Change search
Refine search result
1 - 11 of 11
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Chen, Kaixuan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Chen, Xiaohua
    Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing 100083, Peoples R China..
    Wang, Zidong
    Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China..
    Mao, Huahai
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Optimization of deformation properties in as-cast copper by microstructural engineering. Part I. microstructure2018In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 763, p. 592-605Article in journal (Refereed)
    Abstract [en]

    The microstructural features required to optimize both the strength and ductility of copper are investigated by examining the as-cast pure Cu and Cu-(1.0e3.0)Fe-0.5Co and Cu-1.5Fe-0.1Sn (wt %) alloys. Uniaxial tensile tests show that (Fe, Co)- or (Fe, Sn)-doping improves both the strength and ductility of pure copper. The microstructure evolution with Fe, Co, or Sn doping is characterized by using optical and scanning and transmission electron microscopies. The effects of Fe, Co, and Sn doping on the microstructure clearly show that (i) iron-rich nanoparticles are dispersed inside the grains. The spherical nanoparticles grow in size with increasing Fe content, and when the Fe content exceeds 2.0 wt %, the particles transition into a petal-like morphology. (ii) The microstructure of the alloys (grain size and morphology) is notably influenced by the Fe and Co contents, and the grain size is reduced from an average of 603 mu m in pure Cu to an average of 26 mm in the Cu-3.0Fe-0.5Co alloy. (iii) The addition of 1.5wt % Fe and 0.1wt % Sn dramatically reduces the grain size to an average of 42 mu m, and this reduction is correlated with the appearance of smaller spherical iron-rich nanoparticles. The evolution mechanisms of the iron-rich nanoparticles and grain structure under the alloying effect are discussed.

  • 2.
    Delandar, Arash Hosseinzadeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. KTH Royal Inst Technol, Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE. KTH Royal Inst Technol, Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    Korzhavyi, Pavel A.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics. KTH Royal Inst Technol, Mat Sci & Engn, SE-10044 Stockholm, Sweden..
    The Role of Glide during Creep of Copper at Low Temperatures2018In: METALS, ISSN 2075-4701, Vol. 8, no 10, article id 772Article in journal (Refereed)
    Abstract [en]

    Copper canister will be used in Scandinavia for final storage of spent nuclear fuel. The copper will be exposed to temperatures of up to 100 degrees C. The creep mechanism at near ambient temperatures has been assumed to be glide of dislocations, but this has never been verified for copper or other materials. In particular, no feasible mechanism for glide based static recovery has been proposed. To attack this classical problem, a glide mobility based on the assumption that it is controlled by the climb of the jogs on the dislocations is derived and shown that it is in agreement with observations. With dislocation dynamics (DD) simulations taking glide but not climb into account, it is demonstrated that creep based on glide alone can reach a quasi-stationary condition. This verifies that static recovery can occur just by glide. The DD simulations also show that the internal stress during creep in the loading direction is almost identical to the applied stress also directly after a load drop, which resolves further classical issues.

  • 3.
    He, Junjing
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Notargiacomo, Sandro
    Low-Cycle Fatigue Properties of a Nickel-Based Superalloy Haynes 282 for Heavy Components2017In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 26, no 5, p. 2257-2263Article in journal (Refereed)
    Abstract [en]

    Low-cycle fatigue (LCF) tests of the nickel-based superalloy Haynes 282 from a large forged ingot were conducted at 25 and 750 degrees C with total strain ranges from 0.7 to 1.7%. Compared with other tests on this alloy, it was found that the LCF properties showed similar results at room temperature, but improved number of cycles to failure at high temperatures. The number of cycles at a given total strain range showed no large differences between the core and rim positions. By comparing with two other types of low gamma' volume fraction nickel-based superalloys, Haynes 282 gave the best LCF properties at high temperatures. The reason may be due to the dominating transgranular fracture in the current work. A mixture of intergranular and transgranular fractures had been observed in the other alloys. The results demonstrate that heavy components of Haynes 282 can be produced with good LCF properties.

  • 4.
    Magnusson, Hans
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Creep modelling of particle strengthened steels2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Materials used in thermal power plants have to resist creep deformation for time periods up to 30 years. Material evaluation is typically based on creep testing with a maximum duration of a few years. This information is used as input when empirically deriving models for creep. These kinds of models are of limited use when considering service conditions or compositions different from those in the experiments. In order to provide a more general model for creep, the mechanisms that give creep strength have to be identified and fundamentally described. By combining tools for thermodynamic modelling and modern dislocation theory the microstructure evolution during creep can be predicted and used as input in creep rate modelling. The model for creep has been utilised to clarify the influence of aluminium on creep strength as a part of the European COST538 action. The results show how AlN is formed at the expense of MX carbonitrides. The role of heat treatment during welding has been analysed. It has been shown that particles start to dissolve already at 800ºC, which is believed to be the main cause of Type IV cracking in commercial alloys.

    The creep strength of these steels relies on minor additions of alloying elements. Precipitates such as M23C6 carbides and MX carbonitrides give rise to the main strengthening, and remaining elements produce solid solution hardening. Particle growth, coarsening and dissolution have been evaluated. By considering dislocation climb it is possible to determine particle strengthening at high temperatures and long-term service. Transient creep is predicted by considering different types of dislocations. Through the generation and recovery of dislocation densities an increase in work hardening during primary creep is achieved. The role of substructure is included through the composite model. Cavity nucleation and growth are analysed in order to explain the intergranular fracture and to estimate the ductility.

  • 5.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Creep strain modelling of 9-12 Pct Cr steels based on microstructure evolution2007In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 38, no 9, p. 2033-Article in journal (Refereed)
    Abstract [en]

    Creep deformation is simulated for 9 pct Cr steels by using the Norton equation with the addition of back stresses from dislocations and precipitates. The composite model is used to represent the heterogeneous dislocation structure found in 9 to 12 pct Cr steels. Dislocation evolution is modeled by taking capturing and annihilation of free dislocations into account. Recovery of immobile dislocations is derived from the ability of dislocation climb. In spite of the fact that the initial dislocation density is high and is reduced during creep, primary creep is successfully modeled for a P92 steel. Subgrain growth is evaluated using a model by Sandström (1977). The long time subgrain size corresponds well to a frequently used empirical relation, with subgrain size inversely proportional to the applied stress.

  • 6.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Growth of Creep Cavities in 12% Cr Steels2009In: Creep & Fracture in High Temperature Components – Design & Life Assessment, 2nd International ECCC Conference, Empa, Dübendorf, Switzerland, 21-23 April, 2009 / [ed] I A Shibli, S R Holdsworth, LANCASTER, PA: DESTECH PUBLICATIONS, INC , 2009, p. 950-963Conference paper (Refereed)
    Abstract [en]

    The nucleation and growth of creep cavities will eventually occupy a considerable fraction ofthe grain boundary. This will lead to microcracks and intergranular fracture thus controllingthe ductility of the component. The traditional approach to predicting this type of failure is tosimulate cavities with only one size. Assumptions of an instant nucleation with symmetricallyplaced cavities make all cavities equally sized. It has been observed, in 12% Cr steels as wellas in other commercial alloys that cavities nucleate during all stages of creep. Creep cavitiesget randomly placed mostly at grain boundaries directed transverse to the loading direction.With continuous nucleation a size distribution of cavities appears, which is compared toobserved average cavity size. Constraints on cavity growth are introduced, which reduces thegrowth rate. This is needed in order to explain the cavity growth of 12% Cr steels.Furthermore, creep rupture will be derived based on the area fraction of cavities, thus explaining the intergranular failure.

  • 7.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Influence of aluminium on creep strength of 9–12% Cr steels2009In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 527, p. 118-125Article in journal (Refereed)
    Abstract [en]

    The influence of aluminium on creep strength of 9% Cr steels is predicted by a fundamental model forcreep. Through thermodynamic modelling the particle structure is determined for a temperature andcomposition range. This shows how AlN is formed at the expense of MX carbonitrides of VN characterwhen the aluminium content is increased. The remaining MX particles are of NbC type and have approximatelyone fifth of the original phase fraction. The evolution in microstructure such as particle coarseningis included in the model as well as the recovery. Rupture time is predicted using a modified Norton equationincluding back-stresses calculated from microstructure. The predictions show correspondence tosome of the creep data for the steel P91 over a temperature and stress range. Furthermore, simulationwith high Al content verifies the observed early failure of Al rich components. Overall, the simulationsshow a decrease in rupture time by a factor 6 due to Al additions of up to 0.2%.

  • 8.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Modeling Creep Strength of Welded 9 to 12 Pct Cr Steels2010In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 41A, no 13, p. 3340-3347Article in journal (Refereed)
    Abstract [en]

    The influence of weld simulated heat treatments of 9-12% steels is evaluated by a fundamental model for creep. The heat affected microstructure is predicted by considering particle coarsening, particle dissolution, and subgrain coarsening. Particle coarsening is predicted for a multi-component system, showing significant M23C6 coarsening in the BCC matrix. Dissolution simulations of MX and M23C6 are performed by considering a size distribution of particles, indicating that the smallest particles can be dissolved already at relatively low welding temperatures. Recovery in dislocation networks will take place due to the coarser particles. Creep rate modelling is performed based on the heat affected microstructure, showing strength reduction of weld simulated material by 12% at 850ºC and 26% at 900ºC. The main cause of this degradation is believed to be the loss of the smallest carbonitrides.

  • 9.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Modelling of the influence of Laves phase on the creep properties in 9% Cr steels2007In: PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE / [ed] Jaske, CE; Jaske, CE, 2007, p. 519-526Conference paper (Refereed)
    Abstract [en]

    Nucleation and growth of Laves phase are calculated for a multi-component system. Coarsening Of MX, M23C6 and Laves are also determined. The influence on creep strength is discussed by analysing particle hardening and solid solution strengthening. A model for particle size distribution is presented in order to determine the amount of dislocations that can climb across particles or generate Orowan loops.

    The model for solid solution hardening is based on a solution of Fick's second law with a moving frame of reference for the concentration profiles around a climbing dislocation. This is done in order to determine the slowdown in dislocations velocity due to solute drag. The results show a loss in creep strength as the Laves phase grows.

  • 10.
    Magnusson, Hans
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    The role of dislocation climb across particles at creep conditions in 9 to 12 pct Cr steels2007In: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 38A, no 10, p. 2428-2434Article in journal (Refereed)
    Abstract [en]

    The influence of a distribution of particles on creep strength is analyzed. The time it takes for dislocations to climb across the particles is the basis for a model that can describe the effect of particle size distribution, particle area fraction, stress, and temperature on the creep rate. The degradation of microstructure through coarsening is taken into account. The particle size distributions for M23C6 carbides and MX carbonitrides in a 9 pct Cr steel are accurately represented by an exponential function. Coarsening coefficients and phase fractions for MX and M23C6 particles are predicted using thermodynamic modeling, and show good fit to experimental data. The size distributions are used to determine the amount of dislocations, which can either climb across particles or make Orowan loops. The dislocation climb model is integrated into a creep rate prediction model and is used to reproduce experimental creep data for P92 steel.

  • 11.
    Sui, Fangfei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Sandström, Rolf
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology. KTH, School of Industrial Engineering and Management (ITM), Centres, Brinell Centre - Inorganic Interfacial Engineering, BRIIE.
    Wu, Rui
    Swerea KIMAB, Drottning Kristinas Vag 38, S-11428 Stockholm, Sweden..
    Creep tests on notched specimens of copper2018In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 509, p. 62-72Article in journal (Refereed)
    Abstract [en]

    In Sweden, spent nuclear fuel is planned to be disposed off by placing it in canisters which are made of oxygen free copper alloyed with 50 ppm phosphorus. The canisters are expected to stay intact for thousands of years. During the long term disposal, the canisters will be exposed to mechanical pressure from the surroundings at temperatures up to 100 degrees C and this will result in creep. To investigate the role of the complex stress conditions on the canisters, creep tests under multiaxial stress state are needed. In the present work, creep tests under multiaxial stress state with three different notch profiles (acuity 0.5, 2, and 5, respectively) at 75 degrees C with net section stresses ranging from 170 MPa to 245 MPa have been performed. To interpret the experimental results, finite element computations have been conducted. With the help of the reference stress, the rupture lifetime in the multiaxial tests was estimated. The prediction was more precise for the higher acuities than for the lower one. In order to predict the creep deformation of the canisters for the long service period, fundamental creep models are considered. Previously developed basic models are used to compute the creep deformation in the multiaxial tests. Although the scatter is large, the agreement with the experiments is considered as acceptable, indicating that the basic models which have been successfully developed for uniaxial creep tests can also be used to describe multiaxial creep tests. Notch strengthening was observed for copper.

1 - 11 of 11
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf