Endre søk
Begrens søket
1 - 15 of 15
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.
    Babu, Prasath
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Indian Institute of Science, Bangalore, India.
    Vamsi, K. V.
    Karthikeyan, S.
    On the formation and stability of precipitate phases in a near lamellar γ-TiAl based alloy during creep2018Inngår i: Intermetallics (Barking), ISSN 0966-9795, E-ISSN 1879-0216, Vol. 98, s. 115-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The formation, evolution and stability of metastable phases observed in the γ-TiAl based alloy Ti-47Al-2Cr-2Nb was studied under creep deformation with stress applied at two different hard orientations in a highly textured as-cast + HIPed material. Previously we have reported that the metastable phase Ti(Al,Cr)2 with C14 Laves phase structure forms at the γ-α2 interface which acts as sink for the alloying elements ejected from the dissolving α2 phase and also expected to effectively control the interface stresses through short range diffusion and modifications in the chemical composition [1]. Ab initio density functional theory based calculations were carried out to evaluate the effect of choice of lattice position and site occupancy of aluminium atoms in the Ti(Al,Cr)2 structure on the lattice parameter variation and thermodynamic stability. C14 with the composition 25 at. % Al was found to have lattice parameter values close to the inter-planar spacing of <110>γ and <10-10>α2 which would have a lower misfit with C14 across the interface. From the cohesive energy calculations, Laves phase C14 with a constrained lattice parameter due to the adjoining phases, exhibits higher stability than the B2 and L10 structures across a range of compositions studied. Electron diffraction simulations of C14 with a composition of 25% Al compared with the experimental data suggest that the structure C14 has taken up either a random site occupancy compared to a specific choice of ordering to minimize the interfacial stress. Though the experimental evidences do not strongly support a long-range ordering theory in C14, short-range ordering could be a tangible choice for alleviating interface misfits. The ability of C14 to assume different lattice parameters at and far from the α2-γ interface also suggest that the C14 acts as buffer layer between α2 and γ phases in the presence of local stresses, although this is not the thermodynamically expected phase at the temperature of creep experiment.

  • 2.
    Francis, E.
    et al.
    Univ Manchester, Sch Mat, MSS Tower, Manchester M1 3BB, Lancs, England..
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Harte, A.
    Univ Manchester, Sch Mat, MSS Tower, Manchester M1 3BB, Lancs, England..
    Martin, T. L.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.;Univ Bristol, Tyndall Ave, Bristol, Avon, England..
    Frankel, R.
    Univ Manchester, Sch Mat, MSS Tower, Manchester M1 3BB, Lancs, England..
    Jadernas, D.
    Studsvik Nucl AB, Nykoping, Sweden.;Idaho Natl Lab, POB 1625, Idaho Falls, ID USA..
    Romero, J.
    Westinghouse Elect Sweden AB, Vasteras, Sweden..
    Halistadius, L.
    Westinghouse Elect Co, Columbia, SC USA..
    Bagot, P. A. J.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England..
    Moody, M. P.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England..
    Preuss, M.
    Univ Manchester, Sch Mat, MSS Tower, Manchester M1 3BB, Lancs, England..
    Effect of Nb and Fe on damage evolution in a Zr-alloy during proton and neutron irradiation2019Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 165, s. 603-614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Detailed analysis was carried out on proton and a neutron irradiated Nb-containing Zr-alloy to study the evolution of dislocation loop size and densities as well as the formation and evolution of irradiation induced precipitation/clustering. The results obtained here have been contrasted against previously published work on a Nb-free Zr-alloy [1, 21 to investigate the mechanistic reason for the improved resistance to irradiation-induced growth of Nb-containing Zr alloys. The combined use of bright field scanning transmission electron microscopy, ultra-high-resolution energy dispersive spectroscopy and atom probe tomography analysis provides evidence of evenly distributed radiation-induced Nb dusters that have formed during the early stage of proton irradiation and Fe-rich nano-rods near Fe-containing second phase particles. The former seems to have a profound effect on <a> loop and subsequent <c> loop formation, keeping <a> loop size small but number density high while <c> loops seem to initially form at similar dose levels compared to a Nb-free alloy but <c> loop line density does not increase during further irradiation. It is hypothesized that the formation of the Nb nano-precipitates/clusters significantly hinders mobility and growth of <a> loops, resulting in a small size, high number density and limited ability of <a> loops to arrange along basal traces compared to Nb-free Zr-alloys. It is suggested that it is the limited <a> loop arrangement that slows down <c> loop formation and the root cause for the high resistance of Nb-containing Zr-alloys to irradiation-induced growth. 

  • 3.
    Hoseini-Athar, M. M.
    et al.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Mahmudi, R.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Effect of Zn addition on dynamic recrystallization behavior of Mg-2Gd alloy during high-temperature deformation2019Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 806, s. 1200-1206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of Zn/Gd ratio on dynamic recrystallization (DRX) of Mg-2Gd-xZn (x = 0, 1, 2 and 3 wt%) alloys was investigated by shear punch tests in the temperature range of 623-723 K and shear strain rate range of 1.0 x 10(-2)-1.2 x 10(-1) s(-1). It was observed that at low Zn/Gd ratio, excessive co-segregation of Gd and Zn solute atoms retards recrystallization and provides higher strength. At high Zn/Gd ratios, precipitation reduces the co-segregation, so that the alloy with Zn/Gd = 1.5, experienced the fastest DRX and the lowest strength. In addition, segregation resulted in a weaker texture, by elimination of nucleation and growth of the preferred orientations. rights reserved.

  • 4.
    Hoseini-Athar, M. M.
    et al.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Mahmudi, R.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Microstructural evolution and superplastic behavior of a fine-grained Mg-Gd alloy processed by constrained groove pressing2019Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 754, s. 390-399Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the current study, microstructural evolution and superplasticity of an extruded Mg-2wt% Gd sheet were studied after the constrained groove pressing (CGP) process. Microstructural observations by scanning electron microscopy and electron backscattered diffraction revealed that after 4 cycles of CGP, a rather homogeneous fine-grained microstructure with an average grain size of 4.3 mu m, and a large fraction of high angle grain boundaries was obtained. By performing shear punch tests (SPT) at different temperatures and various shear strain rates, a peak strain rate sensitivity index (m-value) of 0.49 was obtained after 4 cycles of CGP process at 673 K, while peak m-values of 0.31 and 0.36 were obtained for the as-extruded and 2 cycle CGP process conditions, respectively. An m-value of 0.49 and an activation energy of 113 kJ/mol, obtained for the fine-grained material after 4 cycles of CGP, suggest that the dominant deformation mechanism in the superplastic regime is grain boundary sliding (GBS) controlled by grain boundary diffusion.

  • 5.
    Hoseini-Athar, M. M.
    et al.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Mahmudi, R.
    Univ Tehran, Coll Engn, Sch Met & Mat Engn, Tehran, Iran..
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Microstructure, texture, and strain-hardening behavior of extruded Mg-Gd-Zn alloys2020Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 772, artikkel-id 138833Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of Zn content on the microstructure, texture, mechanical properties and strain-hardening behavior of extruded Mg-2Gd-xZn (x = 0, 1, 2 and 3 wt%) sheets was investigated. Evaluation of texture revealed that while all of the alloys exhibited weak textures, the texture component was altered from a basal to a non-basal one by the addition of Zn. A typical transverse direction (TD) split texture with basal poles rotated about 40 degrees from the normal direction (ND) toward TD was observed for the Zn-containing alloys, the effect being more pronounced at higher Zn contents. Furthermore, the Mg-2Gd-1Zn alloy exhibited the weakest texture due to solute drag imposed by co-segregation of Zn and Gd atoms at grain boundaries. Addition of Zn also resulted in a general increase in yield stress, ultimate tensile strength and elongation along the extrusion direction from 99 to 172 MPa, 178 to 263 MPa, and 25 to 35% for Mg-2Gd and Mg-2Gd-3Zn alloys, respectively. However, increasing Zn content was accompanied by an initial decrease in anisotropy of mechanical properties and strain-hardening behavior, followed by an increase at higher Zn contents. This was due to the difference of orientation of basal planes with regard to tension direction. As a result, lower yield stress, higher elongation and strain-hardening capacity was obtained along TD (with higher Schmid factor for basal slip) compared to ED. It was concluded that excellent mechanical properties and low anisotropy can be achieved in the Mg-2Gd-1Zn alloy.

  • 6.
    Hou, Ziyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Coarsening of cementite during tempering of a martensitic steelManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Coarsening of cementite (M3C) in a martensitic steel alloy Fe–1C–1Cr (wt. %) during tempering at 700 °C was investigated by electron microscopy and kinetic modelling. It is shown that the large M3C carbides are mostly located at high-angle grain boundaries in the coarsening stage and simple kinetic simulations predict the experimentally observed mean size evolution well when grain boundary diffusion of Cr is taken into account. However, the particle size distribution of M3C maintain a log-normal distribution throughout the whole extended tempering process (5000 h at 700 °C), which indicates that a modified LSW distribution , as predicted by classical steady-state coarsening theory , is not fully adequate for practical purposes in tempering of martensitic steels.

  • 7.
    Hou, Ziyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Early stages of cementite precipitation during tempering of 1C-1Cr martensitic steelManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The precipitation of cementite (M3C) from as-quenched martensite during tempering at 500 and 700 °C was investigated in a Fe–1C–1Cr (wt. %) alloy. Tempering for a short duration at 700 °C results in a Cr/Fe ratio in the core region of M3C precipitates which is equal to the bulk alloy composition, while a shell on the surface of the precipitates exhibit a higher Cr concentration. With a prolonged tempering up to 5 hours, the shell concentration gradually increases towards the equilibrium value but the core region has not yet reached the equilibrium value. After tempering for 5 seconds at 500 °C, there is no Cr enrichment found at the M3C/matrix interface, while a transition to partitioning of Cr is found during the first 5 minutes of tempering at 500 °C. These experimental results indicate that M3C grows without significant partitioning of substitutional elements at both temperatures initially, i.e. growth is carbon diffusion controlled. This stage is, however, very short, and soon after 5 seconds at 700 °C and 5 min at 500 °C, Cr diffusion becomes important. Calculations using the diffusion simulation software DICTRA and precipitation simulation software TC-PRISMA were performed. The diffusion simulations using the local equilibrium interface condition show excellent agreement with experiments concerning Cr enrichment of the particles, but the size evolution is overestimated. On the other hand, the precipitation simulations underestimate the size evolution. It is suggested that a major improvement in the precipitation model could be achieved by implementing a modified nucleation model that considers nucleation far from the equilibrium composition.

  • 8.
    Hou, Ziyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Xu, Yunbo
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Wu, Di
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Enhanced Grain Growth Behavior of Ferritic Steel during Continuous Cyclic Annealing2018Inngår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, nr 11, artikkel-id 1800222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microstructural characterization as well as mechanical property determination of a cold-rolled ferritic steel subjected to isothermal and cyclic non-isothermal annealing, has been carried out by utilizing comprehensive experimental analysis. The findings show that the variables of cyclic annealing, that is, amplitude, ramp rate, and intermediate holding time exhibit a great effect on the grain growth kinetics and the evolution of grain boundaries. The resulting grain size of the cyclic annealed steel is mainly attributed to the following factors: 1) the accelerating effect in the grain growth behavior caused by the additional driving force available during cyclic annealing, which increases with increasing amplitude; 2) the retarding effect due to the low equivalent isothermal temperature. Furthermore, the formation of low sigma- coincidence site lattice (sigma CSL) boundaries and the strength of gamma-fiber texture are enhanced through the cyclic annealing compared to the isothermal annealing. The potential advantages of continuous cyclic annealing in the steel industry are explored, in comparison with the conventional isothermal and cyclic annealing with an intermediate soaking time.

  • 9.
    Hou, Ziyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Babu, R. Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Early stages of cementite precipitation during tempering of 1C-1Cr martensitic steel2019Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, nr 12, s. 9222-9234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The precipitation of cementite (M3C) from as-quenched martensite during tempering at 500 and 700 degrees C was investigated in a Fe-1C-1Cr (wt%) alloy. Tempering for a short duration at 700 degrees C results in a Cr/Fe ratio in the core region of M3C precipitates which is equal to the bulk alloy composition, while a shell on the surface of the precipitates exhibits a higher Cr concentration. With a prolonged tempering up to 5h, the shell concentration gradually increases toward the equilibrium value, but the core region has not yet reached the equilibrium value. After tempering for 5s at 500 degrees C, there is no Cr enrichment found at the M3C-matrix interface, while a transition to partitioning of Cr is found during the first 5min of tempering at 500 degrees C. These experimental results indicate that M3C grows without significant partitioning of substitutional elements at both temperatures initially, i.e., growth is carbon diffusion controlled. This stage is, however, very short, and soon after 5s at 700 degrees C and 5min at 500 degrees C, Cr diffusion becomes important. Calculations using the diffusion simulation software DICTRA and precipitation simulation software TC-PRISMA were performed. The diffusion simulations using the local equilibrium interface condition show excellent agreement with experiments concerning Cr enrichment of the particles, but the size evolution is overestimated. On the other hand, the precipitation simulations underestimate the size evolution. It is suggested that a major improvement in the precipitation model could be achieved by implementing a modified nucleation model that considers nucleation far from the equilibrium composition.

  • 10.
    Hou, Ziyong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Northeastern Univ, State Key Lab Rolling & Automat, Shenyang 110819, Liaoning, Peoples R China.
    Babu, R. Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Microstructure evolution during tempering of martensitic Fe-C-Cr alloys at 700 A degrees C2018Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 53, nr 9, s. 6939-6950Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The microstructure evolution of two martensitic alloys Fe-0.15C-(1.0 and 4.0) Cr (wt%) was investigated, using X-ray diffraction, electron backscatter diffraction, electron channeling contrast imaging and transmission electron microscopy, after interrupted tempering at 700 A degrees C. It was found that quenching of 1-mm-thick samples in brine was sufficient to keep most of the carbon in solid solution in the martensite constituent. The high dislocation density of the martensite decreased rapidly during the initial tempering but continued tempering beyond a few minutes did not further reduce the dislocation density significantly. The initial martensitic microstructure with both coarse and fine laths coarsened slowly during tempering for both alloys. However, a clear difference between the two alloys was distinguished by studying units separated by high-angle boundaries (HABs). In the low-Cr alloy, M3C precipitates formed and coarsened rapidly, thus they caused little hindrance for migration of HABs, i.e., coarsening of the HAB units. On the other hand, in the high-Cr alloy, M7C3 precipitates formed and coarsened slowly, thus they were more effective in pinning the HABs than M3C in the low-Cr alloy, i.e., coarsening of HAB units was minute in the high-Cr alloy.

  • 11.
    Wang, Wei
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Dept Chemical Engineering, Northeast Electric Power University, Jilin, 132012, China.
    Hou, Ziyong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Lizarrága, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Tian, Ye
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Holmström, Erik
    Coromant R & D, SE-12680, Stockholm, Sweden.
    Mao, Huahai
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Thermo-Calc Software, Råsundav. 18, SE-16767, Solna, Sweden.
    Larsson, Henrik
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi. Thermo-Calc Software, Råsundav. 18, SE-16767, Solna, Sweden.
    An experimental and theoretical study of duplex fcc+hcp cobalt based entropic alloys2019Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 176, s. 11-18Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Martensitically formed duplex fcc + hcp Co-based entropic alloys have been investigated both experimentally and theoretically. Theoretical predictions are in good agreement with experimental observations. A fair correlation is found between calculated driving forces for a partitionless fcc→hcp transformation and experimentally obtained phase fractions.

  • 12.
    Zhou, Tao
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hou, Ziyong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Odqvist, Joakim
    KTH, Tidigare Institutioner (före 2005), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Precipitation of multiple carbides in martensitic CrMoV steels -experimental analysis and exploration of alloying strategy through thermodynamic calculationsManuskript (preprint) (Annet vitenskapelig)
    Fulltekst tilgjengelig fra 2020-12-31 17:36
  • 13.
    Zhou, Tao
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. University of Science and Technology Beijing, China.
    Babu, R. Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Yu, Hao
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Quantitative electron microscopy and physically based modelling of Cu precipitation in precipitation-hardening martensitic stainless steel 15-5 PH2018Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 143, s. 141-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Precipitation-hardening martensitic stainless steels rely on very fine precipitates for optimal mechanical performance. These multicomponent alloys are prone to clustering and precipitation reactions during tempering, where Cu is one of the alloying elements added to stimulate precipitation. It is efficient to use an integrated computational materials engineering (ICME) approach to tailor alloying and heat treatment for design of these alloys. The most promising physically based modelling of precipitation for this purpose at present is Langer-Schwartz-Kampmann-Wagner (LSKW) modelling within the CALPHAD framework. This approach has been successful for model alloys, but reliable results for mulhcomponent stainless steels are less common. Hence, we combine quantitative transmission electron microscopy and LSKW modelling to investigate the tempering of a martensitic stainless steel 15-5 PH at 500 degrees C. The microstructural characterization shows that the Cu precipitation and growth occur in three stages: i) Cu BCC, n) Cu 9R, and iii) Cu FCC, during tempering up to 1000 h. The modelling predictions of size, volume fraction and number density of precipitates are in good agreement with the experimental results. Thus, the approach with a combination of quantitative electron microscopy and LSKW modelling using CALPHAD-type databases holds promise for further optimization of precipitation-hardening martensitic stainless steels.

  • 14.
    Zhou, Tao
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Faleskog, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Odqvist, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Yu, Hao
    Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China..
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Exploring the relationship between the microstructure and strength of fresh and tempered martensite in a maraging stainless steel Fe-15Cr-5Ni2019Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 745, s. 420-428, artikkel-id DELL AJ, 1985, METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, V16, P2131Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hierarchical microstructure engineering is an efficient design path for ultra-high strength steels. An excellent example of this is maraging stainless steel, which achieves its high-performance by combining the hierarchic martensitic microstructure and nano-sized precipitates. Relating this complex microstructure with mechanical properties, e.g. strength, is not trivial. In the present work, we therefore explore the relationship between the hierarchic microstructure, evolving with the tempering of a Cu-containing maraging stainless steel 15-5 PH, and its strength. Comprehensive microstructure characterization, including the quantification of dislocation density, effective grain size, precipitates and retained austenite fraction is performed after quenching and tempering at 500 degrees C. The microstructure data is subsequently used as input for assessing the evolution of individual strength contributions and thus the increase in strength of tempered martensite contributed by Cu precipitation strengthening is evaluated. It is found that the Cu precipitation and dislocation annihilation are two major factors controlling the evolution of the yield strength of the tempered martensite. The Cu precipitation strengthening is also modelled using our previous Langer-Schwartz-Kampmann-Wagner model based predictions of the Cu precipitation, and modelled precipitation strengthening is compared with the evaluated Cu precipitation strengthening from the experiments. The work exemplifies the promising approach of combining physically based precipitation modelling and precipitation-strengthening modelling for alloy design and optimization. However, more work is needed to develop a generic predictive framework.

  • 15.
    Zhou, Tao
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hou, Ziyong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Babu, Prasath
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Recent developments in transmission electron microscopy based characterization of precipitation in metallic alloysManuskript (preprint) (Annet vitenskapelig)
1 - 15 of 15
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