Grain boundary engineering for improving stress corrosion cracking of 304 stainless steel

Abstract

Grain boundary engineering (GBE) via low strain tension and annealing was used to enhance the resistance to stress corrosion cracking of a 304 stainless steel. Electron backscattered diffraction (EBSD) analysis exhibited that the GBE steel had a higher fraction of low-∑ coincidence site lattice (CSL) boundaries, larger grain-clusters, longer twin boundary chains, and fewer paths of connected non-twin boundaries with a more zigzag shape. Slow strain rate tests in high-temperature water showed that the GBE steel performed better plasticity, higher tensile strength, and similar yield strength compared to conventional steel. The low fraction of random boundaries in GBE steel resulted in a lower frequency of intergranular crack initiation, and the zigzag paths of non-twin boundaries made the intergranular crack propagation more difficult.

Corrosion behaviour of nanocrystallines 304 stainless steel in simulated secondary side environment

“…Stainless steel (SS) with excellent corrosion resistance is usually used as pressurised water reactor (PWR) material, such as steam generator heat transfer tubes, heat transfer tube supports, cooling water piping, etc. However, The corrosion behaviour of SS, such as stress corrosion cracking (SCC), still remains due to its long service in harsh PWR environment [1,2]. In order to prolong the service life of components and improve the safety of nuclear power plant, it is necessary to further improve the corrosion resistance of SS.…”

“…The hydration environment on the primary side is mainly high temperature and high pressure water containing boron and lithium. There are many researches on the corrosion performance of 304 SS in the primary side of PWR [1,15,16]. Lv [17] et al reported the corrosion behaviour of nano/ultrafine 304 stainless steel in pH 9.2 borate buffer solution, suggesting that the grain refinement facilitate more Cr 2 O 3 on the surface and promote the formation of thicker passivation films to improve its corrosion resistance.…”

Relationship between Microstructure and Corrodibility of Local Dry Underwater Laser Welded 304 Stainless Steel

“…Cr-depleted regions formed in austenitic stainless steel, such as 304 SS, are known to be vulnerable to corrosion [35,36]. From the EPMA analysis illustrated in Figure 9a-c, no significant areas of localized Cr- In general, it is known that HAGBs are vulnerable to corrosion, and LAGBs are highly resistant to corrosion [21][22][23][24]. GBs with low-∑ CSLs are also resistant to corrosion [22,23,33,34].…”

“…Classification of GBs into the following three types is possible: low-angle grain boundaries (LAGBs), random high-angle grain boundaries (HAGBs), and coincidence site lattice (CSL) boundaries (3 ≤ ∑ ≤ 29) [21][22][23][24]. It is known that HAGBs are vulnerable to corrosion, while LAGBs and CSL boundaries are resistant to corrosion [17,[21][22][23][24]. Electron probe microanalysis (EPMA, JXA-8530F) was also performed to investigate the elemental distribution in the welded material.…”