| 1. |
- Easterling, K.E., et al.
(författare)
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Some recent developments in powder metallurgy in Sweden
- 1979
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Ingår i: Science of Sintering. - 0350-820X. ; 11:spec, s. 105-120
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Tidskriftsartikel (refereegranskat)abstract
- The authors concentrate on some recent scientific and technological developments in the two main areas of activity in Sweden, i.e. cemented carbides and steel powder metallurgy. They also give a few details of some interesting preliminary work on the hot isostatic pressing of silicon nitride and the development of sintered oxide containers for storing nuclear waste materials
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| 2. |
- Navara, E., et al.
(författare)
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Martensite formation in the haz of welded microalloyed steels
- 1982
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Ingår i: Scandinavian journal of metallurgy. - 0371-0459 .- 1600-0692. ; 11:4, s. 169-172
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Tidskriftsartikel (refereegranskat)abstract
- THE WELDING OF FINE GRAINED MICROALLOYED STEELS CAN BRING ABOUT CONSIDERABLE GRAIN GROWTH IN THE HEAT AFFECTED ZONE (HAZ) AND THIS IN TURN INCREASES THE POSSIBILITY OF MARTENSITE FORMATION. WELDING DIAGRAMS HAVE RECENTLY BEEN DEVELOPED FORPREDICTING THE AMOUNT OF GRAIN GROWTH IN THE HAZ OF VARIOUSSTEELS. THE OBJECT OF THE PRESENT WORK WAS TO STUDY THE AMOUNT OF MARTENSITE AS A FUNCTION OF GRAIN SIZE IN THE HAZ, AND TO SUPERIMPOSE THESE FIGURES ON THE WELDING DIAGRAM OF A NB-STEEL.
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| 3. |
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| 4. |
- Navara, Eric, et al.
(författare)
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Austenite formation in manganese-partitioning dual-phase steel
- 1986
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 2:12, s. 1196-1201
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Tidskriftsartikel (refereegranskat)abstract
- Manganese-containing ferritic-pearlitic steels have been studied after intercritical annealing for various times at temperatures of 700 and 725 degree C, during which austenite formation occurred at ferrite grain boundaries. Light and electron optical microscopy, and scanning transmission electron microanalysis and microdiffraction were employed for the study, in which both microstructural development and manganese redistribution were examined in detail. It was observed that the formation of austenite is associated initially with a migration of ferrite grain boundaries. It is proposed that this boundary migration is induced by manganese diffusion along the boundaries, and that this in turn provides the mechanism for rapidly transporting manganese to the growing austenite. On this basis, we find that austenite formation in these steels is associated with manganese-rich migrated ferrite boundaries, and is not dependent on the presence of cementite particles for nucleation
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| 5. |
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| 6. |
- Navara, E., et al.
(författare)
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Fracture toughness of P/M steels
- 1984
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Ingår i: International Journal of Powder Metallurgy and Powder Technology. - 0361-3488. ; 20:1, s. 33-43
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Tidskriftsartikel (refereegranskat)abstract
- A critical review of published work on the fracture toughness of sintered materials reveals differences in their behavior when compared with homogeneous materials. Nominal values of experimental results place porous materials at a disadvantage. This comparison is questioned by a deeper analysis of some relationships between fracture toughness and porosity, temperature, and specimen size. A first approximation model of the sintered body as an aggregate of necks is proposed which derives a requirement for inherent fracture toughness. (15 refs.)
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| 7. |
- Navara, E., et al.
(författare)
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Investigation of microstructural changes occurring during warm working of manganese partitioned dual phase steel
- 1990
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Ingår i: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 6:2, s. 151-155
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents results from studies using transmission and high resolution electron microscopy of as-received and warm worked manganese partitioned dual phase steel. A growing manganese enriched austenite grain shares two different boundaries with ferrite: (a) a stationary coherent boundary, replacing a stretch of the original ferrite/ferrite boundary, and (b) a migrating non-coherent boundary. This finding gives support to a previously described mechanism of the nucleation and growth of the manganese enriched austenite. The structure of the warm worked steel consists of recovered ferrite strengthened by substructure, and fine martensitic lathes separated by low angle boundaries which resulted from the transformation of deformed non-recrystallised austenite grains
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| 8. |
- Navara, Eric, et al.
(författare)
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The effect of alloying additions on the inclusion-matrix bond in oxide dispersion hardened alloys
- 1974
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Ingår i: IV. Medzinárodná Konferencia o Práskovej Metalurgii, Československá Socialistická Republika 1974, [Vysoké Tatry, 1 - 3.X]. - : Slovenska Vedeckotechnicka Spolocnost; Kosice. ; , s. 265-280
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Konferensbidrag (refereegranskat)abstract
- The factors contributing to strength and ductility of a series of Fe-Al2O3 dispersion hardened alloys are investigated. It is found that the bonding strength between the phases is of particular importance in alloys produced by powder metallurgy techniques, and this aspect of the problem is studied in detail using electron microscopy. The nature of bonding strength is then discussed and a model of diffuse interface postulated in order to account for improvements in the work of adhesion, caused by alloying the matrix with interface active elements. The diffuse-interface bond increases the strain required for the onset of void formation, and in extreme cases fracture occurs within the particles
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| 9. |
- Rubin, Per, et al.
(författare)
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Graphite Formation and Dissolution in Ductile Irons and Steels Having High Silicon Contents: Solid-State Transformations
- 2018
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Ingår i: Metallography, Microstructure, and Analysis. - New York : Springer. - 2192-9262 .- 2192-9270. ; 7:5, s. 587-595
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Tidskriftsartikel (refereegranskat)abstract
- Graphite formation in the solid state is both in ductile cast irons and in steels strongly promoted by high silicon contents above 3 wt.% Si. The matrix microstructure in austempered ductile iron can be further refined by secondary graphite if the austenitization, quench, and isothermal transformation into ausferrite are preceded by an austenitization at a slightly higher temperature followed by quench to martensite, resulting in higher carbon content than being soluble at the second austenitization temperature. Hypoeutectoid steels with high silicon contents can be rapidly graphitized, causing recrystallization of surrounding ferrite due to plastic deformation making room for less dense graphite. In rolled steels, the interface between manganese sulfide and steel matrix is the most common nucleation site. Voids are formed when graphite is partly or completely dissolved during austenitization in succeeding hardening heat treatments, but the mechanical properties can still be good if the graphite particles dissolved into voids are below 20 µm. Graphitized Si-solution strengthened ferritic steels may perform similar to free-cutting steels but with improved mechanical properties.
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| 10. |
- Rubin, Per, et al.
(författare)
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The effect of normalizing, intercritical annealing, and manganese partitioning, respectively, on the recrystallization behaviour of ferrite in a cold rolled carbon manganese structural steel
- 1990
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Ingår i: Recrystallization '90. - Warrendale, Pa : Minerals, Metals & Materials Society. - 0873391241 ; , s. 211-218
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Konferensbidrag (refereegranskat)abstract
- A commercial 0.16% carbon, 1.5% Mn structural steel was heat treated in three different ways, cold rolled and then recrystallized at temperatures between 500-600 deg C. The heat treatments were: normalizing at 920 deg C, 30 min, air cool; Mn partitioning treatment at 715 deg C, 112 h, air cool; dual-phase treatment, i.e. a short intercritical anneal at 750 deg C followed by quenching in water. All treatments produced massive two-phase structures, in which the second constituent was pearlite, Mn enriched martensite, and non-partitioned martensite, respectively. It is shown that the recrystallization rates of the ferrite in the steel samples, deformed 54%, differ significantly. The recrystallization temperature of the normalized and or the dual-phase steel is considerably higher than that of the Mn-partitioned dual-phase steel. The results of the experiments are discussed and some explanations of the steels' different recrystallization behaviours are suggested. Photomicrographs, Graphs. 7 ref.--AA
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