CHINESE JOURNAL OF MECHANICAL ENGINEERING Vol. 30,aNo. 1,a2017 ·200· DOI: 10.3901/CJME.2016.0420.056, available online at www.springerlink.com; www.cjmenet.com Effects of Temperature and Pressure on Stress Corrosion Cracking Behavior of 310S Stainless Steel in Chloride Solution ZHONG Yunpan 1 , ZHOU Cheng 2 , CHEN Songying 1, * , and WANG Ruiyan 1 1 Key Laboratory of High-efficiency and Clean Mechanical Manufacture, Shandong University, Jinan 250061, China 2 Qingdao Boiler and Pressure Vessel Supervisory Institute, Qingdao 266071, China Received October 21, 2015; revised March 11, 2016; accepted April 20, 2016 Abstract: 310S is an austenitic stainless steel for high temperature applications, having strong resistance of oxidation, hydrogen embrittlement and corrosion. Stress corrosion cracking(SCC) is the main corrosion failure mode for 310S stainless steel. Past researched about SCC of 310S primarily focus on the corrosion mechanism and influence of temperature and corrosive media, but few studies concern the combined influence of temperature, pressure and chloride. For a better understanding of temperature and pressure’s effects on SCC of 310S stainless steel, prepared samples are investigated via slow strain rate tensile test(SSRT) in different temperature and pressure in NACE A solution. The result shows that the SCC sensibility indexes of 310S stainless steel increase with the rise of temperature and reach maximum at 10MPa and 160℃, increasing by 22.3% compared with that at 10 MPa and 80 ℃. Instead, the sensibility decreases with the pressure up. Besides, the fractures begin to transform from the ductile fracture to the brittle fracture with the increase of temperature. 310S stainless steel has an obvious tendency of stress corrosion at 10MPa and 160℃ and the fracture surface exists cleavage steps, river patterns and some local secondary cracks, having obvious brittle fracture characteristics. The SCC cracks initiate from inclusions and tiny pits in the matrix and propagate into the matrix along the cross section gradually until rupture. In particular, the oxygen and chloride play an important role on the SCC of 310S stainless steel in NACE A solution. The chloride damages passivating film, causing pitting corrosion, concentrating in the cracks and accelerated SSC ultimately. The research reveals the combined influence of temperature, pressure and chloride on the SCC of 310S, which can be a guide to the application of 310S stainless steel in super-heater tube. Keywords: 310S stainless steel, SSRT, stress corrosion, chloride, temperature 1 Introduction Austenitic stainless steels, which possess high corrosion resistance and good mechanical properties, are widely used in piping systems in the petrochemical industry and nuclear power plants [1] . 310S is an austenitic stainless steel for high temperature applications(about 800℃), especially in oil, gas and petrochemical industries containing hot concentrated acids. Due to the high levels of nickel and chromium in the chemical compositions, 310S is extremely resistant to oxidation, hydrogen embrittlement(HE) and corrosion [2–4] . SCC is a common corrosion mechanism for austenitic stainless steel, which also is the main corrosion failure mode for 310S stainless steel. Even if damage of SCC has been observed over more than a century, SCC mechanisms are still under debate. The two most classical categories of mechanisms are anodic dissolution and * Corresponding author. E-mail: [email protected] Supported by National Basic Research Program of China(973 Program, Grant No. 2011CB013401), and General Administration of Quality Supervision, Inspection and Quarantine of China(Grant No.2011QK235) © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2017 hydrogen induced cracking [5] . Due to the deficiencies and limitations of above mechanisms, several new mechanisms have been proposed during the past few decades, such as slip dissolution model, tunnel corrosion model and hydrogen induced plasticity theory [6–7] . Many researches on the corrosion of 310S stainless steel have been done so far. BEHNAMIAN, et al, researched the stress corrosion cracking behavior of austenitic alloys in pure supercritical water. The result showed that crack initiations were readily observed in all samples, signifying susceptibility to stress corrosion cracking. The microcracks in 316L stainless steel and Inconel 625 were almost intergranular, whereas transgranular microcrack initiation was observed in 310S stainless steel [8] . The transgranular cracking mode was also found in all sensitized type 310 specimens in boiling saturated magnesium chloride(MgCl 2 ) in ALYOUSIF and NISHIMURA’s research [9] . WANG Wenwen’s works shows the crack initiates in the corrosion product film(CPF) of 310S specimen and the existence of the CPF-induced stress yields first the specimen and facilitates SCC [10] . UCHIDA, et al, found the susceptibility to SCC of 310S stainless steel under constant load conditions increased in the order of [111], [101] and [001]
Effects of Temperature and Pressure on Stress Corrosion Cracking Behavior of 310S Stainless Steel in Chloride Solution
May 17, 2023
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