Pitting and Intergranular Corrosion Resistance of AISI Type 301LN Stainless Steels

Abstract

The pitting and intergranular corrosion (IGC) resistance of AISI type 301LN stainless steels were evaluated using ASTM methods, anodic polarization, and electrochemical impedance techniques. The IGC results indicated that the microstructure of the samples after sensitization heat treatment at 675°C for 1 h shows step or dual structure for both imported and indigenous materials indicating insignificant Cr 23 C 6 precipitation. The results of immersion tests in boiling 6% copper sulfate + 16% sulfuric acid + copper solution for 24 h followed by the bend test (ASTM A262 Practice-E method) indicated no crack formation in any of the tested specimens. Pitting corrosion resistance carried out in 6% FeCl 3 solution at different temperatures of 22 ± 2 and 50 ± 2°C (ASTM G 48) up to the period of 72 h revealed pitting corrosion attack in all the investigated alloys. The potentiodynamic anodic polarization results in 0.5 M NaCl revealed variation in passive current density and pitting potential depending on the alloy chemistry and metallurgical condition. The passive film properties studied by electrochemical impedance spectroscopy (EIS) correlated well with the polarization results. The x-ray diffraction (XRD) results revealed the presence of austenite (c) and martensite (a¢) phases depending on the material condition. The suitability of three indigenously developed AISI type 301LN stainless steels were compared with imported type 301LN stainless steel and the results are highlighted in this article.

Corrosion Behaviour Corrosion Behaviour of Cold-Deformed Austenitic Alloys

“…However, this is not adequate to resist corrosion in acids such as HCl or H 2 SO 4 (Azambuja et al, 2003;Kurc et al, 2010). In environments containing chloride the austenitic steels are susceptible to localized corrosive attacks, such as pitting corrosion, intergranular corrosion and stress corrosion cracking (SCC) (Osawa & Hasegawa, 1981;Ningshen et al, 2010).…”

Optical spectroscopic and electrochemical characterization of oxide films on a ferritic stainless steel

“…A high R pl implies the excellent capability of prevention against corrosion, while a lower value indicates the interaction of sample and electrolyte on accelerating the corrosion of oxide films. [ 18,45 ] A substrate with a passive film as a protective barrier shows high polarization resistance. The dense passive film reduces the electrochemical reaction rates on the surface of stainless steel whereas oxide films impair the corrosion resistance.…”

Effect of ferrite on pitting corrosion of Fe20Cr9Ni cast austenite stainless steel for nuclear power plant pipe

“…27,29 Pitting resistance of specimens with different ferrite contents in the passive region of metal surface. 5 The lowest I p value occurred in the specimen A 5 with the lowest ferrite content, which results in a decrease in anodic dissolution. As observed in Fig.…”

“…The impedance expression of CPE is given by Z CPE = 1/[T( j ω) n ], where ω is the angular frequency, T (CPE-T) and n (CPE- n ) are frequency-independent fit parameters, j = (−1) 1/2 , and ω = 2π f , where f is the frequency (Hz). 5 The characteristic parameter values of these elements were then obtained directly by fitting the experimental curves using Zview Version 3.1 software.…”

“…Austenite stainless steels (ASSs) have been widely used in various engineering applications such as oil, chemical, petrochemical, marine and nuclear power industries owing to a good combination of high formability, strength, weldability and corrosion resistance. [1][2][3][4][5] However, they are susceptible to pitting corrosion in some aggressive environments, which results in catastrophic failure. 6,7 As reported in the literature, 1,[8][9][10][11] the microstructural features of stainless steels such as manganese sulphide inclusions, dferrite, s phase, a9 phase, ratio of a/c and sensitised grain boundaries play an important role in determining the pitting corrosion resistance of ASSs.…”