Integrated modeling of second phase precipitation in cold-worked 316 stainless steels under irradiation

Abstract

The current work combines the Cluster Dynamics (CD) technique and CALPHAD-based precipitation modeling to address the second phase precipitation in cold-worked (CW) 316 stainless steels (SS) under irradiation at 300-400 °C. CD provides the radiation enhanced diffusion and dislocation evolution as inputs for the precipitation model. The CALPHAD-based precipitation model treats the nucleation, growth and coarsening of precipitation processes based on classical nucleation theory and evolution equations, and simulates the composition, size and size distribution of precipitate phases. We benchmark the model against available experimental data at fast reactor conditions (9.4 × 10 -7 dpa/s and 390 °C) and then use the model to predict the phase instability of CW 316 SS under light water reactor (LWR) extended life conditions (7 × 10 -8 dpa/s and 275 °C). The model accurately predicts the γꞌ (Ni 3 Si) precipitation evolution under fast reactor conditions and that the formation of this phase is dominated by radiation enhanced segregation. The model also predicts a carbide volume fraction that agrees well with available experimental data from a PWR reactor but is much higher than the volume fraction observed in fast reactors. We propose that radiation enhanced dissolution and/or carbon depletion at sinks that occurs at high flux could be the main sources of this inconsistency. The integrated model predicts ~1.2% volume fraction for carbide and ~3.0% volume fraction for γꞌ for typical CW 316 SS (with 0.054 wt.% carbon) under LWR extended life conditions. This work provides valuable insights into the magnitudes and mechanisms of precipitation in irradiated CW 316 SS for nuclear applications.

Characterization of Passive Films Formed on As-received and Sensitized AISI 304 Stainless Steel

“…Q is the constant phase element (CPE) considering relaxation times due to heterogeneities at the electrode surface [30,31]. The impedance of CPE is given by (1)…”

“…Austenitic stainless steels are widely used in components designed for high temperature applications like nuclear power stations, superheaters, and thermal power plant [1]. However, some localized corrosion such as pitting corrosion [2,3], intergranular corrosion [4], stress corrosion crack (SCC) [5,6] were often observed especially in the temperature range of 450-900 °C.…”

Microstructure Investigations of Phase Transformation in Cold Working AISI 316L Austenitic Stainless Steel

“…Duplex stainless steels have high mechanical properties and high corrosion resistance. One of the techniques to develop of duplex stainless steels are cold-working method of austenitic steels [8][9][10][11]. In the family of austenitic steels, 316 stainless steel [10] and 316L stainless steel [11] have high performance for duplex stainless steels steels.…”

Influences of Shot Peening Parameters on Mechanical Properties and Fatigue Behavior of 316 L Steel: Experimental, Taguchi Method and Response Surface Methodology

“…316L stainless steel does not harden in reaction to heat treatments [10][11][12][13]. However, it can be hardened by cold working, post-processing, and grain refinement treatments which are aimed at obtaining desirable mechanical properties [14][15][16][17].…”