Steel In Sodium Chloride Solution Research Articles

CRACK NUCLEATION AND PROPAGATION IN BLADE STEEL MATERIAL

AbstractStress corrosion cracking and corrosion fatigue of 12 Cr steel in sodium chloride solution has been investigated. Tests have been performed in air at room temperature and in aqueous solution with 22% NaCl at 80°C. The influence of corrosion pits on crack nucleation has been investigated. On fracture surfaces tested in environment (22% NaCl solution), crack initiation was observed in correspondence with corrosion pits; in this case fatigue life can be described using a fracture mechanics approach. The ΔK value for crack nucleation from a pit in rotating bending fatigue tests is very low in air (about 3 MPa√m). The results of slow strain rate tests on smooth specimens show that there is a threshold stress intensity, KISCC, of about 15 MPa√m and a plateau in stress corrosion crack growth rate of about 10‐5mm/s.

Corrosion mechanisms of an AISI type 316L sintered stainless steel in sodium chloride solution

AbstractThe electrochemical behaviour of a sintered stainless steel and of a wrought AISI type stainless steel of the same composition were compared. The electrochemical measurements used were the evolution of the corrosion potential vs time, the anodic and cathodic polarizations and the current‐time transients. Comparisons were also performed for the sintered alloy before and after stabilization of the corrosion potential. The low corrosion resistance of the sintered stainless steel is due to the formation of a galvanic couple between the free surface and the inside of the interconnected pores. Hence the free surface is cathodically protected by the pores, but reciprocally the corrosion increases inside the pores where the reactive area is very large.

Mechanism of Corrosion Inhibition of N-80 Steel in Sodium Chloride Solution Using Corrosion Inhibitors

Mechanism of Corrosion Inhibition of N-80 Steel in Sodium Chloride Solution Using Corrosion Inhibitors

A probabilistic assessment for the stress corrosion cracking lifetime of sensitized 304 stainless steel in sodium chloride solutions.

Since stress corrosion crack initiation/propagation process is essentially a stochastic one, a series of uniaxial constant load tests have been conducted on sensitized 304 stainless steel specimens in neutral chloride solutions to examine the effects of stress, temperature, crevice and chloride ion concentration on probability distribution of intergranular stress corrosion cracking lifetime. By examining the effects of various acceleration factors, the lifetime distribution can be satisfactorily presented by the exponential probability distribution model as that of sensitized stainless steels in high-temperature and high-purity water environment systems. The tendency of both the location parameter, i.e., lower limit of lifetime distribution, and the scale parameter, i.e., standard deviation of lifetime distribution, to increase with decreasing stress, temperature and chloride ion concentration, also the ratio of those two parameters is constant.

Corrosion Behaviour of Nitrided Steels in Sodium Chloride Solutions

Corrosion Behaviour of Nitrided Steels in Sodium Chloride Solutions

The study of the stability of passive films using potentiostatic-galvanostatic transient technique

An on-line measurement system of potentionstatic-galvanostatic (P-G) transient response of the passive metals was established. A mathematical model for P-G response curves in the case of the pitting was set up. Using the Monte Carlo method the electrochemical parameters which characterized the stability of passive films were calculated from the sampling data of the response curves. The results for some steels in sodium chloride solution measured by this technique were presented and the features of the breakdown of passive films for different steels were discussed.

Discussion on the “Influence of Strain on the Environmental Hydrogen-Assisted Cracking of a High-Strength Steel in Sodium Chloride Solution”

Abstract The following article is a discussion of the paper entitled “Influence of Strain on the Environmental Hydrogen-Assisted Cracking of a High-Strength Steel in Sodium Chloride Solution,” by J...

The Influence of Strain on Hydrogen Entry and Transport in a High Strength Steel in Sodium Chloride Solution

The influences of mechanical strain on hydrogen entry and transport are reported for a high strength steel alloy (AISI 4340) under cathodic polarization in aqueous sodium chloride solution. The overall rate of hydrogen permeation and the quantity of hydrogen absorbed are shown to be particularly low in alkaline chloride at low cathodic current densities if the charging surface has been contaminated by slight corrosion. Evidence is presented that illustrates the role of mechanical strain in promoting enhanced hydrogen absorption as a result of film rupture. In addition to the conventional Devanathan‐Stachurski method, results from plastic straining of a cylindrical annular Devanathan‐Stachurski sample confirm the film rupture concept. Film removal is shown to enhance the overall rate of hydrogen entry by increasing the hydrogen surface coverage and possibly the adsorption‐absorption rate constant on the bare surfaces formed. This increases the mobile hydrogen concentration in the metal lattice. The presence of the intact metastable film modifies the kinetics of the hydrogen evolution reaction, lowering the cathodic hydrogen overpotential at a given cathodic current density. This, consequently, is shown to lower hydrogen absorption for a given cathodic current density. The net effect of film rupture is to promote an increase in the hydrogen permeation rate independent of changes in the diffusion coefficient. Additional information indicates that long range enhanced diffusion of hydrogen by dislocation transport is not observed. Further evidence suggests that for sharp cracks, the rate of hydrogen accumulation at a position a distance from the crack tip where the crack initiates is an absorption controlled transport process. These findings provide additional insight on the rate limiting steps controlling the “time dependent” hydrogen assisted failure process of high strength steels in sodium chloride solution.

Influence of Strain on the Environmental Hydrogen-Assisted Cracking of a High-Strength Steel in Sodium Chloride Solution

Abstract Evidence is presented that will establish the role of mechanical strain in promoting surface absorption of hydrogen by rupturing surface films on AISI 4340 steel in alkaline 3.5% sodium ch...

塩水中での塗装亜鉛めつき鋼板の耐食性

塩水中での塗装亜鉛めつき鋼板の耐食性

Aluminium-Thiourea Mixtures as Corrosion Inhibitors for Mild Steel in 1·0% NaCl

The inhibitive properties of mixtures containing aluminium salts and thiourea (so called aluminium-thiourea inhibitors) have already been investigated in relation to their inhibitive properties towards mild steel corrosion in distilled water and in water of high specific salinity (1·0% Na2SO4. This paper reports laboratory test data obtained during further investigations of aluminium-thiourea inhibitors in another corrosive medium, 1·0% NaCl at 20°c and under stagnant conditions. It was found that the corrosion rate of mild steel in sodium chloride solutions can be decreased markedly (by ~ 80%) if aluminium ions are used in the form of a mixture of sulphates and oxychlorides and in conjunction with thiourea, cationic surfactants and reducing agents (SnCl2). Any change in the composition of the aluminium salts in the mixture, keeping a constant Al3+ concentration (for instance a substitution of sulphates/oxychlorides by sulphates/chlorides or chlorides/oxychlorides) reduces the inhibitive efficiency of the formulations tested. The author fails to find a satisfactory explanation of the very specific inhibitive behaviour of aluminium-thiourea mixtures in 1·0% NaCl.

Corrosion Fatigue Strength of S35C Carbon Steel in Sodium Chloride Solution with Various Concentration

Corrosion Fatigue Strength of S35C Carbon Steel in Sodium Chloride Solution with Various Concentration

Discussion:The Galvanic Corrosion of Steel in Sodium Chloride Solution

Abstract The following is a discussion of the article entitled “The Galvanic Corrosion of Steel in Sodium Chloride Solution” by B. Tsujino and S. Miyase, published in Corrosion, Vol. 38, p. 226 (1982) April.

オーステナイトステンレス鋼の低温塩化ナトリウム水溶液中における陽極的挙動

オーステナイトステンレス鋼の低温塩化ナトリウム水溶液中における陽極的挙動

The Galvanic Corrosion of Steel in Sodium Chloride Solution

Abstract This paper describes a study of the galvanic corrosion of steel coupled to noble metals in sodium chloride solutions. The corrosion behavior was measured by the amount of galvanic current with a zero impedance ammeter and by the weight loss. The galvanic current flowing from the steel is not related to the cathodic metal, but is proportional to the area ratio of the steel to the cathodic metal. The galvanic current density flowing in the cathodic metal is not related to the area ratio or to the nature of the cathodic metal, and approaches the limiting current density for oxygen reduction. Further, local action currents on the steel depend on the area ratio of the steel to the cathodic metal and they are not related to the concentration of sodium chloride in neutral solution.

Experimental Observations and Analysis of Hydrodynamic Effects on Growth of Small Pits

Abstract Potentiostated pitting experiments were conducted with zone refined iron and commercial Type 304 stainless steel in sodium chloride solutions. Growth of single small pits initiated at small holes in a lacquer surface layer was observed under a microscope at 60X under stagnant and controlled hydrodynamic flow conditions. Three modes limiting pit growth rate were determined; hemispherical diffusion, hydrodynamic boundary layer diffusion, and solution ohmic resistance. Experiments showed that for a given size pit, there is a threshold velocity below which hydrodynamic flow is not important and that there is a critical velocity above which current density is limited by ohmic drop in solution. Stainless steel repassivates at the ohmic limited current density and pitting stops.

ステンレス鋼銀ろう付部の腐食機構について

The corrosion behaviour of silver brazed SUS 304 stainless steel in sodium chloride solutions with the additions of cupric chloride has been investigated using electrochemical and metallographic techniques. The interfacial corrosion mechanism was discussed in relation to the polarization behaviour of SUS 304. The cause of the interfacial corrosion of stainless steel was found to be attributable to the removal of corrosion resistant passive oxide films on stainless steel during brazing by brazing flux, because the anodic reaction was enhanced by the flux treatment. The interfacial corrosion could be penetrated along the narrow and less corrosion resistant zone between filler and stainless steel.Preferentially dissolved zinc and copper from α-Cu phase precipitated as chlorides on the specimen surface. The added copper in corrosive solution enhanced the corrosion rate by accelarating the cathodic reaction of both stainless steel and filler alloy. The precipitation of the metallic copper produced by cathodic reduction was occurred on the cathodic site such as al-Ag phase of filler alloy and stainless steel surface. The pH change during the immersion test was thought to be caused by the precipitation of added copper and the dissolution of iron, zinc and other alloying elements.

Effect of Heat Treatment on Pitting Corrosion of austenitic Cr‐Ni‐Mo steels in sodium chloride solution

AbstractThe pitting corrosion resistance of Cr 17 Ni 12 Mo 2,5 type steel under potentiostatic polarization in a sodium chloride solution is adversely affected by previous annealing. Even though the reproducibility and accuracy of measurements are limited due to the statistical nature of pitting, the data obtained were systematically dependent on annealing temperature, time and surface roughness. The corrosion current, the number of pits or the mean area of pit opening and the corrosion rate within the pits were increased by previous annealing at 550 to 750 °C for 1–100 hrs. The highest corrosion rate estimated corresponded to heat treatments provoking severe sensitization to intergranular corrosion. The percentage area of corrosion pit openings and the estimated pit penetration rates were several times higher for as‐machined than for polished surfaces. It can be assumed that pitting corrosion is little affected by the carbon content and that molybdenum depletion of grain‐boundary zones is responsible for the reduced pitting resistance of annealed steels.

食塩水中のステンレス鋼の隙間腐食と応力腐食割れに及ぼすCl<sup>-</sup>濃度と温度の影響

食塩水中のステンレス鋼の隙間腐食と応力腐食割れに及ぼすCl<sup>-</sup>濃度と温度の影響

Corrosion cracking of quench-hardened steels in sodium chloride solution

Corrosion cracking of quench-hardened steels in sodium chloride solution