Size Effect on Tensile Properties of Cold-Rolled ASS-304 Sheets at Various Service Temperatures

Abstract

To investigate the relationship between service temperature ranging from –40~250℃, and size effect on tensile properties of thin ASS-304 sheets with nine different thicknesses (40~500 μm), uniaxial tensile tests were performed on thin ASS-304 sheets of the same average grain size in the present study. Within the thickness range of 40 to 300 μm, corresponding to η = t/d values from 1.1 to 8.1. The ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) of ASS-304 exhibits a dimensional effect of “the thinner, the stronger”. For example, as the η increases from 1.1 to 8.1, the UTS rapidly decreased from 1798.8 to 839.0 MPa at 20℃, from 1703.1 to 526.9 MPa at 150℃, and from 1661.2 to 478.9 MPa at 250℃, attenuation of 53.36, 69.06, and 71.17%, respectively. Meanwhile, the YS at 20℃ are separately 1768.9 to 418.7 MPa with 1695.2 to 343.3 MPa at 150℃ as well as 1645.7 to 330.1 MPa at 250°C, decrease the proportion of 76.33%, 79.75% and 79.94% respectively. Notably, the UTS, YS, and EL at 150 and 250℃ are lower than those at 20℃. The true stress value of ASS-304 was enhanced at –20 and –40℃, and the true strain increases first and then weakens as the thickness increases, the reason is the transformation- induced-plasticity (TRIP) effect of ASS-304 in stretching. The asymptotic function describes the relationship between strength and the values of η, while the Chapman function represents the relationship between elongation and the η. A linear variation exists between service temperature and tensile properties. And relevant empirical equations including T-η- and T-η-tensile properties were established, which can predict the UTS, YS, and EL of thin ASS-304 sheets under different service temperatures.