Stress Corrosion Cracking Susceptibility of Low Alloy Steels Used for Reactor Pressure Vessel in High Temperature Oxygenated Water

1985 ◽  
Vol 107 (4) ◽  
pp. 430-435 ◽  
Author(s):  
J. Kuniya ◽  
I. Masaoka ◽  
R. Sasaki ◽  
H. Itoh ◽  
T. Okazaki
Keyword(s):  
Dissolved Oxygen ◽  
Strain Rate ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Pressure Vessel ◽  
Corrosion Cracking ◽  
Reactor Pressure Vessel ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Reactor Pressure

Studies have been done on stress corrosion cracking (SCC) susceptibility of low alloy steels in water containing dissolved oxygen. The fundamental factors which affect the SCC susceptibility were clarified, and the integrity of the reactor pressure vessel (RPV), in which these steels are used, was assessed from the standpoint of SCC initiation. The effects of applied stress, strain rate, dissolved oxygen concentration, and test temperatures, on the SCC susceptibility was examined utilizing uniaxial constant load tensile tests (UCL), and slow strain rate tests (SSRT).

Intergranular microchemistry and stress corrosion cracking

1981 ◽  
Vol 377 (1771) ◽  
pp. 477-501 ◽  
Keyword(s):  
Grain Boundary ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Nitrate Solution ◽  
Corrosion Cracking ◽  
Low Alloy Steels ◽  
Intergranular Stress Corrosion ◽  
Oxidation Potentials ◽  
Alloy Steels ◽  
Impurity Elements

An important contributory role of grain boundary segregation of residual impurities in the intergranular stress-corrosion cracking of carbon and low alloy steels is proposed. Experimental results are presented of the stress corrosion susceptibility of mild steel in nitrate solution, and in relation to varying grain boundary composition as monitored by Auger electron spectroscopy. The harmfulness of a particular impurity element depends on three factors: its bulk level; its segregation thermodynamics and kinetics resulting in an equilibrium enrichment at the grain boundaries; and its ability to promote electrochemical dissolution of the grain boundary. A hierarchy of impurity elements that exacerbate stress corrosion cracking is presented and correlated with equilibrium oxidation potentials. The results and simple model allow the prediction of the relative harmfulness of impurity elements with respect to intergranular stress corrosion in commercial carbon and low alloy steels from a knowledge of the bulk concentration only. This enables significant improvements in performance to be designed in the alloy by respecifying lower levels of only the one or two highly detrimental impurities.

Mechanism of Stress Corrosion Cracking of Low Alloy Steel in Water

CORROSION ◽  
1981 ◽  
Vol 37 (6) ◽  
pp. 320-327 ◽  
Author(s):  
Wu-Yang Chu ◽  
Tian-Hua Liu ◽  
Chi-Mei Hsiao ◽  
Shi-Qun Li
Keyword(s):  
Plastic Deformation ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Cathodic Polarization ◽  
Optical Microscope ◽  
Corrosion Cracking ◽  
Low Alloy Steels ◽  
Wide Range ◽  
Alloy Steels ◽  
Loaded Crack

Abstract For four low alloy steels with a wide range of tensile strengths, the dynamical processes of the nucleation and propagation of stress corrosion cracking (SCC) in water with various polarization conditions and in a inhibitor solution were traced with an optical microscope. The results show that if the tensile strength of the steel is higher than a critical value, which is different in the different polarization conditions, and KI>KISCC, the plastic zone in front of a loaded crack tip is enlarged with time, i.e., the delayed plastic deformation occurs in all the environments used. The nucleation and propagation of SCC will follow when this delayed plastic deformation develops to a critical condition. Neither anodic and cathodic polarization nor the inhibitor can change the feature of the delayed plasticity and the nucleation and propagation of SCC in water. In all the environments used, the KISCC is increased and da/dt is decreased with decreasing strength of the steel. Anodic polarization and the addition of the inhibitor make KISCC increase and da/dt decrease. But cathodic polarization is just opposite.

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