high-alloyed austenitic CrMnNi stainless steel. Independent of the applied process parameters, to this point this alloy exhibits a fine-grained and weak textured microstructure in the as-built state upon EBM processing. As detailed in the literature review, this is opposite to numerous alloys like the benchmark AISI 316L stainless steel, which are commonly characterized by epitaxial growth of columnar grains elongated parallel to building direction. A theory for this unusual observation is presented based on a grain refinement due the process-inherent cyclic heat-treatment, i.e. repetitive reheating and partial melting of the consolidated material due to the energy input during melting of subsequent layers and resulting solid-liquid as well as solid-solid (ferritic bcc to austenitic fcc phase and vice versa) phase transformations. A calculation of the phase diagram, differential thermal II Abstract analysis and the investigation of the uppermost layers of bulky and thin-walled EBM processed structures are conducted to support this assumption. Moreover, the CrMnNi stainless steel specimens are characterized by an outstanding damage tolerance, which is demonstrated by tensile testing and examination of the fracture surfaces revealing large lack-of-fusion defects due to unsuitable process parameters. Combined EBSD and X-ray diffraction analysis attribute the high damage tolerance to a pronounced strain hardening and mitigation of the effect of defects due to the transformation-induced plasticity (TRIP) effect. The deformation-induced martensitic transformation and associated strain hardening has also been correlated to a considerable low-cycle fatigue performance even under the presence of large inhomogeneities. The chemical composition of the alloy upon EBM processing is strongly dependent on the process parameters, i.e. it is demonstrated that the evaporation rate of Mn varies with the scan strategy and volumetric energy density. This phenomenon is utilized for the fabrication of homogeneous specimens with different Mn concentrations and resulting mechanical properties.These findings are subsequently employed for a prove-of-concept of the possibility to produce functionally graded material by a spatial adjustment of the scan strategy throughout the layer-wise built-up of objects. This is a novel approach for the synthetization of functionally graded materials based on the processing of one homogenous precursor powder feedstock. In summary, the particular CrMnNi stainless steel is introduced as a novel alloy design for AM because it addresses current material-related issues inherent in layer-wise technologies and potentially further contributes to the exploitation of the full potential of AM.

Download or read book Hot work tool steel in laser powder bed fusion from parameter optimization to quality monitoring in industrial application written by Liang Wu and published by BoD – Books on Demand. This book was released on 2024-01-01 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation thesis focuses on applying the powder bed fusion with laser beam (PBF-LB) technology on hot work steel. It aims at achieving comparable properties with the products from the traditional manufacturing route. Using the reference powder H13, the influence of various factors, i.e., laser settings (such as laser power and scan speed) and machine settings (such as preheating) on the melting pool morphology and printing defects, is intensively investigated to check the feasibility of printing H13 components through PBF-LB technology and finally optimize the fabrication parameters for high-quality printing in lab-scale size. Furthermore, the consecutive research on the impact of the post-treatment, machine sensitivity, and powder condition provides a basis for scaling up the process and offers industrially usable products with adequate properties. Furthermore, after assessing the defects during the investigation, the classification of the defects deepens the understanding of the material-laser interaction. The mechanism for stress-lead cracks can guide the development of new types of material applied to the PBF-LB process, especially carbon-bearing steel. Finally, based on the mechanism of defect generation, the principle of the real-time defect-based monitoring system is proposed. After recognizing defects and assembling discrete points, the digital twin is established from various monitoring signals, which can be applied for on-time quality assurance without destructive testing.

Download or read book Cladded steel for clutch disc carriers written by Hinrich Lührs and published by BoD – Books on Demand. This book was released on 2021-01-01 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Für die Prozessroute von Lamellenträgern können Stahlschichtverbundwerkstoffe, bestehend aus einem duktilem Grundmaterial und einer verschleißfesten Deckschicht, eine kostengünstige Alternative bieten. Im Rahmen der vorliegenden Arbeit wurden die Umformbarkeit, die Verschleißfestigkeit und die Eigenspannungen verschiedener Stahlschichtverbundwerkstoffe betrachtet. Die Umformbarkeit und das Versagensverhalten wurde mittels Biegeversuchen untersucht. Durch in-Situ Biege- und Zugversuche mit anschließender digitaler Bildkorrelation wurden die lokalen Dehnungsverteilungen ermittelt. Das Versagensverhalten wurde anschließend mithilfe einer erweiterten Umformsimulation modelliert. Die Verschleißfestigkeit und die Verschleißmechanismen wurden auf einem Komponentenprüfstand für Lamellenträger untersucht. Mittels Röntgendiffraktometrie wurde der Eigenspannungstiefenverlauf der Stahlschichtverbundwerkstoffe ermittelt.

Download or read book Metals Abstracts written by and published by . This book was released on 1997 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rapidly Solidified Metastable Materials written by B. H. Kear and published by North Holland. This book was released on 1984 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Manganese in Powder Metallurgy Steels written by Andrej Šalak and published by Springer Science & Business Media. This book was released on 2012-07-13 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work in three parts presents a summary of the sintered manganese steel properties from 1948 to 2011 involving processing conditions and other characteristics. In the first and third part are given results attained by the authors based on their finding that manganese (cheapest element) during sintering evaporates and by this the vapour cleans the sintering atmospheres from humidity. The second part presents other positive properties of manganese steels in spite of the doubt of oxidation of manganese during sintering and by this excluding the sintering manganese steels what hinderd the use of manganese in production of sintered parts. All results confirm that only manganese vapour according to finding of the authors ensures effective sintering of manganese steels and parts independently on the authors mind. It follows finally from the work that manganese is possible to use for alloying of powder steels sintered also in practice in H/N atmospheres with low purity and also in pure nitrogen - cheaper than hydrogen without some of the associated problems. Current trends in the field are also presented to the reader.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laser Assisted Forming and Phase Reversal Heat Treatment of Metastable Austenitic Stainless Steel written by Harmen Kooiker and published by . This book was released on 2019 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ISIJ International written by and published by . This book was released on 1991 with total page 900 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications written by United States. National Bureau of Standards and published by . This book was released on 1989 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications of the National Institute of Standards and Technology Catalog written by National Institute of Standards and Technology (U.S.) and published by . This book was released on 1988 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Publications of the National Institute of Standards and Technology 1988 Catalog written by Rebecca J. Pardee and published by . This book was released on 1989 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metals Abstracts Index written by and published by . This book was released on 1996 with total page 1622 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alloy Design and Characterization of Strengthened Nickel based Superalloys for Additive Manufacturing written by Jinghao Xu and published by Linköping University Electronic Press. This book was released on 2021-01-28 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel-based superalloys, an alloy system bases on nickel as the matrix element with the addition of up to 10 more alloying elements including chromium, aluminum, cobalt, tungsten, molybdenum, titanium, and so on. Through the development and improvement of nickel-based superalloys in the past century, they are well proved to show excellent performance at the elevated service temperature. Owing to the combination of extraordinary high-temperature mechanical properties, such as monotonic and cyclic deformation resistance, fatigue crack propagation resistance; and high-temperature chemical properties, such as corrosion and oxidation resistance, phase stability, nickel-based superalloys are widely used in the critical hot-section components in aerospace and energy generation industries. The success of nickel-based superalloy systems attributes to both the well-tailored microstructures with the assistance of carefully doped alloying elements, and the intently developed manufacturing processes. The microstructure of the modern nickel-based superalloys consists of a two-phase configuration: the intermetallic precipitates (Ni,Co)3(Al,Ti,Ta) known as γ′ phase dispersed into the austenite γ matrix, which is firstly introduced in the 1940s. The recently developed additive manufacturing (AM) techniques, acting as the disruptive manufacturing process, offers a new avenue for producing the nickel-based superalloy components with complicated geometries. However, γ′ strengthened nickel-based superalloys always suffer from the micro-cracking during the AM process, which is barely eliminated by the process optimization. On this basis, the new compositions of γ′ strengthened nickel-based superalloy adapted to the AM process are of great interest and significance. This study sought to design novel γ′ strengthened nickel-based superalloys readily for AM process with limited cracking susceptibility, based on the understanding of the cracking mechanisms. A two-parameter model is developed to predict the additive manufacturability for any given composition of a nickel-based superalloy. One materials index is derived from the comparison of the deformation-resistant capacity between dendritic and interdendritic regions, while another index is derived from the difference of heat resistant capacity of these two spaces. By plotting the additive manufacturability diagram, the superalloys family can be categorized into the easy-to-weld, fairly-weldable, and non-weldable regime with the good agreement of the existed knowledge. To design a novel superalloy, a Cr-Co-Mo-W-Al-Ti-Ta-Nb-Fe-Ni alloy family is proposed containing 921,600 composition recipes in total. Through the examination of additive manufacturability, undesired phase formation propensity, and the precipitation fraction, one composition of superalloy, MAD542, out of the 921,600 candidates is selected. Validation of additive manufacturability of MAD542 is carried out by laser powder bed fusion (LPBF). By optimizing the LPBF process parameters, the crack-free MAD542 part is achieved. In addition, the MAD542 superalloy shows great resistance to the post-processing treatment-induced cracking. During the post-processing treatment, extensive annealing twins are promoted to achieve the recrystallization microstructure, ensuring the rapid reduction of stored energy. After ageing treatment, up to 60-65% volume fraction of γ′ precipitates are developed, indicating the huge potential of γ′ formation. Examined by the high-temperature slow strain rate tensile and constant loading creep testing, the MAD542 superalloy shows superior strength than the LPBF processed and hot isostatic pressed plus heat-treated IN738LC superalloy. While the low ductility of MAD542 is existed, which is expected to be improved by modifying the post-processing treatment scenarios and by the adjusting building direction in the following stages of the Ph.D. research. MAD542 superalloy so far shows both good additive manufacturability and mechanical potentials. Additionally, the results in this study will contribute to a novel paradigm for alloy design and encourage more γ′-strengthened nickel-based superalloys tailored for AM processes in the future.

Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1146 pages. Available in PDF, EPUB and Kindle. Book excerpt: