مقاله انگلیسی رایگان در مورد خوردگی و قابلیت خوردگی تنشی فولاد ضد زنگ 316L – الزویر 2017

Abstract

This study investigated the corrosion and stress corrosion cracking susceptibility of 316L stainless steel exposed to 550 °C and 600 °C supercritical water. XRD, SEM, EDS and EBSD analyses have been carried out to characterize the microstructure of the tested specimens. Results indicate that increasing the test temperature reduced the corrosion and SCC resistance of 316L SS. The oxide scale of corroded specimen shows a duplex structure, and the fracture analysis indicates that the formation of Fe3O4 ‘channels’ in the Fe-Cr spinel layer contributes to the intergranular and transgranular SCC of the materials in 550 °C and 600 °C SCW.

Introduction

Generation IV reactors are attractive due to their high efficiency and safety [1,2]. The supercritical water cooled reactor (SCWR) is one of the most promising of the six innovative Generation IV reactor concepts because it offers advantages, such as simplification of components and higher efficiency [3,4]. By operating above the thermodynamic critical point of water (374 °C, 22.1 MPa), a single phase coolant is used in SCWR and many components, such as steam generators, steam separators, dryers, recirculation and jet pumps are not necessary [5,6]. Thus, the design of the reactor is greatly simplified.

In SCWR, the fuel cladding experiences the most severe conditions among the in-core structural components. During normal operation, the temperature on the fuel cladding can be 600 °C, and it can be even higher during transients. The higher the operating temperature, the higher the possibility that the fuel cladding material will fail due to creep [7], corrosion [6,8] or stress corrosion cracking (SCC) [6], which can result in leakage of fission products and pose great challenges to the reactor safety.

Stainless steels (SS) [8,9], nickel based alloys [10,11] and oxide dispersion strengthened steels (ODS) [12,13] have been proposed as candidate materials for fuel cladding and other core components in SCWRs, and extensive research has been conducted to examine the corrosion and SCC performance of those materials [14–17]. Among the candidate materials, austenitic stainless steels (SSs) are the least expensive, and some research [6] indicates that their corrosion resistance are better than nickel-based alloys. However, other research [18,19] reported that the corrosion rate of 316L SS was much higher than nickel-based alloys.