A Lower-Bound Temperature and Strain-Rate Dependent Strength Model for AISI 304 SS

Abstract

The use of a material in a design where failure carries environmental or health and safety risk requires computational design using a conservative strength model. The materials design engineer must determine and be able to justify a lower-bound stress-strain curve. This paper uses the AISI 304 / 304L system to demonstrate how such a model might be derived. It addresses the question of variability in materials properties. Also discussed is the contribution of strain-rate dependence that is relevant to applications involving impact or explosive loading conditions. Designers and those reviewing and approving designs are more comfortable with the use of temperature dependent than strain-rate dependent material properties. Ignoring strain-rate dependence can lead to overly conservative designs, even when the objective is a conservative design. The Mechanical Threshold Stress model is used to demonstrate, in the 304 / 304L system, a lower-bound temperature and strain-rate dependent constitutive model. This model implements a state-variable approach and easily accounts for temperature and strain-rate dependent material properties as well as strain hardening. A wealth of literature data is used to benchmark and validate the model. Comparison of model predictions with applicable ASME and ASTM code standards is described.

Application to Austenitic Stainless Steels

“…The departure between the low-temperature (and high strain rate) and high-temperature (and low strain rate) behaviors is evident in Figure 11.3. This, in fact, is a consistent trend observed in other AISI 304, 304L, 316, and 316L temperaturedependent yield stress measurements [19,20].…”

Strain Effect On Microstructural Properties Of SUS 304L Joint By PAW+GTAW

“…Therefore, the thickness of pressure vessel is large as some heavy equipment resulting in serious waste of materials owing to its low yield strength and low bending strength ratio, which leads to high cost of manufacturing and transportation. The yield strength of 304L steel can be effectively improved by pre-strain strengthening treatment to make it partially plastic deformed on the premise that the original mechanical properties of 304L steel are not greatly affected [1][2][3]. The thickness of vessels designed by new yield strength after strain strengthening can be reduced by 20%-30%, which is favorable to save materials, reduce costs and energy consumption in transportation [4].…”

Strain effect on microstructural properties of SUS 304L joint by PAW+GTAW

“…Therefore, the thickness of pressure vessel is designed to be large in some heavy equipment owing to its low ratio of yield strength to tensile strength, which leads to high cost of manufacturing, transportation, and waste of materials. The yield strength of JIS SUS 304L steel can be significantly improved by prestrain treatment to make it partially plastic deformed on the premise that the original mechanical properties of 304L steel are not greatly affected [1][2][3]. The thickness of pressure vessels designed by new yield strength after pre-strain can be reduced by 20-30 %, which is favorable to save materials and reduce costs and energy consumption in transportation [4].…”