Stainless Steel In Water Research Articles

Benzotriazole as corrosion inhibitor for type 304 stainless steel in water–ethanol media containing 2M H2SO4

Benzotriazole as corrosion inhibitor for type 304 stainless steel in water–ethanol media containing 2M H₂SO₄

Evaluation of stainless steels for their resistance to intergranular corrosion

Austenitic stainless steels are being considered as structural materials for first wall/blanket systems in the International Thermonuclear Reactor (ITER). The uniform corrosion of stainless steels in water is well known and is not a critical issue limiting its application for the ITER design. The sensitivity of austenitic steels to intergranular corrosion (IGC) can be estimated rather accurately by means of calculation methods, considering structure and chemical composition of steel. There is a maximum permissible carbon content level, at which sensitization of stainless steel is eliminated: K = Cr eff − αC eff, where α-thermodynamic coefficient, Cr eff-effective chromium content (regarding molybdenum influence) and C eff-effective carbon content (taking into account nickel and stabilizing elements). Corrosion tests for 16Cr11Ni3MoTi, 316L and 316LN steel specimens, irradiated up to 2 × 10 22 n/cm 2 fluence have proved the effectiveness of this calculation technique for determination of austenitic steels tendency to IGC. This method is directly applicable in austenitic stainless steel production and enables one to exclude complicated experiments on determination of stainless steel susceptibility to IGC.

The stress corrosion cracking of heavily sensitized type 316 stainless steel in water in the temperature range 50–100°C

The susceptibility to stress corrosion cracking of a Type 316 stainless steel tubing material which had been sensitized in a steam generating rig operated at temperatures from 502 to 533°C was assessed using the slow strain rate technique. The experiments were performed in de-aerated and in oxygenated water with and without chloride additions and in the temperature range 50–100°C. The material was susceptible to stress corrosion cracking and to mechanically induced cracking during dynamic straining. Susceptibility to stress corrosion cracking increased with increasing temperature and with increasing oxygen and chloride contents. Cracking occurred with greater than 200 ppb oxygen present even when the chloride content was less than 5 ppb. The maximum allowable oxygen content decreased further when the chloride content was increased. The maximum chloride content for immunity to stress corrosion cracking was 5 ppm even when less than 5 ppb oxygen was present in the water. The severe susceptibility of the material was caused by the complicated metallurgical state of the inner tube surface, but cracking could be prevented by appropriate potentiostatic control.

SCC Analysis of Austenitic Stainless Steels in Chloride-Bearing Water by Neural Network Techniques

Abstract Although case histories, reflecting engineers' experiences with chloride-induced stress corrosion cracking of austenitic stainless steels in water, are multifold, this source of informatio...

The stress corrosion cracking behaviour of annealed 316 stainless steel in low oxygen 5 ppm chloride content water at 300°C

Stress corrosion cracking tests on annealed 316 stainless steel in water containing 5 ppm Cl− and <5 ppb O2 at 300°C have been conducted at a strain rate of 1.8 × 10−6 s−1. The tests were performed in a low flow rate refreshed autoclave loop under potentiostatic control. Stress corrosion cracking of the steel in 300°C water occurred in two ranges of electrochemical potential; >100 mV and −200 to −450 mV (SHE). The mechanism of stress corrosion cracking in the two potential ranges was anodic dissolution controlled. Crack initiation in the potential range −200 to −450 mV resulted from the presence of a thick magnetite film. The initiation and propagation of stress corrosion cracks in these water conditions is discussed; it is concluded that the surface state of the material is important in determining whether stress corrosion cracks are formed during slow strain rate tests.

The influences of vapor environment and temperature on the contact angle-drop size relationship

Advancing contact angles have been measured for the systems water-PTFE, water-copper, water-stainless steel, n-decane-PTFE, n-undecane-PTFE, and cyclohexane-PTFE using drop sizes varying in base diameter from 1–15 mm. For the water-PTFE/copper/stainless steel systems, a decrease in contact angle with decreasing drop size is observed in saturated argon or nitrogen at 25°C. An increase in contact angle, however, occurs with decreasing drop size at the boiling point for water drops residing on Teflon PTFE and copper in its vapor. For n-decane and n-undecane drops on a Teflon PTFE surface in argon saturated with their respective vapors at 25°C no change of contact angle with drop size is observed. However, for cyclohexane there is a change which is attributed to surface absorption. In further experiments where the water drops residing on a PTFE surface were surrounded by n-decane, n-undecane, or cyclohexane saturated argon vapors at 25°C no change of contact angle with different environments is detected, demonstrating that the equilibrium film pressure is negligible.

高温の水蒸気/酸素雰囲気におけるSUS 430ステンレス鋼の breakaway 挙動

高温の水蒸気/酸素雰囲気におけるSUS 430ステンレス鋼の breakaway 挙動

Stress corrosion cracking of SUS 304 stainless steel in water at high temperatures — effects of solution temperature and sensitisation treatment

Stress corrosion cracking of SUS 304 stainless steel in water at high temperatures — effects of solution temperature and sensitisation treatment

The influence of environment on the drop size ? contact angle relationship

Advancing contact angles are reported for the water-PTFE, water-copper, water-stainless steel, water-PMMA andn-decane-PTFE systems for a range of liquid drop sizes.

The Effect of Dissolved Oxygen and NO3− Anions on the Stress Corrosion Cracking of Type 304 Stainless Steel in Water at 290 C

Abstract The effect of dissolved oxygen and NO3− anions on the intergranular stress corrosion cracking (IGSCC) and transgranular stress corrosion cracking (TGSCC) of Type 304 stainless steel has been studied in water at 290 C by using the constant extension rate tests (CERT) method. A strain rate of 3.33×10−6 sec−1 was applied. TGSCC occurred in water containing less than 100 ppb dissolved oxygen, while IGSCC occurred at concentrations greater than 1 ppm dissolved oxygen. IGSCC was accelerated by the addition of small amounts of NO3− anions, but TGSCC was suppressed by the presence of this anion. The analyses of oxide films by the Ion Microprobe Mass Analyzer (IMMA) and the construction of potential-pH diagrams for Cr-H2O, Ni-H2O, and Fe-H2O systems at 290 C were performed to consider the effect of dissolved oxygen and NO3− anions on IGSCC and TGSCC. The IMMA studies revealed that the compositions of the oxide films of Type 304 stainless steel and Fe-12Cr-9.3Ni steel (the presumed composition of grain boundaries in sensitized Type 304 stainless steel) were Cr-enriched at 200 ppb O2 level. At 1 ppm O2 level, the oxide film of Type 304 stainless steel was composed of Cr-enriched phase, but the Cr content in the oxide film of Fe-12Cr-9.3Ni steel was low. At 10 ppm O2 level, the oxide film of Type 304 stainless steel was composed of Fe and Cr, but the oxide film of Fe-12Cr-9.3Ni steel was mainly composed of Fe. The potential-pH diagram for the Cr-H2O system at 290 C indicated that the corrosion potential of Type 304 stainless steel lay in the stable potential region of Cr2O3 at low oxygen levels. On the other hand, at high oxygen levels, the corrosion potential of Type 304 stainless steel lies near the unstable potential region of Cr2O3. This unstable region corresponds to the potential at which Cr2O3 dissolves as dichromate ion (Cr2O7−−) or chromate ion (CrO4−−). The relationship between the characteristics of oxide films and the IGSCC and TGSCC of sensitized Type 304 stainless steel is discussed.

Numerical integration method for reflected beam profiles near Rayleigh angle

A numerical integration method is devoloped to calculate the intensity profile of an ultrasonic beam reflected from a liquid–solid interface. This numerical treatment is used to calculate nonspecular reflectivity at a range of angles of incidence near and at the Rayleigh angle. Calculations for a water–stainless steel interface are compared to a known approximate analysis for various beamwidths and frequencies. The theoretical predictions of the reflected beam profile near the Rayleigh angle of incidence are compared to experimental results.

Reflection of a Gaussian ultrasonic beam from Al2O3 layer–stainless steel in water at the Rayleigh angle

The problem of ultrasonic wave reflection at a Rayleigh angle from Al2O3 layer–stainless steel in water was investigated. The so-called leaky Rayleigh velocity was measured by using an optical schlieren technique to identify the Rayleigh angle. The magnitude of the measured leaky Rayleigh velocity for the coated surface is smaller than the corresponding leaky Rayleigh velocity for either stainless steel or for Al2O3.

Stress Corrosion Crack Growth in Austenitic Stainless Steel

Abstract Stress corrosion crack velocity and stress corrosion threshold stress intensity have been measured for Type 304L austenitic stainless steel in water with 42% MgCl2 at 130 C. The stress corrosion crack velocity vs stress intensity curve has a shape similar to the one for other austenitic steels and many other metallic and nonmetallic materials. The threshold stress intensity (KISCC is 8 ± 1 MN·m−3/2, and the plateau crack velocity is 3 to 6 × 10−8 m/s. Linear elastic fracture mechanics techniques can be applied to SCC testing of soft and tough materials, provided the KISCC is low enough, and crack branching can be avoided. Criteria for the formation of single, branched, and circular stress corrosion cracks are indicated.

Reflection of a Gaussian ultrasonic beam from a liquid-solid interface

A Gaussian distribution of amplitudes in an ultrasonic beam reflected from liquid-solid interfaces is used in the reexamination of the concept of “beam displacement” which occurs at the angle of excitation of surface waves on the interface. Experimental results show that the energy of the reflected beam is redistributed into two or more beams at (or near) this angle. The theory of Brekhovskikh has been extended to include both a Gaussian input beam and the second derivative of the phase shift upon reflection. Reasonable agreement is obtained between theory and experiment for water-aluminum and water-brass interfaces. For water-beryllium and water-stainless steel the agreement is fair.

高温水中における18Crステンレス鋼の酸化被膜構造におよぼす冷間加工の影響

Effects of cold working on the structures and chemical compositions of oxide films of 18Cr stainless steel in water at 300°C were investigated.Main results obtained are as follows:After the non-deformed sample had been heated in water at 300°C for 1 hr, oxide films composed of corundum type oxide containing Fe and Cr were formed on the surface of the sample. When the sample deformed 5% or 15% by tension was heated under the same oxidizing condition, oxide films consisting of not only the corundum type but also the spinel type oxides were produced on the surface of the sample and the spinel type oxide in the films increased with increasing tensile strain.The oxide films formed in water at 300°C on the sample which had been deformed 15% by tension and annealed to relieve the stress, were composed of the corundum type oxide only.In the initial stage of the oxidation in high temperature water (150°C), the surface of the sample was covered with oxide films consisting of the corundum type oxide containing Fe and Cr, regardless of whether the sample was deformed by tension or not.

Phase Measurements of Reflected Ultrasonic Waves near the Rayleigh Critical Angle

The phase shift with incident angle of reflected ultrasonic waves incident near the Rayleigh critical angle is reported. These measurements substantiate the predictions of our model. These predictions differ substantially from previous theories which neglect attenuation. For frequencies above 15 MHz the slope of the phase shift of an ultrasonic wave reflected from a water-stainless steel boundary reverses at the Rayleigh critical angle. For frequencies below 15 MHz the phase shifts from 0° to +360°; above 15 MHz it shifts from 0° to +60° then to −60° and back to zero again on passing through the Rayleigh critical angle. The sensitivity of this phenomenon suggests that it could be useful in determining or evaluating changes in material properties such as cold work, residual stress, or grain sizes.

Technique for Studying the Kinetics of Intergranular Crack Nucleation on AISI Type 304 Stainless Steel in Oxygenated Water at 289 C

Abstract The design of a system with which to study the kinetics of intergranular crack nucleation on Type 304 stainless steel in water containing 100 ppm O2 at 289 C (554 F) is described. A bellows loading system capable of holding samples in simple uniaxial tension is discussed, and the results of constant load experiments on sensitized Type 304 stainless steel are presented. The elongation-time behavior of the above material is characterized by a distinct “stair-step” type of curve which is taken to indicate the presence of a mechanical event in the cracking mechanism. The nucleation or induction time, Tn, is shown to increase markedly as the applied stress was decreased from 30 to 20 kpsi. Cathodic protection inhibits crack initiation indefinitely, thereby indicating the presence of an electrochemical event in the cracking mechanism. Crack nuclei are shown to be associated with regions of plastic deformation, and can in certain instances initiate and propagate transgranularly down carbide decorated sl...

高温塩化物水溶液中におけるオーステナイトステンレス鋼の応力腐食割れ感受性におよぼす合金組成の影響

The comparison of stress corrosion cracking behaviors of four types of commercial austenitic stainless steel in high temperature water was studied. Tests were made at the temperature of 300° and 350°C for 300 hr in an autoclave containing the testing water with 100∼800 ppm of chloride ion added as NaCl. The amount of dissolved oxygen in water was controlled with or without deaeration at the temperatures of 105° and 150°C, respectively. The results were summarized as follows: (1) Neither of the steels showed no stress corrosion cracking provided that the concentration of dissolved oxygen in the testing water did not exceed 0.2 ppm, but cracking was observed on all the types of stainless steel in the water with a concentration of dissolved oxygen higher than 0.3 ppm. (2) Among the solution treated steels, the type SUS 32 was most resistant, and the susceptibility of other types were almost the same. (3) Sensitizing heat treatment markedly increased the susceptibility of cracking for all the types of steels. (4) The cracking was transgranular in the solution treated steels independently of the difference in composition, but the intergranular cracking was also observed in the sensitized type SUS 27 and 32 steels. (5) From the observation on the pitting corrosion formed on the test pieces and also from the metallographic inspection of pits and cracks, it appears that pitting is the cause of initiation of cracking. (6) The results of cracking tests in a boiling 42%MgCl2 aqueous solution did not agree with those in high temperature water in regard to the process of initiation or path of cracking, and also the difference in susceptibility of cracking for the four types of steel was noticed between the two testing methods.