Tensile Flow Analysis of Austenitic Type 316LN Stainless Steel: Effect of Nitrogen Content

Abstract

The tensile flow analysis of austenitic type 316LN stainless steel with nitrogen level ranging from 0.07 to 0.22 wt.% is studied at the temperatures from 300 to 1123 K and at a strain rate of 3 × 10−3 s−1 using Ludwigson flow relationship. It has been observed that Ludwigson flow relationship provided an appropriate description for the σ-ep behavior and subsequent work/strain hardening response which displayed three independent temperature regions of ambient (300 K), intermediate (523-923 K) and elevated temperature (≥ 923 K). The anomalous response in terms of stress–strain data grouping together in a narrow band and appearance of peaks/plateau in Ludwigson parameters in the intermediate temperature region (523-923 K) is attributed to the manifestation of dynamic strain aging (DSA). The parameters such as strain hardening exponent (n1) and coefficient (K1), transition stress (σL) and transition strain (ɛL) increased with increasing the amount of nitrogen that in turn diminished the propensity to dynamic recovery. The applicability of Ludwigson equation permitted to predict the flow stress response and yield strength as well as ultimate tensile strength values with one-to-one correlation in comparison with the experimental data.