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Modelling Grain Growth Kinetics in Steels

Napoli G., Di Schino A.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 2

839--844

Steel is a versatile material that has found widespread use because of its mechanical properties, its relatively low cost, and the ease with which it can be used in manufacturing process such as forming, welding and machining. Regarding to mechanical properties are strongly affected by grain size and chemical composition variations. Many industrial developments have been carried out both from the point of view of composition variation and grain size in order to exploit the effect of these variables to improve the mechanical proprieties of steels. It is also evident that grain growth are relevant to the mechanical properties of steels, thus suggesting the necessity of mathematical models able to predict the microstructural evolution after thermo cycles. It is therefore of primary importance to study microstructural changes, such as grain size variations of steels during isothermal treatments through the application of a mathematical model, able in general to describe the grain growth in metals. This paper deals with the grain growth modelling of steels based on the statistical theory of grain growth originally developed by Lücke [1] and here integrated to take into account the Zener drag effect and is therefore focused on the process description for the determination of the kinetics of grain growth curves temperature dependence.

Tectonic evolution of the Sicilian Thrust System (central Mediterranean)

Napoli G., Nigro F., Renda P., Ślqczka A., Favara R.

Geological Quarterly

2012

Vol. 56, No. 4

579--600

The Sicilian Thrust System (STS) is a south-verging (Africa-verging) fold-and-thrust belt including a Mesozoic-Paleogene sedimentary sequence. This thrust stack owes its origin to the deformation of pre-orogenic strata deposited in different palaeogeographic domains belonging to passive margins of the African plate. The STS was deformed during the Neogene, following the closure of the Tethys Ocean and the continental collision between the Sardo-Corso Block and the north Africa margins. The thrust pile was detached from the underlying basement during the Miocene-Pleistocene. The regional-scale structural setting recognized allows us to reconstruct the tectonic evolution of the STS as follows: I - piggy-back thrusting from the Late Oligocene to the Langhian, inducing the building of the Inner Sicilian Chain (ISC); II - piggy-back thrusting from the Langhian to the Tortonian, inducing the formation of the Middle Sicilian Chain (MSC); III - generalized extensional deformation in the chain-foredeep-foreland system from the Tortonian to the Early Pliocene; IV-a new onset of piggy-back thrusting after the Early Pliocene allowed the building of the Outer Sicilian Chain and out-of-sequence thrusting in the previously developed ISC and MSC.