LI Da-zhao
,
et al
钢铁研究学报(英文版)
The mechanical properties of the TWIP steel subjected to impact loading at various strain rates were analyzed by the Split Pressure Hopkinson Bar. Meanwhile the microstructure of the TWIP steel fore-and-after the dynamic deformation were characterized and analyzed by optical microscopy (OM), X-ray diffraction (XRD), and transmission electron microscope (TEM). The result shows that when the TWIP steel was deformed under dynamic station, the stress, microshardness and work hardening rate increase with the increment of strain and strain rate; there exist stress fluctuation and decline of work hardening rate for adiabatic temperature rising softening. There exist many pin-like deformation twins in the microstructure of the TWIP steel subjected to impact loading, the grain size after deformation is bigger than that before; the interaction of twins with dislocation and twins with twins, especial emergence of high order deformation twins are the main strengthening mechanisms of the TWIP steel. The nucleation mechanism of deformation twins will be “rebound mechanism”; the incomplete deformation twins can be observed when the strain rate is low; when strain rate raises, deformation twins unite together; furthermore, deformation twins become denser because the nucleation rating enhancing with strain rate increasing.
关键词:
TWIP;Split Pressure Hopkinson Bar;Deformation twins;Strain rate;Work hardening
ZTANG heng-you
,
DING Hua
,
et al
钢铁研究学报(英文版)
After 2% pre-deformation, the baking treatment with different schedule was carried out in low silicon TRIP steel sheet with niobium. The effects of baking temperature and time on microstructures and mechanical properties were investigated. The results show that, with increasing of baking temperature and time, the volume fraction of retained austenite decreases, and tempered martensite increases; As baking temperature ranging from 80 to 170℃, the bake-hardening(BH) value increases obviously, while from 170℃ to 230℃, the variation of BH value is very slight; As baking time ranging from 2 to 20 min, the BH value increases significantly, while the BH value decreases when it exceeds 20 min. So that when the baking temperature is 170℃ and the baking time is 20 min, the low silicon TRIP steel sheet exhibits good bake-hardening behavior, the highest BH value being above 70MPa.
关键词:
TRIP steel sheet;baking process;microstructures;mechanical properties;bake-hardening
