Kishore, Kaushal and Kumar, R Gaurav and Chandan, A K (2021) Critical assessment of the strain-rate dependent work hardening behaviour of AISI 304 stainless steel. Materials Science and Engineering A, 803 . p. 140675.
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In the present work, the effect of strain rate on the micro-mechanism of plastic deformation and ensuing work hardening behaviour of AISI 304 stainless steel has been critically investigated. The defining role of the early stage of deformation (<10% strain) on subsequent work hardening behaviour which is often ignored has been discussed in detail. It was found that there is a cross-over in the work hardening plot of slow strain rate (SSR) and high strain rate (HSR) specimen at around 5% strain and therefore to understand the sequential hardening behaviour, interrupted tensile tested specimens at 3, 10, 30% strain and up to the point of fracture were examined with respect to substructure evolution using transmission electron microscope and electron back-scattered diffraction. While the propensity of gamma ->alpha' in 3% strained specimen at HSR was higher contributing to lower transition strain from stage 1 to 2 of work hardening compared to SSR, the extent of work hardening was higher in the latter case during the stage 2 due to a combined effect of extensive twinning and deformation induced martensite formation, which was limited in HSR due to occurrence of cross-slip. These differences in the work hardening mechanisms were manifested as an improvement in UTS/YS ratio from 2.66 to 2.99 in HSR and SSR specimens, respectively. Furthermore, changes in the mechanism of plastic deformation was also reflected as similar to 4 fold increase in dislocation density for SSR specimen compared to HSR specimen at any given strain level and nearly 27% increase in hardness at the point of fracture. A significant improvement in UTS/YS ratio and ductility for SSR specimen left its signature on the fracture surface in form of three-fold increase in the number density of finer dimples compared to HSR specimen.
|Official URL/DOI:||DOI: 10.1016/j.msea.2020.140675|
|Uncontrolled Keywords:||Austenitic stainless steel; Deformation induced martensite; Work hardening; Dislocation density; Quantitative fractography|
|Divisions:||Material Science and Technology|
|Deposited By:||Dr. A K Sahu|
|Deposited On:||02 Jul 2021 13:06|
|Last Modified:||02 Jul 2021 13:06|
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