Hardening evolution of AZ31B Mg sheet

Rate sensitivity and tension–compression asymmetry in AZ31B magnesium alloy sheet

“…From figure 4a-c, it is observed that the shape of the stress-strain curves is concave upwards (S-shape) for the inplane compressive loading at all strain rates. Such a stress-strain response is consistent with the predominance of [10][11][12] twinning that takes place during the first stages of deformation, leading to an 86 • rotation of the c-axes (which are perpendicular to compression axis in most grains before deformation) which brings them into alignment with the compression axis. This initial twinning is followed by strong strain-hardening behaviour at larger strains owing to the subsequent operation of non-basal slip [4,7,8].…”

“…Extensive research has been carried out on the plastic deformation behaviour of magnesium alloys, but most studies have focused on quasi-static loading conditions [12][13][14]. The high strain rate behaviour is of great interest to the automotive and aircraft sectors, because the dynamic response of components must be known to support design and simulation for severe loading conditions, such as crash or impact [15,16].…”

Continuum modeling of the response of a Mg alloy AZ31 rolled sheet during uniaxial deformation

“…The operation of hc + ai slip during the last stages of deformation has been reported under such conditions by Yi et al (2006). Here too, some other investigations report that strain is, instead, accommodated by the activation of other mechanisms, such as a combination of basal and hai pyramidal slip (Mordike and Ebert, 2001), the increasing activity of basal slip (Lou et al, 2007) or the simultaneous operation of basal slip and double twinning (Kelley and Hosford, 1968b).…”

“…In particular, at this point it is key to develop simulation models that, supported by the experimental data available, can predict of the response of Mg alloys under different service conditions. The deformation mechanisms of Mg and Mg alloys that are operative at low strain rates have been extensively investigated over the past years (Couling et al, 1959;Kocks and Westlake, 1967;Kelley and Hosford, 1968a;Couret and Caillard, 1985;Chin and Mammel, 1970;Yoo, 1981;Vagaralia and Langdon, 1981;Zelin et al, 1992;Munroe and Tan, 1997;Agnew et al, 2001;Watanabe et al, 2001;Barnett, 2001;Agnew et al, 2003;Galiyev et al, 2003;Koike et al, 2003;Barnett, 2003;Gehrmann et al, 2005;Barnett et al, 2004a;Agnew and Duygulu, 2005;del Valle et al, 2005;Keshavarz and Barnett, 2006;Meza-García et al, 2007;Barnett, 2007;del Valle and Ruano, 2007;Al-Samman and Gottstein, 2008;Chino et al, 2008;Jain et al, 2008;Hutchinson et al, 2009;Ball and Prangnell, 1994;Lou et al, 2007). Slip in hexagonal close packed (HCP) metals may take place along the h11 20i (hai) direction on basal and non-basal (f10 10g-prismatic, f10 11g-pyramidal) planes.…”

“…Although widely spread values have been reported for the critical resolved shear stress (CRSS) in different slip and twinning systems (Chin and Mammel, 1970;Agnew et al, 2001Agnew et al, , 2003Barnett, 2003;Agnew and Duygulu, 2005;Lou et al, 2007), it is generally accepted that, for polycrystals, CRSS basal < CRSS twinning < CRSS prismatic 6 CRSS pyramidal . In agreement with this trend, earlier studies reported that slip on basal planes and f10 12g twinning (so called extension twinning) are the main deformation mechanisms during uniaxial deformation at low temperatures and low strain rates in randomly oriented Mg polycrystals of conventional grain sizes ($10 À 50 lm) (Couling et al, 1959;Kocks and Westlake, 1967;Kelley and Hosford, 1968a;Couret and Caillard, 1985;Chin and Mammel, 1970;Yoo, 1981).…”