A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates

Abstract

a b s t r a c tThis study presents a constitutive model for steels exhibiting SIMT, based on previous sem inal works, and the corresponding methodology to estimate their parameters. The model includes temperature effects in the phase transformation kinetics, and in the softening of each solid phase through the use of a homogenization technique. The model was validated with experimental results of dynamic tensile tests on AISI 304 sheet steel specimens, and their predictions correlate well with the experimental evidence in terms of macroscopic stress strain curves and martensite volume fraction formed at high strain rates. The work shows the value of considering temperature effects in the modeling of metastable austen itic steels submitted to impact conditions. Regarding most of the works reported in the lit erature on SIMT, modeling of the martensitic transformation at high strain rates is the distinctive feature of the present paper.

Dynamic necking in materials with strain induced martensitic transformation

“…The constitutive model for the metastable austenitic stainless steel uses Huber-Mises plasticity and the features related to martensitic transformation are based on the previous works of Olson and Cohen (1975), Stringfellow et al (1992) and Zaera et al (2012Zaera et al ( , 2013. Since inception and development of necks in a slender bar will be analyzed using linear stabilityderived within a 1D framework -and finite element simulations -developed within a 3D framework -, both onedimensional and three-dimensional approaches will be presented, on the understanding that both coincide in their essential features and that, for a uniaxial state of stress, the 3D model provides the same results as its 1D counterpart.…”

“…There are other methods allowing to obtain homogeneous properties for multiphase materials in a more rigourous way, such as the procedure described in Papatriantafillou et al (2006) and Zaera et al (2012), but the one proposed above is especially suitable within the frame of the linear stability approach that will be described and used later. Additionally, the yield stress of both austenite and martensite have been considered constant, neglecting any functional dependence on strain, strain rate and temperature.…”

“…Table 1 shows the values of the model parameters for the AISI 304 grade, as taken from Zaera et al (2012Zaera et al ( , 2013. s Y a and s Y m were adopted as representative of the plastic flow stress in austenite and martensite, respectively .…”

“…2. Adiabatic loading process: both the stability analysis and the finite element modeling take into account the thermomechanical coupling in the phase transformation kinetics according to the experimental observations reported elsewhere (Olson and Cohen, 1975;Tomita and Iwamoto, 1995;Rodríguez-Martínez et al, 2011;Zaera et al, 2012Zaera et al, , 2013. Thus, this section examines the effect of temperature on the transformation rate which, in turn, affects the transformation hardening and consequently the processes of necking inception and energy absorption.…”

Approaching steady cavitation: The time scale in hypervelocity cavity expansion in work hardening and transformation hardening solids

“…The strain as well as the strain rate of the austenite are quite close to the homogenized ones and much larger than those corresponding to the martensite [27]. Therefore, based on Zaera et al [21], the plastic deformation in the austenite ε and the plastic deformation of the steel ε p are considered equivalent in the current approach, and Eq.…”