Influence of Impurities on Intergranular Corrosion of Extra High Purity Austenitic Stainless Steels

Author(s):  
Ikuo Ioka ◽  
Jun Suzuki ◽  
Takafumi Motoka ◽  
Kiyoshi Kiuchi ◽  
Junpei Nakayama

An intergranular corrosion is observed in austenitic stainless steels exposed to high temperature, concentrated nitric acid (HNO3) solution with highly oxidizing ions. It is an important degradation mechanism of austenitic stainless steels for use in a nuclear fuel reprocessing plant. The intergranular corrosion is caused by the segregation of impurities to grain boundaries and the resultant formation of active sites. Extra High Purity (EHP™) austenitic stainless steel was developed with conducting the new multiple refined melting in order to suppress the total harmful impurities less than 100ppm. The intergranular corrosion behavior of EHP alloys with various impurities was examined in boiling HNO3 solution with highly oxidizing ions to find a correlation between the intergranular corrosion and the impurities of EHP alloys. A good correlation was confirmed between the degree of intergranular corrosion and the corrosion rate. The relationships between the corrosion rate and the impurities content of EHP alloys was determined using a multiple regression analysis. The influence on corrosion rate became small in order of B, P, Si, C, S and Mn. It was important to control B in intergranular corrosion behavior of EHP alloys.

CORROSION ◽  
1968 ◽  
Vol 24 (12) ◽  
pp. 393-402 ◽  
Author(s):  
B. E. WILDE ◽  
J. S. ARMIJO

Abstract The influence of silicon and manganese on the electrochemical and corrosion behavior of a high purity austenitic 14Cr/14Ni-balance Fe alloy has been studied. Over the composition range 50–41, 500 ppm Si, no effect was observed on the kinetics of the anodic or cathodic partial processes. Addition of manganese over the range 5–26,300 ppm accelerates the anodic dissolution kinetics in the active range of potentials and also the steady-state corrosion rate in 1N̄ H2SO4 due to its influence on the kinetics of the cathodic partial process. The nature of this effect is analyzed according to electrode kinetic concepts from which it is shown that manganese changes the value of the electrode process transmission coefficient. Alloys containing manganese and silicon over large concentration ranges are extremely resistant to stress corrosion cracking in boiling 42 w/o MgCl2.


2010 ◽  
Vol 4 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Ikuo IOKA ◽  
Jun SUZUKI ◽  
Takafumi MOTOKA ◽  
Kiyoshi KIUCHI ◽  
Junpei NAKAYAMA

2016 ◽  
Vol 25 (9) ◽  
pp. 3615-3626 ◽  
Author(s):  
Ankur V. Bansod ◽  
Awanikumar P. Patil ◽  
Abhijeet P. Moon ◽  
Nilay N. Khobragade

1986 ◽  
Vol 8 ◽  
pp. 593-604 ◽  
Author(s):  
Gianni Rondelli ◽  
B. Mazza ◽  
Tommaso Pastore ◽  
Bruno Vicentini

1999 ◽  
Vol 48 (3) ◽  
pp. 169-175 ◽  
Author(s):  
Alberto A. Ono ◽  
Tadashi Shinohara ◽  
Shigeo Tsujikawa

Alloy Digest ◽  
2021 ◽  
Vol 70 (9) ◽  

Abstract CarTech 347 is a niobium+tantalum stabilized austenitic stainless steel. Like Type 321 austenitic stainless steel, it has superior intergranular corrosion resistance as compared to typical 18-8 austenitic stainless steels. Since niobium and tantalum have stronger affinity for carbon than chromium, carbides of those elements tend to precipitate randomly within the grains instead of forming continuous patterns at the grain boundaries. CarTech 347 should be considered for applications requiring intermittent heating between 425 and 900 °C (800 and 1650 °F). This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1339. Producer or source: Carpenter Technology Corporation.


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