Hybrid effect of stress state and strain rate on the deformation and ductile fracture behaviour of TRIP800 steel sheet

摘要

The plastic deformation and ductile fracture (DF) bebaviour of a Transformation Induced Plasticity (TRIP) steel TRIP800 was investigated under different stress states and strain rates. Five specimens with different geometries were employed to obtain different stress states and deformation mechanisms. The results showed that both the stress state and strain rate have a significant effect on the mechanical properties and fracture mechanism of this alloy. It was found that the TRIP800 exhibits almost no strain-rate sensitivity below similar to 0.15 plastic strain for the medium strain rates from 1 s(-1) to 100 s(-1). Furthermore, scanning electron microscopy (SEM) fractography studies showed that when the specimen failed under pure shear state it exhibited a shear fracture mode, while samples deformed under the uniaxial tensile and plane strain states exhibited a dominant dimple fracture mode. With an increase in the loading strain rate, the dimple fracture was restricted under lower stress triaxiality and enhanced at higher stress triaxiality, whereas the shear fracture was enhanced at a lower Lode angle.

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