du.sePublikationer
Ändra sökning
Avgränsa sökresultatet
1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Engberg, Göran
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Lissel, Linda
    A Physically based Microstructure Model for Predicting the Microstructure Evolution of a C-Mn Steel during and after Deformation2008Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 79, nr 1, s. 47-58Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A physically based model for predicting microstructural evolution has been developed. The model is based on a physical description of dislocation density evolution, where the generation and recovery of dislocations determine the flow stress and also the driving force for recrystallization. In the model, abnormally growing subgrains are assumed to be the nuclei of recrystallized grains and recrystallization starts when the subgrains reach a critical size and configuration. To verify that the model is able to describe dynamic, static and metadynamic recrystallization of C-Mn steels, hot compression tests combined with relaxation were performed at various temperatures, strains and strain rates. The model showed reasonable agreement with the experimental data for the compression tests performed at temperatures ranging from 850?C to 1200?C and strain rates ranging from 0.1 to 10 s-1. Also, the calculations of the stress relaxation tests show good agreement with experimental data. A validation of the model was done by calculating a multi-step test where good agreement with both flow-stress values and grain sizes was obtained. The main purpose of the model is to be able to predict the microstructural evolution during hot rolling and this investigation presents very promising results.

  • 2. Filipovic, Mirjana
    et al.
    Eriksson, Conny
    Överstam, Henrik
    Behaviour of Surface Defects in Wire Rod Rolling2006Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 77, nr 6, s. 439-444Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Defects are often present in rolled products, such as wire rod. The markets demand for wire rod without any defects has increased. In the final wire rod products, defects originating from the steel making, casting, pre-rolling of billets and during the wire rod rolling can appear. In this work, artificial V-shaped longitudinal surface cracks has been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to a fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V-shape or if it will be closed as an I-shape.

  • 3. Granbom, Ylva
    Effects of process parameters prior to annealing on the formability of two cold rolled dual phase steels2008Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 79, nr 4, s. 297-305Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study concerns the effects of coiling temperature after hot rolling and the degree of reduction during cold rolling on formability-related properties of high strength cold rolled dual phase (DP) steels. The effect of coiling temperature on the final structure and properties of two cold rolled and annealed DP-steels is investigated. Further, the effect of cold rolling reduction and its impact on the final properties of the material is studied. Aspects of the impact of the different process parameters on the ferrite to austenite and austenite to martensite transformation are discussed based on results from production scale experiments, tensile testing and metallographic examinations of the materials.

  • 4.
    Granbom, Ylva
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialvetenskap.
    Ryde, Lena
    Jeppsson, Johan
    Simulation of the soaking and gas jet cooling in a continuous annealing line using dilatometry2010Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 81, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study concerns the simulation of a continuous annealing line (CAL), using dilatometry. Simulations of CAL have been performed on four commercial steel grades with different chemical compositions in order to investigate how the alloying elements C, Mn, Si and B affect the microstructure and hardness of dual phase (DP) and martensitic steels. Three annealing cycles corresponding to those used in a CAL have been applied. When annealing intercritically, as is the case in DP-steel production, the materials do not reach equilibrium during soaking. Mn and C increase the austenite content and consequently the hardness of the materials. Higher levels of Si (0.4?wt %) are required to retard the formation of new ferrite during cooling in the gas jet section, prior to quenching. B increases hardenability effectively when annealing in the austenite region but is not as efficient during intercritical annealing, which implies that boron restrains ferrite nucleation rather than impeding ferrite growth. Results from DICTRA calculations show that it is possible to simulate the phase transformations during soaking, gasjet cooling and quenching.

  • 5. Karasev, A. V.
    et al.
    Kellner, Hans
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Sundqvist, O.
    Memarpour, A.
    Jönsson, P. G.
    Estimation of non-metallic inclusions in industrial Ni based alloys 8252017Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, nr 4, artikel-id 1600024Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is well known that inclusions affect the properties of the steel and other alloys. The importance of understanding the behavior of the inclusions during production can never be overstated. This study has examined the main types of big size (>10μm) inclusions that exist in Ni-based Alloy at the end of ladle treatment and after casting during industrial production of Ni based Alloys 825. Sources, mechanisms of formation and behavior of different type large size inclusions in Alloy 825 are discussed based on 2 and 3D investigations of inclusion characteristics (such as, morphology, composition, size, and number) and thermodynamic considerations. The large size inclusions found can be divided in spherical (Type I and II) inclusions and in clusters (Type III-V). Type I-A inclusions (Al2O3-CaO-MgO) originate from the slag. Type I-B inclusions and Type II inclusions consist of CaO-Al2O3-MgO and Al2O3-TiO2-CaO, respectively. Both types originate from the FeTi70R alloy. Type III clusters (Al2O3-MgO-CaO) are formed during an Al deoxidation of the Ni-based alloy. Type IV clusters (Al2O3-TiO2-CaO) formed from small inclusions, which are precipitated in local zones which contain high Ti and Al levels. These clusters are transformed to Type III clusters over time in the ladle. Finally, Type V clusters are typical TiN clusters. 

  • 6.
    Kellner, Hans
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    Karasev, A. V.
    Memarpour, A.
    Jönsson, P. G.
    Evolution of non-metallic inclusions from FeTi70R alloys during alloying of Fe-40Ni-20Cr steels2016Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, nr 11, s. 1461-1468Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the composition, size, and number of large non-metallic inclusions (>20μm) are investigated in a commercial refined FeTi70R alloy, which is used for deoxidation and alloying of different industrial high-quality steels. It is found that this ferroalloy contains different complex oxide inclusions, which sizes vary from 20 to 260μm. These different complex inclusions contain mostly CaO, SiO2, and TiOx. When adding FeTi70R alloy in the steel during the final stage of ladle treatment, these large size inclusions can significantly decrease the cleanliness and mechanical properties of steel. Therefore, the evolution and behavior of these inclusions after addition of this ferroalloy into the liquid iron or Fe-40Ni-20Cr steel are investigated in laboratory experiments. In addition, the results from the laboratory scale experiments are compared to results obtained from industrial heats using Alloy 825. A consideration of the evolution mechanism of large inclusions after an addition of a FeTi70R alloy helps to understand their behavior in the melt. It also helps to estimate their possible harmful effects on the quality of this steel grade during commercial production. 

  • 7.
    Kellner, Hans
    et al.
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik. KTH.
    Karasev, A. V.
    Sundqvist, O.
    Jönsson, P. G.
    Effect of the Stirring Mode on the Behavior of Al2O3–MgO Particles and Clusters during Ladle Treatment of Ni-based Alloy 8252017Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, nr 12, artikel-id 1700165Artikel i tidskrift (Refereegranskat)
  • 8.
    Lindgren, Michael
    Högskolan Dalarna, Akademin Industri och samhälle, Materialteknik.
    An improved model for the longitudinal peak strain in the flange of a roll formed U-channel developed by FE-analyses2007Ingår i: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 78, nr 1, s. 82-87Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Today one can find cold roll forming (CRF) products in many applications, for example vehicles, furniture and in the building industry. Though CRF is a well known sheet metal process, it is still not entirely understood due to the geometrically complex forming. There are several computer aided engineering (CAE) programs on the market that can assist the tool maker when designing a new CRF machine. However, they are often based on simple formulas when predicting the stress and the strain in the strip. The main objective of this study is to improve formulas for the longitudinal peak membrane strain and the deformation length when a U-channel is formed. These are important since they can be used to determine the number of forming steps and the distance between them. A twolevel factorial design is done using the finite element analysis to investigate which parameters affect the peak strain and the deformation length. The parameters are then used to build models for the peak strain and the deformation length.

1 - 8 av 8
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • chicago-author-date
  • chicago-note-bibliography
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf