Endre søk
Begrens søket
1 - 13 of 13
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Asala, G.
    et al.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Khan, A. K.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik. Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, O. A.
    University of Manitoba, Department of Mechanical Engineering, Winnipeg, Canada.
    Microstructural Analyses of ATI 718Plus® Produced by Wire-ARC Additive Manufacturing Process2017Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, nr 9, s. 4211-4228Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed microstructural study of ATI 718Plus superalloy produced by the wire-arc additive manufacturing (WAAM) process was performed through the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe micro-analysis (EPMA), and electron backscatter diffraction (EBSD). Extensive formation of eutectic solidification microconstituents including Laves and MC-type carbide phases, induced by micro-segregation, are observed in the build of the alloy in the as-deposited condition. Notwithstanding the significant segregation of niobium (Nb), which has been reported to promote the formation of the delta-phase in ATI 718Plus, only eta-phase particles are observed in the deposit. Excessive precipitation of eta-phase particles is found to be linked to Laves phase particles that are partially dissolved in the deposit after post-deposition heat treatment (PDHT). The EBSD analysis shows a high textured build in the aOE (c) 100 > directions with only a few misoriented grains at the substrate-deposit boundary and the top of the deposit. Investigation on the hardness of the build of the alloy, in the as-deposited condition, showed a softened zone about 2 mm wide at the deposited metal heat affected zone (DMHAZ), which has not been previously reported and potentially damaging to the mechanical properties. An extensive analysis with the use of both microstructural characterization tools and theoretical calculations shows that the DMHAZ has the lowest volume fraction of strengthening precipitates (gamma’ and gamma aEuro(3)) in terms of their number density, which therefore induces the observed softness. Delayed re-precipitation kinetics and the extent of the precipitation of gamma’ and gamma aEuro(3) in the DMHAZ which is related to the diffusion of segregated solute elements from the interdendritic regions are attributed to this phenomenon. The microstructural analyses discussed in this work are vital to adequate understanding of properties of ATI 718Plus produced by the additive manufacturing process technique.

  • 2. Das, D. K.
    et al.
    Singh, V.
    Joshi, S. V.
    Effect of prealuminizing diffusion treatment on microstructural evolution of high-activity pt-aluminide coatings2000Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 31, nr 8, s. 2037-2047Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of prealuminizing (or prior) diffusion treatment on the evolution of Pt-aluminide coatings on the Ni-based superalloy CM-247 has been studied by using a single-step, high-activity aluminizing process. Coatings generated without any prior diffusion treatment, as well as those formed by adopting two extreme prior-diffusion schedules (at 850 °C for 0.5 hours and at 1034 °C for 5 hours), were investigated by analyzing the coating structures at various stages of aluminizing. When the dilution of the Pt layer, caused by its interdiffusion with the substrate during the prior diffusion treatment, is only marginal (as in the case of no prior diffusion and diffusion at 850 °C for 0.5 hours), the equilibrium Pt-aluminide coating structure evolves through the formation of two transient layers during the initial stages of aluminizing. In contrast, for diffusion at 1034 °C for 5 hours, which results in extensive dilution of the Pt layer, the two-phase equilibrium structure (PtAl2 in a matrix of NiAl) in the outer layer of the coating is found to develop during very early stages of aluminizing and remains unchanged, even over extended periods of aluminizing. Further, in the case of prior diffusion at 1034 °C for 5 hours, Pt is found to remain distributed to a greater extent over the entire thickness of the coating than in the cases of limited prior diffusion treatment. The present findings underline the significance of the nature of the prior-diffusion schedule on the microstructural evolution of Pt-aluminide coatings. It has also been found that a prealuminizing diffusion treatment is particularly important for Pt-aluminide coatings from the point of view of coating adhesion to the substrate.

  • 3.
    Eriksson, Erik
    et al.
    Department of Physics, Chalmers University of Technology, Gothenburg (SWE).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Hörnqvist Colliander, M.
    Department of Physics, Chalmers University of Technology, Gothenburg (SWE).
    The Effect of Grain Boundary Carbides on Dynamic Recrystallization During Hot Compression of Ni-Based Superalloy Haynes 282 TM2021Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In alloys where carbides are the main grain boundary phase, the role of carbides during hot working is not known. Here, we address the effect of grain boundary carbides on the dynamic recrystallization during hot compression of Ni-base superalloy Haynes 282. When excluding variations from experimental factors neither stress evolution nor final microstructure indicated that carbides exerted a significant influence on the dynamic recrystallization. The carbide solvus temperature is not a critical limit during thermomechanical processes.

    Fulltekst (pdf)
    Springer
  • 4.
    Goel, Sneha
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Mehtani, Hitesh
    Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, India (IND).
    Yao, Shu-Wei
    Xi’an Jiaotong University, School of Materials Science and Engineering, Xi’an, 710049, China (CHN).
    Samajdar, Indradev
    Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai, 400076, India (IND).
    Klement, Uta
    Chalmers University of Technology, Gothenburg, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    As-Built and Post-treated Microstructures of an Electron Beam Melting (EBM) Produced Nickel-Based Superalloy2020Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 51, nr 12, s. 6546-6559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The microstructures of an electron beam melted (EBM) nickel-based superalloy (Alloy 718) were comprehensively investigated in as-built and post-treated conditions, with particular focus individually on the contour (outer periphery) and hatch (core) regions of the build. The hatch region exhibited columnar grains with strong texture in the build direction, while the contour region had a mix of columnar and equiaxed grains, with no preferred crystallographic texture. Both regions exhibited nearly identical hardness and carbide content. However, the contour region showed a higher number density of fine carbides compared to the hatch. The as-built material was subjected to two distinct post-treatments: (1) hot isostatic pressing (HIP) and (2) HIP plus heat treatment (HIP + HT), with the latter carried out as a single cycle inside the HIP vessel. Both post-treatments resulted in nearly an order of magnitude decrease in defect content in hatch and contour regions. HIP + HT led to grain coarsening in the contour, but did not alter the microstructure in the hatch region. Different factors that may be responsible for grain growth, such as grain size, grain orientation, grain boundary curvature and secondary phase particles, are discussed. The differences in carbide sizes in the hatch and contour regions appeared to decrease after post-treatment. After HIP + HT, similar higher hardness was observed in both the hatch and contour regions compared to the as-built material.

  • 5.
    Hosseini, Vahid
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Innovatum AB Trollhättan,Trollhättan,Sweden.
    Thuvander, Mattias
    Chalmers University of Technology, Department of Physics, Gothenburg,Sweden.
    Wessman, Sten
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Spinodal Decomposition in Functionally Graded Super Duplex Stainless Steel and Weld Metal2018Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, nr 7, s. 2803-2816Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low-temperature phase separations (T < 500 °C), resulting in changes in mechanical and corrosion properties, of super duplex stainless steel (SDSS) base and weld metals were investigated for short heat treatment times (0.5 to 600 minutes). A novel heat treatment technique, where a stationary arc produces a steady state temperature gradient for selected times, was employed to fabricate functionally graded materials. Three different initial material conditions including 2507 SDSS, remelted 2507 SDSS, and 2509 SDSS weld metal were investigated. Selective etching of ferrite significantly decreased in regions heat treated at 435 °C to 480 °C already after 3 minutes due to rapid phase separations. Atom probe tomography results revealed spinodal decomposition of ferrite and precipitation of Cu particles. Microhardness mapping showed that as-welded microstructure and/or higher Ni content accelerated decomposition. The arc heat treatment technique combined with microhardness mapping and electrolytical etching was found to be a successful approach to evaluate kinetics of low-temperature phase separations in SDSS, particularly at its earlier stages. A time-temperature transformation diagram was proposed showing the kinetics of 475 °C-embrittlement in 2507 SDSS.

    Fulltekst (pdf)
    fulltext
  • 6. Kjellsson, Henrik
    et al.
    Balachandramurthi, Arun Ramanathan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Moverare, Johan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Department of Management and Engineering, Linköping University, 58183, Linköping (SWE).
    Hansson, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    High Temperature Fatigue Performance of Electron Beam Powder Bed Fusion Manufactured Alloy 7182022Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 53, s. 2496-2514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The microstructure and mechanical properties of additively manufactured (AM) parts have been shown to be different from that of cast and wrought counterparts. In this study, electron beam powder bed fusion (EB-PBF) fabricated Alloy 718 was exposed to three different heat treatment routes followed by strain-controlled fatigue testing at 550 degrees C. The fatigue tests were performed with specimens built with their center axis parallel and transverse relative to the build direction. The microstructure showed saturated precipitation of delta-Ni3Nb after repeated solution treatment at 954 degrees C. In contrast, no delta-Ni3Nb precipitates could be observed after a single-step solution treatment at 1025 degrees C. However, the disparity of secondary phases showed no noticeable influence on the fatigue life. A significant difference in fatigue behavior was noted between the parallel and transverse directions. The specimens loaded parallel to the elongated grains showed on average similar to 5x greater life in comparison to the perpendicularly loaded specimens. Compared to corresponding heat-treated material conditions tested at ambient temperature, the specimens showed lower life at high strain amplitude and superior life at low strain amplitude. Moreover, competitive internal and surface failure modes were observed at the lower strain amplitudes while for the higher strain ranges, surface failure modes dominated. (C) The Author(s) 2022

    Fulltekst (pdf)
    fulltext
  • 7.
    Kumara, Chamara
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Deng, Dunyong
    Linköping University, Division of Engineering Materials, Department of Management and Engineering, Linköping, 58183, Sweden.
    Hanning, Fabian
    Chalmers University of Technology, Department of Industrial and Materials Science, Göteborg, 412 96, Sweden.
    Raanes, Morten
    NTNU, Department of Materials Science and Engineering, IMA, Alfred Getz vei 2, Trondheim, 7491, Norway.
    Moverare, Johan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Linköping University, Division of Engineering Materials, Department of Management and Engineering, Linköping, 58183, Sweden.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Predicting the Microstructural Evolution of Electron Beam Melting of Alloy 718 with Phase-Field Modeling2019Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50A, nr 5, s. 2527-2537Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electron beam melting (EBM) is a powder bed additive manufacturing process where a powder material is melted selectively in a layer-by-layer approach using an electron beam. EBM has some unique features during the manufacture of components with high-performance superalloys that are commonly used in gas turbines such as Alloy 718. EBM has a high deposition rate due to its high beam energy and speed, comparatively low residual stresses, and limited problems with oxidation. However, due to the layer-by-layer melting approach and high powder bed temperature, the as-built EBM Alloy 718 exhibits a microstructural gradient starting from the top of the sample. In this study, we conducted modeling to obtain a deeper understanding of microstructural development during EBM and the homogenization that occurs during manufacturing with Alloy 718. A multicomponent phase-field modeling approach was combined with transformation kinetic modeling to predict the microstructural gradient and the results were compared with experimental observations. In particular, we investigated the segregation of elements during solidification and the subsequent "in situ" homogenization heat treatment at the elevated powder bed temperature. The predicted elemental composition was then used for thermodynamic modeling to predict the changes in the continuous cooling transformation and time-temperature transformation diagrams for Alloy 718, which helped to explain the observed phase evolution within the microstructure. The results indicate that the proposed approach can be employed as a valuable tool for understanding processes and for process development, including post-heat treatments. © 2019, The Author(s).

  • 8.
    Rakoczy, Lukasz
    et al.
    Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Kraków (POL).
    Grudzien-Rakoczy, Malgorzata
    Lukasiewicz Research Network-Krakow Institute of Technology Kraków (POL).
    Hanning, Fabian
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Cempura, Grzegorz
    Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Kraków (POL).
    Cygan, Rafal
    Investment Casting Division, Consolidated Precision Products Corporation, Rzeszow (POL).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Zielinska-Lipiec, Anna
    Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology,Kraków (POL).
    Investigation of the y´ Precipitates Dissolution in a Ni-Based Superalloy During Stress-Free Short-Term Annealing at High Homologous Temperatures2021Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 52, nr 11, s. 4767-4784Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The equiaxed Ni-based superalloy Rene 108 was subjected to short-term annealing at five temperatures between 900 degrees C and 1100 degrees C. The phase composition, phase lattice parameters, microstructure, stereological parameters, and chemical composition of y´ precipitates were investigated by thermodynamic simulations, X-ray diffraction, scanning and transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Analysis of the y and y´ lattice parameters using the Nelson-Riley extrapolation function showed that the misfit parameter for temperatures 900 degrees C to 1050 degrees C is positive (decreasing from 0.32 to 0.11 pct). At 1100 degrees C, the parameter becomes negative, delta = - 0.18 pct. During the short-term annealing, gamma ‘ precipitates dissolution occurred progressing more rapidly with increasing temperatures. The surface fraction of y´ precipitates decreased with increasing temperature from 0.52 to 0.34. The dissolution of gamma ‘ precipitates did not only proceed through uninterrupted thinning of each individual precipitate, but also included more complex mechanisms, including splitting. Based on transmission electron microscopy, it was shown that after y´ precipitates dissolution, the matrix close to the y/y interface is strongly enriched in Co and Cr and depleted in Al.

    Fulltekst (pdf)
    Springer
  • 9.
    Rehan, Arbab
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Medvedeva, Anna
    Uddeholms AB, S-68385 Hagfors, Sweden.
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Karlsson, Leif
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Retained Austenite Transformation during Heat Treatment of a 5 Wt Pct Cr Cold Work Tool Steel2017Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, nr 11, s. 5233-5243Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Retained austenite transformation was studied for a 5 wt pct Cr cold work tool steel tempered at 798 K and 873 K (525 degrees C and 600 degrees C) followed by cooling to room temperature. Tempering cycles with variations in holding times were conducted to observe the mechanisms involved. Phase transformations were studied with dilatometry, and the resulting microstructures were characterized with X-ray diffraction and scanning electron microscopy. Tempering treatments at 798 K (525 degrees C) resulted in retained austenite transformation to martensite on cooling. The martensite start (M-s) and martensite finish (M-f) temperatures increased with longer holding times at tempering temperature. At the same time, the lattice parameter of retained austenite decreased. Calculations from the Ms temperatures and lattice parameters suggested that there was a decrease in carbon content of retained austenite as a result of precipitation of carbides prior to transformation. This was in agreement with the resulting microstructure and the contraction of the specimen during tempering, as observed by dilatometry. Tempering at 873 K (600 degrees C) resulted in precipitation of carbides in retained austenite followed by transformation to ferrite and carbides. This was further supported by the initial contraction and later expansion of the dilatometry specimen, the resulting microstructure, and the absence of any phase transformation on cooling from the tempering treatment. It was concluded that there are two mechanisms of retained austenite transformation occurring depending on tempering temperature and time. This was found useful in understanding the standard tempering treatment, and suggestions regarding alternative tempering treatments are discussed. (C) The Author(s) 2017.

    Fulltekst (pdf)
    fulltext
  • 10.
    Segerstark, Andreas
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Svensson, Lars-Erik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Ojo, Olanrewaju
    University of Manitoba, Department of Mechanical Engineering,Winnipeg, R3T 5V6, Canada.
    Effect of Process Parameters on the Crack Formation in Laser Metal Powder Deposition of Alloy 7182018Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, nr 10, s. 5042-5050Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cracking in Alloy 718 using laser metal powder deposition has been evaluated in this study. It is found that the material is susceptible to cracking when the laser power is high, the scanning speed is high and the powder feeding rate is low. Almost all the cracks are located close to the center of the deposited wall and propagates in the normal direction to the substrate. Evidence of liquation are found at the cracked surfaces and since all cracks reside in regions which are reheated several times, the cracks are determined to mostlikely be heat affected zone liquation cracks. The influence of respective process parameter was evaluated using a design of experiment approach. It is shown that, when the powder feeding rate is incorporated as avariable, the heat input is not a suitable indicator for the hot cracking susceptibility in laser metal powder deposition of Alloy 718. A combinatory model using the power ratio together with the heat input is therefore proposed.

    Fulltekst (pdf)
    fulltext
  • 11.
    Singh, Sukhdeep
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, 412 96, Sweden.
    Hanning, Fabian
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Influence of Hot Isostatic Pressing on the Hot Ductility of Cast Alloy 718: The Effect of Niobium and Minor Elements on the Liquation Mechanism2020Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 51, nr 12, s. 6248-6257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of two hot isostatic pressing (HIP) treatments on liquation behavior was investigated and compared with regard to the extent of heat-affected zone liquation cracking in cast Alloy 718. The extent of liquation was seen to increase after HIP treatment at 1190 °C due to solute changes caused by the homogenization of Nb, which contributed to extensive grain boundary melting. The HIP treatment at 1120 °C exhibited lower liquation with contributions from particle liquation of the Laves phase and constitutional liquation of NbC carbides. This was also reflected in a lower ductility recovery temperature, with slower recovery for the former due to the extensive liquation. Interestingly, the nil ductility temperatures were both below the predicted equilibrium solidus of the alloy, which suggests that the ductility drop is related to liquation caused by solute segregation at the grain boundaries. © 2020, The Author(s).

  • 12.
    Tolvanen, Sakari
    et al.
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Pederson, Robert
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV). Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Klement, Uta
    Chalmers University of Technology, Department of Industrial and Materials Science, Gothenburg, Sweden.
    Microstructure and Porosity of Laser Welds in Cast Ti-6Al-4V with Addition of Boron2018Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 49A, nr 5, s. 1683-1691Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Addition of small amounts of boron to cast Ti-6Al-4V alloy has shown to render a finer microstructure and improved mechanical properties. For such an improved alloy to be widely applicable for large aerospace structural components, successful welding of such castings is essential. In the present work, the microstructure and porosity of laser welds in a standard grade cast Ti-6Al-4V alloy as well as two modified alloy versions with different boron concentrations have been investigated. Prior-β grain reconstruction revealed the prior-β grain structure in the weld zones. In fusion zones of the welds, boron was found to refine the grain size significantly and rendered narrow elongated grains. TiB particles in the prior-β grain boundaries in the cast base material restricted grain growth in the heat-affected zone. The TiB particles that existed in the as cast alloys decreased in size in the fusion zones of welds. The hardness in the weld zones was higher than in the base material and boron did not have a significant effect on hardness of the weld zones. The fusion zones were smaller in the boron-modified alloys as compared with Ti-6Al-4V without boron. Computed tomography X-ray investigations of the laser welds showed that pores in the FZ of the boron modified alloys were confined to the lower part of the welds, suggesting that boron addition influences melt pool flow. © 2018 The Author(s)

  • 13.
    Venkatesh, Lakshmi Narayanan
    et al.
    Int Adv Res Ctr Powder Met & New Mat ARCI, Hyderabad 500005, Andhra Pradesh, India.
    Babu, Pitchuka Suresh
    Int Adv Res Ctr Powder Met & New Mat ARCI, Hyderabad 500005, Andhra Pradesh, India.
    Gundakaram, Ravi Chandra
    Int Adv Res Ctr Powder Met & New Mat ARCI, Hyderabad 500005, Andhra Pradesh, India.
    Doherty, Roger D.
    Drexel Univ, Dept Mat Engn, Philadelphia, PA 19104 USA.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Samajdar, Indradev
    Indian Inst Technol, Dept Met Engn & Mat Sci, Mumbai 400076, Maharashtra, India.
    Morphology-Dependent Hardness of Cr7C3-Ni-Rich Alloy Composite vs Orientation Independent Hardness of Cr7C3 Primary Phase in a Laser Clad Microstructure2017Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 48A, nr 4, s. 1534-1539Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microstructural evolution with superheating was studied in chromium carbide-nickel coatings deposited by laser cladding. At lower superheating, selective growth of aOE (c) 0001 > direction from the high density of Cr7C3 grains nucleated resulted in a columnar structure with (0001) texture. Increased superheating lead to the loss of columnar structure as well as the (0001) texture. The hexagonal Cr7C3 showed an unusual isotropic nanoindentation hardness evidently correlated with its low c/a ratio. However, the rod-like morphology of the carbide dendrites resulted in significant anisotropy in the hardness of the composite.

1 - 13 of 13
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf