precipitazione cellulare in un acciaio austentico ad alto azoto: distribuzione degli elementi di lega e suoi effetti (Articolo in rivista)

Type
Label
  • precipitazione cellulare in un acciaio austentico ad alto azoto: distribuzione degli elementi di lega e suoi effetti (Articolo in rivista) (literal)
Anno
  • 2011-01-01T00:00:00+01:00 (literal)
Alternative label
  • A. Carosi 1; P. Deodati 2; M. Amati 3; S. Kaciulis 4; A. Mezzi 4; R. Montanari 2; L. Rovatti 2; N. Ucciardiello 2 (2011)
    precipitazione cellulare in un acciaio austentico ad alto azoto: distribuzione degli elementi di lega e suoi effetti
    in La Metallurgia Italiana
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • A. Carosi 1; P. Deodati 2; M. Amati 3; S. Kaciulis 4; A. Mezzi 4; R. Montanari 2; L. Rovatti 2; N. Ucciardiello 2 (literal)
Pagina inizio
  • 25 (literal)
Pagina fine
  • 31 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 5 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • (1) CSM (2) Università Tor Vergata (3) Sincrotrone di Trieste (4) CNR-ISMN (literal)
Titolo
  • precipitazione cellulare in un acciaio austentico ad alto azoto: distribuzione degli elementi di lega e suoi effetti (literal)
Abstract
  • The micro-analytical study of cellular precipitation in a high-nitrogen austenitic steel (HNS) was carried out by means of XPS, AES, photoelectron microscopy and EDS microanalysis. The use of photoelectron microscopy with high lateral resolution at the ESCA microscopy beamline of the Elettra synchrotron in Trieste permitted to determine the concentrations of N and Cr in the supersaturated matrix and inside the lamellae of the transformed zones. N in interstitial solution has a strong effect on solid solution strengthening, austenite stabilization and pitting corrosion resistance. Owing to their properties FINS can be used in different industrial fields, such as petrol plants, energy generation, production of paper and biomedicine. However, the precipitation of chromium nitrides, occurring in the temperature range of 550 - 1050 degrees C, can restrict the high-temperature applications of HNS. Cellular precipitation in the austenitic HNS after heat treatments has been already investigated by various techniques [1,2] and it was found that the transformation is accompanied by the modification of lattice parameter and micro-hardness. The results suggested that long-range diffusion of N from the untransformed gamma(s) matrix to the transformed regions may occur [2-4]. To complete the micro-structural study and verify if diffusion of N from gamma(s) matrix towards transformed regions really occurs, the experiments of AES and photoelectron microscopy have been carried out. This information was not available from the data of conventional XPS, where the diameter of investigated area is much higher than the inter-lamellar distance (about 250 nm) [1]. Moreover, internal friction (IF) and dynamic modulus measurements have been performed for investigating the distribution of N and other alloying elements on atomic scale. The examined HNS steel was prepared by Pressurized Electroslag Remelting; its nominal composition is reported in Tab. 1. The samples were isothermally heated at 850 degrees C in successive steps up to 23 hours. Auger spectra were collected by using an Escalab Mk 1I spectrometer (VG Scientific) equipped with 5-channeltron detection system and electron gun LEG 200, operated at 10 keV and 1-10 nA beam current. The spectra were acquired in the constant retard ratio (1 : 2) mode. The photoemission measurements with high lateral resolution were performed by means of the Scanning Photoelectron Microscopy (SPEM) at the Elettra synchrotron. The SPEM can be operated in imaging and spectroscopic modes with a spatial resolution of about 150 nm and resolution in energy of 0.2 eV, respectively. More experimental details on this technique have been reported previously [5,6]. IF and elastic modulus measurements were carried out by means of the VRA 1604 analyzer [7] on the reeds of 13.4 mm x 6.0 mm x 0.26 mm. The samples have been heated up to 800 degrees C at constant rate of 1.7 x 10(-2) degrees C s(-1). The modulus was determined from the resonance frequency f (Eq. 1) being m a constant, L and h length and thickness of the vibrating reed, rho material density. (literal)
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