Propiedades mecánicas y mecanismos de deformación en aleaciones del sistemas Fe-xMn-3,2Al0,2C (12 ≤ x ≤ 43)

Revista de Metalurgia (Impact Factor: 0.29). 05/1998; 34(Extra):362-366. DOI: 10.3989/revmetalm.1998.v34.iExtra.772
Source: DOAJ


Microstructure and mechanical properties of Fe-xMn-3,2Al-0,23C alloys with 12 ≤ x ≤ 43 (mass %) at 77 and 290 K have been studied to determine the mechanisms controlling plastic deformation. Austenitic alloys (Mn ≥ 22) show an increase of elongation to failure with decreasing temperature of testing (inverse ductility). This behavior has been related to formation of deformation twins, which is favored at 77 K. Alloys with manganese content lower than 17 % present a two-phase microstructure (α' + γ). The martensite volume fraction increases as the manganese content decreases. These alloys show a loss of ductility, especially at 77 K. In contrast to asutenitic alloys, this different mechanical behavior has been associated with a TRIP mechanism (transformationinduced plasticity).Se han estudiado la microestructura y las propiedades mecánicas a 77 y 290 K de una serie de aleaciones Fe-xMn-3,2Al-0,23C con 12 ≤ x ≤ 43 (% en masa) con objeto de determinar los mecanismos que controlan la deformación plástica. Se ha comprobado que, en las aleaciones con estructura austenítica (Mn ≥ 22), el alargamiento a rotura aumenta al disminuir la temperatura de ensayo (ductilidad inversa). Este comportamiento se ha relacionado con un proceso de deformación por maclaje favorecido a 77 K. Las aleaciones con contenidos de manganeso < 17 % presentan una estructura bifásica (α' + γ), siendo mayor la fracción de volumen de martensita a medida que disminuye la concentración de manganeso. Estas aleaciones presentan una disminución del alargamiento a rotura especialmente a 77 K. El diferente comportamiento mecánico con respecto al de las aleaciones austeníticas se asocia a un proceso de transformación a martensita inducida por deformación (TRIP).

Download full-text


Available from: J. Chao, Aug 04, 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Samples from the Fe0.45Mn0.25Al0.30 system were prepared by mechanical alloying during 4, 8, 12, 16, 22 and 24 h by using two different powder-mass-to-ball-mass ratios of: 1:7.5 and 1:4. X-ray diffraction (XRD) characterization reveled that samples with 1:7.5 ratios consolidate in a ternary Fe-Mn-Al ?-Fe solid solution at 8 h (chemical mixing time) and those with 1:4 ratios after more than 12 h milling. Mössbauer effect studies (MS) in conjunction with XRD studies show, in samples with a 1:7.5 ratio, a paramagnetic site and a hyperfine field distribution (HFD) for 4 h and only a paramagnetic site for 8 h or more. Therefore, the solid solution is paramagnetic in the stable state. Similar results were obtained for 1:4 ratios, but the paramagnetic site was observed after 16 h or more. Mössbauer studies at low temperatures of the sample milled for 12 h and a 1:4 ratio demonstrate that this sample presents a re-entrant spin-glass to the ferromagnetic transition (RSG-F) at T k = 45 K. This RSG-F transition was proven by an ac magnetic susceptibility measurement, appearing at T = 30 K.
    physica status solidi (b) 05/2006; 243(6):1390-1399. DOI:10.1002/pssb.200541342 · 1.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this paper is to investigate the isothermal behavior of Fe–27.3Mn–7.6Al–C–6.5Cr–0.25Si–0.88Mo (Mo(0)) and Fe–27.3Mn–7.6Al–1.0C–6.5Cr–0.25Si (Mo(1)) alloys and compare it against Fe–9Cr–1Mo (FCR) commercial alloy. The experiments were carried out at 600°C, 700°C, 750°C and 850°C, each one during 72h in static air. The oxidation kinetics was measured as a function of time using a Thermogravimetry analyzer (TGA). The structure and composition of the oxide scale were characterized by X-ray diffraction (XRD) and Integral Conversion Electron Mössbauer Spectroscopy (CEMS). The TGA results show that at all oxidation temperatures the sample FCR exhibit the lowest kinetic corrosion and the lowest weight gain, whereas Mo(0) the highest. By CEMS technique it were found a broad magnetic sextet, which has been fit by one hyperfine field distribution with mean hyperfine field characteristic to ferritic/martensite phase, one Fe3 +  doublet and one singlet for the Mo(0) and Mo(1) alloys. Samples oxidized at highest temperatures exhibit a strong paramagnetic line, probably due that the Cr or Mn oxides may be enriched on the surface. Then, the magnetic phase can be converted partially into austenite phase at highest temperatures.
    05/2009: pages 1129-1134;