Analysis of Strain Hardening Processes of AISI 316 LN Austenitic Stainless Steel

The primary objective of this contribution is to numerically and graphically evaluate engineering stress-strain curves, transform them into true stress-strain curves, and de-scribe the key points of material processed by cold rolling with strains of ε_Roll = 0%, 10%, 30%, and 50%. The initial and final conditions for uniform plastic deformations have been described. The initial point of uniform deformation lies above the onset yield strength value (σ_T,S > R_P0,2). The necking point, as the final point of uniform deformation, was determined as the intersection point of the curves of the true stress-strain and strain hardening rate. The strain hardening coefficient and the recovery rate, as a function of cold rolling deformations, were derived. Convex polyhedra were derived which describe the dependencies of the development of maximal strain hardening rate values (θ_Max) and initial strain hardening rates (θ₀) as a function of cold rolling deformations and the diameter of grain. The decisive point at which the curves showed a local maximum was a cold rolling deformation ε_Roll = 30%. The saturation stress required to initiate dynamic recovery of the microstructure is significantly higher than the stress necessary for necking (σ_T,Sat > σ_T,Neck). The saturation strain required to initiate dynamic recovery of the microstructure is significantly higher than the strain needed for necking formation (ε_T,Sat > ε_T,Neck).