1,721,153 research outputs found
Quantification of the effect of early microstructural degradation during creep of 9Cr–1Mo–NbV steels at 600 °C
No full textConstitutive equations in creep of Mg–Al alloys
No full textThe creep response of commercial Mg–Al alloys for die-casting was described by taking into account the distinctive microstructure consisting of α-Mg primary grains and a divorced eutectic formed by supersaturated α-Mg and β-Mg17Al12 typical of these materials. The α-Mg grains were assimilated to soft zones in a composite reinforced by hard zones rich in precipitates, the latter being the grain boundary regions of supersaturated α-Mg and β-Mg17Al12. Constitutive equations correlating minimum creep rate, applied stress and temperature were derived for dilute Mg–Al solid solutions and used to calculate the forward stress acting in soft and hard regions, respectively, on the assumption that both creep with a similar strain rate. The role of the particles was then expressed by a threshold stress; as a consequence, Si addition resulted in a substantial increase in the threshold stress in the hard zones, a mechanism that explains the reduction in minimum creep rate observed in the high-temperature low-stress regime in Mg–Al–Si compared with Mg–Al–Zn alloy
Microstructure-based assessment of creep rupture strength in 9Cr steels
No full textA microstructure-based model to assess the long-term creep strength in 9Cr steels is proposed. The
model takes into account a number of different key issues, including the presence and evolution of the
most important families of precipitates (M23C6, MX, Laves and Z phases), the subgrain recovery process,
the different strengthening mechanisms (solid solution strengthening and particle strengthening), and is
able to give realistic values of the long-term creep strength in P9, P91 and P911 steels. If properly tuned
to describe the mid/long-term precipitation of the Z-phase, and the concurrent dissolution of MX
precipitates, the model can also predict the sigmoidal behaviour which leads to the early rupture of
single heats of P91 steel
Interpretation of creep behaviour of dispersion strengthened Al-Fe-V-Si alloys in terms of detachment mechanisms: an overview
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Effect of microstructural instability on creep response: Case studies [Ruolo dell'instabilità microstrutturale nel creep: Casi di studio]
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