Stress corrosion cracking of carbon steels and low alloy steels

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.

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Mechanism of Stress Corrosion Cracking of Low Alloy Steel in Water

CORROSION ◽

10.5006/1.3577280 ◽

1981 ◽

Vol 37 (6) ◽

pp. 320-327 ◽

Cited By ~ 22

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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Transgranular Stress Corrosion Cracking of Mild Steels and Low Alloy Steels in the H2O-CO-CO2 System

CORROSION ◽

10.5006/0010-9312-24.12.427 ◽

1968 ◽

Vol 24 (12) ◽

pp. 427-429 ◽

Cited By ~ 19

Author(s):

M. KOWAKA ◽

S. NAGATA

Keyword(s):

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Corrosion Cracking ◽

Low Alloy Steels ◽

Alloy Steels

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Stress Corrosion Cracking of Mild and Low Alloy Steels in CO-CO2-H2O Environments

CORROSION ◽

10.5006/0010-9312-32.10.395 ◽

1976 ◽

Vol 32 (10) ◽

pp. 395-401 ◽

Cited By ~ 15

Author(s):

MASAMICHI KOWAKA ◽

SABURO NAGATA

Keyword(s):

Mild Steel ◽

Stress Corrosion ◽

Stress Corrosion Cracking ◽

Laboratory Tests ◽

Corrosion Cracking ◽

Low Alloy Steels ◽

Wide Range ◽

Alloy Steels ◽

Increasing Temperature ◽

Co2 Environment

Abstract This paper is related to the new stress corrosion cracking phenomenon of mild and low alloy steels in a CO/CO2 environment. The incidents of cracking are described and these were reproduced by laboratory tests. The results obtained are as follows: (1) No stress corrosion cracking of mild steel was found to occur in water containing just CO or CO2. (2) The transgranular stress corrosion cracking occurred only in CO/CO2 environment with water. (3) Stress corrosion cracking occurred in a wide range of CO/CO2 ratios in water. (4) The susceptibility to stress corrosion cracking of mild steel decreases with increasing temperature. (5) No stress corrosion cracking was found to occur on 18Cr-10Ni stainless steel. (6) From the study of electrochemical measurements, the mechanism has been proposed that this form of cracking is stress corrosion cracking rather than hydrogen embrittlement. (7) Prevention of stress corrosion cracking in these environments is discussed.

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