| 1. |
- Adineh, Morteza, et al.
(author)
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Microstructure, mechanical properties and machinability of Cu-Zn-Mg and Cu-Zn-Sb brass alloys
- 2019
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In: Materials Science and Technology. - : TAYLOR & FRANCIS LTD. - 0267-0836 .- 1743-2847. ; 35:12, s. 1504-1514
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Journal article (peer-reviewed)abstract
- Lead-free alloys have attracted great attentions recently due to the toxic nature of lead for the human body. In this study, low amounts of Mg and Sb were added to the Cu65-Zn35 brass and microstructure, mechanical properties and machinability of samples were compared to Cu65-Zn35 brass. Both Mg and Sb led to the promotion of beta ' phase as well as the formation of new ternary copper rich intermetallic particles. It was found that these particles had a significant role in the reduction of the ultimate tensile strength, toughness, work hardening and elongation while increasing the hardness of samples. Results of machinability evaluation of samples showed that the cutting forces were decreased significantly and morphology of chips were improved compared to Cu65-Zn35 brass sample.
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| 2. |
- Andersson, Joel, 1981-, et al.
(author)
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Effect of Different Solution Heat Treatments on the Hot Ductility of Superalloys : Part 3 - Waspaloy
- 2013
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 29:1, s. 43-53
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Journal article (peer-reviewed)abstract
- The susceptibility to heat affected zone cracking of Waspaloy has been investigated in terms of its hot ductility, measured as the reduction of area (RA). Gleeble testing with on-heating as well as on-cooling test cycles was carried out to illuminate the influence of different 4 h solution heat treatments between 996 and 1080°C. A ductility maximum of between 80 and 90%RA was found at 1050–1100°C for all conditions in the on-heating tests. Although the different heat treatment conditions showed similar macrohardness, the particle size and distribution of the γ′ and M23C6 phases differed, which significantly affected the on-heating ductility in the lower temperature test region. The ductile to brittle transition was initiated at 1100°C in the on-heating testing with indications of grain boundary liquation at the higher test temperatures. Ductility recovery, as measured in the on-cooling tests from 1240°C, was very limited with <30%RA for all conditions and test temperatures except for the 1080°C/4 h treatment, which exhibited 60%RA at 980°C.
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| 3. |
- Andersson, Joel, 1981-, et al.
(author)
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Effect of solution heat treatments on superalloys : Part 1 – alloy 718
- 2012
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In: Materials Science and Technology. - : Taylor & Francis Group. - 0267-0836 .- 1743-2847. ; 28:5, s. 609-619
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Journal article (peer-reviewed)abstract
- The hot ductility as measured by Gleeble testing of Alloy 718 at four different solution heat treatments (954°C/15 h, 954°C/1 h, 982°C/1 h and 1050°C/3 h+954°C/1 h) has been investigated. It is concluded that constitutional liquation of NbC assisted by δ phase takes place and deteriorates the ductility. Parameters established by analysing the ductility dependence on temperature indicate a reduced weldability of the material in the coarse grain size state (ASTM 3) while indicating an increased weldability when containing a large amount of δ phase due to a grain boundary pinning effect. The accumulation of trace elements during grain growth at the highest temperature is believed to be the cause for the observed reduced on-cooling ductility.
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| 4. |
- Andersson, Joel Håkan, 1981, et al.
(author)
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Effect of different solution heat treatments on hot ductility of superalloys Part 2-Allvac 718Plus
- 2012
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In: Materials Science and Technology. - : Taylor & Francis Group. - 1743-2847 .- 0267-0836. ; 28:6, s. 733-741
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Journal article (peer-reviewed)abstract
- The hot ductility of Allvac 718Plus for different solution heat treatments (954 degrees C-15 h, 954 degrees C-1 h, 982 degrees C-1 h and 1050 degrees C-3 h+954 degrees C-1 h) has been investigated using Gleeble testing. Substantial variations in the microstructure among the heat treatments affected the Gleeble test hot ductility only to a very limited extent. Constitutional liquation of the NbC phase was found to be the main cause for the poor ductility at high testing temperatures in the on-heating cycle as well as at the lower temperatures on-cooling. Grain boundary delta phase was seen to assist the constitutional liquation of the NbC phase. Based on established evaluation criteria for Gleeble ductility testing, a ranked indicator for weldability is suggested.
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| 5. |
- Andersson, Joel Håkan, 1981, et al.
(author)
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Effect of solution heat treatments on superalloys Part 1 - alloy 718
- 2012
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In: Materials Science and Technology. - : Informa UK Limited. - 1743-2847 .- 0267-0836. ; 28:5, s. 609-619
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Journal article (peer-reviewed)abstract
- The hot ductility as measured by Gleeble testing of Alloy 718 at four different solution heat treatments (954 degrees C/15 h, 954 degrees C/1 h, 982 degrees C/1 h and 1050 degrees C/3 h+954 degrees C/1 h) has been investigated. It is concluded that constitutional liquation of NbC assisted by delta phase takes place and deteriorates the ductility. Parameters established by analysing the ductility dependence on temperature indicate a reduced weldability of the material in the coarse grain size state (ASTM 3) while indicating an increased weldability when containing a large amount of delta phase due to a grain boundary pinning effect. The accumulation of trace elements during grain growth at the highest temperature is believed to be the cause for the observed reduced on-cooling ductility.
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| 6. |
- Andersson-Östling, Henrik C.M., et al.
(author)
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Influence of phosphorus, sulphur and grain size on creep in pure copper
- 2009
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847.
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Journal article (other academic/artistic)abstract
- Uniaxial creep tests have been performed at 175 °C to study the influence of phosphorus, sulphur and grain size on the creep properties of oxygen free copper. Copper with no phosphorous content and copper with 2000 μm grain size showed lower creep strength and ductility than the reference material which contained 58 ppm phosphorous and had 350 μm average grain size. Phosphorous content of 29 and 106 ppm showed no difference in relation to the reference material, and neither did grain sizes of 100 and 800 μm average grain size. 6 or 12 ppm sulphur did not affect the creep properties at all. The main creep rupture mechanisms were found to be cavitation and microcracking at the grain boundaries. The observed influence of P on creep is consistent to previously published models both with respect to creep rate and creep ductility.
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| 7. |
- Andersson-Östling, Henrik C.M., et al.
(author)
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Testing and modelling of creep in copper friction stir welds
- 2009
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847.
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Journal article (other academic/artistic)abstract
- Specimens cut from friction stir welds in copper canisters for nuclear waste have been used for creep experiments at 75°C. The specimens were taken from a cross-weld position as well as heat affected zone and weld metal. The weld specimens exhibited shorter creep lives than the parent metal specimens by a factor of three in time. The cross weld and HAZ specimens were shorter by an order of magnitude when compared to the weld metal. The creep exponent was in the interval 50 to 69 implying that the material was well inside the power-law breakdown regime. The ductility properties expressed as reduction in area were not significantly different in the weld zones and all the rupture specimens demonstrated valu esexceeding 80%. The stationary creep rate for the parent metal was consistent with a previously developed model. The primary creep was successfully modelled. Weld reduction factors have been obtained by comparing the results from base metal tests and weld tests. Measured values at 75 °C for are about 6% for friction stir welds and 14% for electron beam welds.
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| 8. |
- Bakshi, S. Das, et al.
(author)
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Dry rolling/sliding wear of nanostructured pearlite
- 2015
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 31:14, s. 1735-1744
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Journal article (peer-reviewed)abstract
- The dry rolling-sliding wear behaviour of pearlite that has an interlamellar spacing of just 85 nm has been characterised. Its wear resistance is found to be comparable to that of much harder bainitic steels. Microstructural observations indicate that there is substantial plastic deformation of both ferrite and cementite components of pearlite in the vicinity of the wear surface. Plasticity is not expected from Hertzian analysis that assumes a smooth contact surface. Instead, it is likely to be a consequence of exaggerated stresses due to surface roughness. The material remains ductile to shear strains in the order of 4. Diffraction data indicate that the coherent domain size is reduced to about half the interlamellar spacing and that some of the cementite may dissolve and contribute to the expansion of the lattice parameter of ferrite
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| 9. |
- Barbaro, F. J., et al.
(author)
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Formation of acicular ferrite at oxide particles in steels
- 1989
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In: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 5:11, s. 1057-1068
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Journal article (peer-reviewed)abstract
- Experimental steels similar in composition to structural grades were prepared from weld metal deposits to study the formation of acicular ferrite under conditions experienced in the heat affected zone for a range of welding processes. The formation of acicular ferrite under these conditions is found to be dependent on the presence of a suitable distribution of oxide inclusions > 0·4 μm in size. The characteristics and proportion of acicular ferrite in the microstructure also depend on the prior austenite grain size and cooling rate. The relationship between these factors is presented in a simplified quantitative model, which is supported by data from limited welding trials. Metallographic observations suggest that acicular ferrite forms in two stages. The first involves the formation of relatively large primary acicular ferrite plates by multiple nucleation at intragranular inclusion sites, and the second involves the formation of many smaller acicular ferrite grains that grow sympathetically from the primary plates.
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| 10. |
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| 11. |
- Bratberg, Johan, et al.
(author)
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Diffusion simulations of MC and M7C3 carbide coarsening in bcc and fcc matrix utilising new thermodynamic and kinetic description
- 2008
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In: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 24:6, s. 695-704
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Journal article (peer-reviewed)abstract
- A new thermodynamic database has been combined with an existing kinetic database to perform coarsening simulations in ternary systems including MC and M7C3 carbides in an fcc matrix. The kinetic database was revised taking into consideration the new experimental information on the Fe-Cr-V-C system obtained in the present work, and available experiments on the ternary Fe-Cr-C and Fe-V-C systems. After revision the agreement between experimental results and simulations was satisfactory. It was found that the interfacial energy of M7C3 was twice as large as that of the MC carbide. The calculations for commercial steels with 6 alloy elements gave results in satisfactory agreement with new experimental measurements. The present coarsening simulations use the calculated equilibrium state and the observed particle sizes as the state for the start of the simulations. All the simulations were performed with the DICTRA software.
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| 12. |
- Bratberg, Johan, et al.
(author)
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Diffusion simulations of MC and M7C3 carbide coarsening in bcc and fee matrix utilising new thermodynamic and kinetic description
- 2008
-
In: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 24:6, s. 695-704
-
Journal article (peer-reviewed)abstract
- A new thermodynamic database has been combined with an existing kinetic database to perform coarsening simulations in ternary systems including MC and M7C3 carbides in an fee matrix. The kinetic database was revised taking into consideration the new experimental information on the Fe-Cr-V-C system obtained in the present work, and available experiments on the ternary Fe-Cr-C and Fe-V-C systems. After revision the agreement between experimental results and simulations was satisfactory. It was found that the interfacial energy of M7C3 was twice as large as that of the MC carbide. The calculations for commercial steels with 6 alloy elements gave results in satisfactory agreement with new experimental measurements. The present coarsening simulations use the calculated equilibrium state and the observed particle sizes as the state for the start of the simulations. All the simulations were performed with the DICTRA software. © 2008 Institute of Materials, Minerals and Mining.
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| 13. |
- Chen, Kaixuan, et al.
(author)
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Effects of solute content on microstructure of nano precipitate-fine grain synergistically reinforced copper alloys
- 2020
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In: Materials Science and Technology. - : Taylor and Francis Ltd.. - 0267-0836 .- 1743-2847.
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Journal article (peer-reviewed)abstract
- Alloying of Fe, Co was reported to tailor microstructure of copper alloys into a nanoprecipitate-fine grain (NPFG) structure, i.e. nano-sized iron-rich precipitates dispersed inside refined grains. Here, we investigate the solute effect of Sn, Zn on NPFG structure in as-cast copper samples. Mechanisms are proposed to account for the solute effect on precipitate and grain features. Solutes restrict coarsening but facilitate undesirable morphology transition from spherical to angular of iron-rich precipitates. Meantime, solutes allow more precipitates to be active in the nucleation of copper and consequently induce finer grains. Minor Sn is added to optimise NPFG structure and leads to an excellent strength–ductility combination in Cu–1.5Fe–0.1Sn (wt-%) alloy. This work provides a solute-alloying strategy to achieve desired mechanical properties in metals.
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| 14. |
- Chen, Kaixuan, et al.
(author)
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Precipitates-interaction capture of nano-sized iron-rich precipitates during copper solidification
- 2019
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In: Materials Science and Technology. - : Taylor & Francis. - 0267-0836 .- 1743-2847. ; 35:9, s. 1028-1037
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Journal article (peer-reviewed)abstract
- Nano-sized iron-rich precipitates reinforced copper alloys achieve excellent mechanical properties. Capture mechanism of iron-rich precipitates into copper grains during solidification was described but needs further validation. Here, Cu-1.5Fe-0.5Co (wt-%) alloy is fabricated by gravity casting. Iron-rich precipitates in nano and submicron scale (mostly < 100 nm) are well dispersed in copper grain interior. Traditional pushing/engulfment transition (PET) models are used to interpret the capture process of iron-rich precipitates during copper solidification, but all fail to match the experimental results. The precipitates-interaction capture mechanism is most reasonable for describing the capture process.
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| 15. |
- Claesson, Erik, et al.
(author)
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The effect of alloying elements on the corrosion resistance of brass
- 2016
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In: Materials Science and Technology. - : Taylor and Francis Ltd.. - 0267-0836 .- 1743-2847. ; 32:17, s. 1794-1803
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Journal article (peer-reviewed)abstract
- A systematic study has been performed on the effect of alloying elements arsenic (As), antimony (Sb) and phosphorus (P) on the dezincification resistance of α-phase in brass. The result showed that P formed particles with Al and Fe already at relatively high temperatures, leaving no P in solid solution and thus no protection against dezincification. Arsenic only formed particles at lower temperatures and offers a satisfactory protecting. However, with increasing As levels grain boundary attack was observed. Samples alloyed with Sb show a satisfactory resistance to dezincification and no grain boundary attack. Finally, a combination of As and Sb at low alloying levels provided an excellent dezincification resistance for brass containing typical impurity levels. This paper is part of a Themed Issue on Brass Alloys. © 2016 Swerea KIMAB.
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| 16. |
- Cong, DY, et al.
(author)
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Crystal structures and textures of hot forged Ni48Mn30Ga22 alloy investigated by neutron diffraction technique
- 2005
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 21:12, s. 1412-1416
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Journal article (peer-reviewed)abstract
- A ferromagnetic shape memory alloy of Ni48Mn30Ga22 prepared by induction melting was successfully hot forged. Strong textures and a large anisotropy of in plane plastic flow were developed during the hot forging process. The crystal structures, both in austenitic and martensitic states, were investigated by means of neutron powder diffraction technique. The result suggests that Ni48Mn30Ga22 has a cubic L2(1) Heusler structure at room temperature, the same as that in the stoichiometric Ni2MnGa. When cooled to 243 K, the Ni48Mn30Ga22 alloy changes into a seven layered orthorhombic martensitic structure. No substantial change of the neutron diffraction pattern was observed upon further cooling to 19 K, indicating that there is no intermartensitic transformation in the investigated alloy, which is different from the transformation processes in the Ni-Mn-Ga alloys with higher martensitic transformation temperatures.
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| 17. |
- Cvetkovski, Krste, 1983, et al.
(author)
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Rapid thermomechanical tempering of iron–carbon martensite
- 2014
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In: Materials Science and Technology. - 1743-2847 .- 0267-0836. ; 30:14, s. 1832-1834
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Journal article (peer-reviewed)abstract
- Tempering of martensite under simultaneous compressive stress has been studied within thetemperature range of 20–400 deg C. Resistive heating was utilised to obtain rapid heating and coolingcycles of a few seconds. Material was obtained from a medium carbon pearlitic railway wheelsteel, quench hardened to obtain martensitic structure. Above approx 150 deg C dilatation effectswere observed below the global yielding point of the material. Microstraining around dislocationsin the body centred tetragonal crystallographic structure or viscous flow at higher temperatureswas a probable explanation to this material behaviour. Hence, external stress may have animportant influence on the tempering progression of martensitic steel. The trials also showed thattempering of martensite progresses fast, is near instantaneous and is independent of thepresence of external stress or not.
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| 18. |
- Cvetkovski, Krste, 1983, et al.
(author)
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Thermal degradation of pearlitic steels: influence on mechanical properties including fatigue behaviour
- 2011
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In: Materials Science and Technology. - 1743-2847 .- 0267-0836. ; 27:3, s. 648-654
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Journal article (peer-reviewed)abstract
- With the aim to predict the durability of railway wheels, thermomechanical damage was studiedfor two steels with different alloying levels of silicon and manganese in the temperature range of500–725uC. Softening caused by cementite spheroidisation in pearlite leads to changes in themechanical behaviour and an accompanying decrease in fatigue lifetimes. It was found thathigher contents of Si and Mn lead to better resistance to softening of both virgin and plasticallydeformed material. Correspondingly, the high Si–Mn alloyed steel loses much less in fatiguelifetime than the lower alloyed steel.
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| 19. |
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| 20. |
- DAS, D.K., et al.
(author)
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High temperature oxidation behaviour of directionally solidified nickel base superalloy CM–247LC
- 2003
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In: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 19:6, s. 695-708
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Journal article (peer-reviewed)abstract
- The present paper describes the isothermal and cyclic oxidation behaviour of the technologically important nickel base directionally solidified superalloy CM-247LC in air in the temperature range 1000-1200°C. This superalloy behaves as a transition nickel base alloy under isothermal oxidation conditions and exhibits a fairly long transient oxidation period (~20 h at 1100°C). Irrespective of the temperature of exposure and nature of oxidation (isothermal or cyclic), a composite oxide scale develops on CM-247LC. While the outer portion of the oxide scale consists of either spinel (NiAl2O4) or a mixture of spinel and NiO, depending on oxidation temperature, the inner portion is always constituted of alumina. Beyond the transient period, the alloy is found to follow parabolic oxidation kinetics. The oxide layer that forms is invariably very non-uniform in thickness, and is dispersed with two types of oxide particles. While tantalum rich oxide particles are found scattered in the outer zone of the oxide layer, hafnium rich oxide particles lie close to the oxide/metal interface. Results also reveal that the nature of oxidation associated with the CM-247LC superalloy causes entrapment of metal islands in the oxide layer.
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| 21. |
- Das, Yadunandan B., et al.
(author)
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The influence of temperature on deformation-induced martensitic transformation in 301 stainless steel
- 2018
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In: Materials Science and Technology. - : Taylor & Francis Group. - 0267-0836 .- 1743-2847. ; 34:17, s. 2114-2125
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Journal article (peer-reviewed)abstract
- Deformation-induced martensitic transformations are increasingly being used to create desirable mechanical properties in steels. Here, the kinetics of the deformation-induced martensitic transformation is investigated at 300, 263, 223, 173 and 100 K using in situ neutron diffraction during tensile loading. The results from these experiments show a distinct change in the transformation behaviour between 300 K and the tests conducted at 263 K and below, causing a difference in martensite structure. The difference in transformation kinetics is correlated to the suppression of slip at low temperatures, as evidenced using diffraction peak intensity analysis for different grain families and corroborated using transmission electron microscopy. A direct correlation between the deformation-induced martensite fraction and the work-hardening rate is shown.
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| 22. |
- Desai, Ashish, et al.
(author)
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Numerical and experimental investigation on AZ91 friction stir welding joints : mechanics, properties
- 2023
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In: Materials Science and Technology. - : Taylor & Francis Group. - 0267-0836 .- 1743-2847. ; 39:17, s. 1-15
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Journal article (peer-reviewed)abstract
- The present endeavour is to evaluate numerically and experimentally the influence of friction stir welding (FSW) parameters on peak temperatures, microstructures and mechanical properties of AZ91 magnesium alloy joints. A full 3D finite element ABAQUS model was developed to simulate the temperature distribution along the joint line. There from, a total of nine differ-ent parametric combinations were derived for experimentations. Important insights relating to the material flow patterns and grain morphologies observed while altering the processing parameters have been elaborated. The parametric influence on the peak temperatures, grain morphologies, intermittent phases, tensile strength, and hardness are discussed through several mechanisms. Remarkably, the specimens prepared with the highest tool rotation speeds exhibited superior properties owing to several strengthening mechanisms.
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| 23. |
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| 24. |
- Fredriksson, Hasse, et al.
(author)
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Theory of hot crack formation
- 2005
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In: Materials Science and Technology. - : Informa UK Limited. - 0267-0836 .- 1743-2847. ; 21:5, s. 521-529
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Journal article (peer-reviewed)abstract
- The hot crack sensitivity in metals is suggested to be caused by the supersaturation of vacancies created during the solidification process. Equations have been derived to predict the nucleation and growth of cracks by the condensation of vacancies. The transition temperature from brittle to ductile fracture was found to be related to the decrease in the supersaturation of vacancies due to an annealing process. The hot crack sensitivity was observed to be related to the supersaturation of vacancies, the diffusion rate, and the structure coarseness. The effect of surface active elements such as phosphorous and sulphur in steel alloys is discussed.
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| 25. |
- Frisk, Karin
(author)
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Simulation of precipitation of secondary carbides in hot work tool steels
- 2012
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In: Materials Science and Technology. - 0267-0836 .- 1743-2847. ; 28:3, s. 288-294
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Journal article (peer-reviewed)abstract
- Precipitation of secondary carbides in hot work tool steels during tempering heat treatments has been investigated using simulations based on a thermodynamic description coupled with kinetic parameters through multicomponent nucleation and growth models. The simulations reproduce the measured effects of steel composition on the precipitation of secondary carbides. Both Si and V increase the volume fraction of fine secondary carbides precipitated during tempering provided that the austenitising temperature is adjusted to give the same fraction of retained primary carbides. The most important effect of Si in 5%Cr steels is its influence on the primary carbide stability at austenitisation temperatures, but increasing the V contents has a strong effect on the fraction of secondary carbides, without increasing the size, and can thus improve the yield strength. The most critical input to the calculations is the thermodynamic description of the individual phases. © 2012 Institute of Materials, Minerals and Mining.
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