Cr Stainless Steel Research Articles

Effect of Laser Surface Melting on Microstructure and Performance of Super 13Cr Stainless Steel

Effect of Laser Surface Melting on Microstructure and Performance of Super 13Cr Stainless Steel

Corrosion behaviour of 13Cr stainless steel under stress and crevice in 3.5 wt.% NaCl solution

The corrosion behaviour of 13Cr stainless steel under stress and crevice in 3.5 wt.% NaCl solution was studied by electrochemical measurements. It is demonstrated that the applied stress degrades the passive film, resulting in negative shift of pitting potential and enhanced susceptibility of pitting corrosion. The crevice corrosion of 13Cr stainless steel involves three stages: induction period, rapid development period and stable development period. In the coexistence of crevice and stress, the enhanced anodic reaction by applied stress accelerates the accumulation of H+ and Cl− ions inside crevice, which shortens the induction period and promotes the propagation of crevice corrosion.

Evolution and characterization of the film formed on super 13Cr stainless steel in CO2-saturated formation water at high temperature

The evolution and characterization of films formed on super 13Cr at 90 °C and 200 °C were investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Focus Ion Beam (FIB) and Transmission Electron Microscopy (TEM) and localized Raman spectroscopy. The results show that super 13Cr maintains a passive state at 90 °C, while an active state exists with a high corrosion rate of 0.43 mm/year at 200 °C for the first 5 h, then stabilizes to a rate of 0.125 mm/year over 5 days exposure. The passive film formed at 90 °C is an amorphous-like structure with high Cr content, while the corrosion product films formed at 200 °C are mainly comprised of nanocrystalline spinel FeCr2O4 and crystalline FeCO3.

Corrosion Inhibition of 13Cr Stainless Steel in HCl/HAc/HF Acid Solution

Corrosion Inhibition of 13Cr Stainless Steel in HCl/HAc/HF Acid Solution

Rapid Pitting Corrosion Failure Analysis of 13Cr Stainless Steel as Thermocouple Protecting Material in Dry Gas Pipeline

This paper presents corrosion failure analysis of 13Cr stainless steel (SS) in gas pipeline ingas pipeline, which was used as thermocouple protecting material (TPM). A portion of TMP faileddue to pitting corrosion under unknown circumstances. Scanning electron microscopy (SEM) andX-ray diffraction (XRD) are employed to characterize the scales and/or corrosion products near thefailed portion. Based on visual and microscopic analyses, reviewing the background information andthe thermodynamic calculation, the following rapid pitting corrosion failure sequences wereidentified: Once the pitting appeared, in addition to the gas leakage and expansion, the temperaturedrop should lead a small amount of water in dry gas to condense on the surface of TPM. On one hand,the high salinity produced water will corrode the thermocouple. On the other hand, the high salinityproduced water will pass into the annular space of TPM through the pitting because of the pressuredrop, and the water will stay on inner surface for more time than that of external surface, whichaccelerated pitting of TPM. More and more pitting appeared, and the surface roughness increased.The film-forming property of condensation water will also increase. So, the TPM will be scrappedsoon.

Effect of Cl− Concentration on the SCC Behavior of 13Cr Stainless Steel in High-Pressure CO2 Environment

An effect of Cl− concentration on the stress corrosion cracking (SCC) behavior of 13Cr stainless steel was investigated by employing electrochemical measurements and the slow strain rate tensile tests. These tests were conducted in various solutions with different concentrations of NaCl at 90 °C under 3 MPa CO2 with 3 MPa N2. The results indicate that the passive film of the specimen formed in the 10% NaCl solution has the best protective effect on the matrix. The SCC susceptibility does not increase with increasing the chloride ion concentration, the lowest SCC susceptibility occurs when the NaCl concentration is 10%, and the specimens show higher SCC susceptibility in the 5% NaCl and 20% NaCl solutions.

Research on microstructure transformation and property of 18Cr–0.2C Fe-based coatings

ABSTRACTIn this study, the coatings were fabricated on the 3Cr13 stainless steel substrate by laser cladding. The microstructure, phase compositions and the detailed information about the crack propagation of the coatings were investigated systematically. A comparative study on the corrosion resistance of the traditional of 3Cr13 stainless steel and laser cladding blades was conducted. The standard Gibbs free energy variation of carbides, phase composition and precipitation sequence were precisely calculated. The results showed that the microstructure near the fusion zone was mainly composed of cellular crystals and dendrites. Meanwhile, its microstructure had changed in the upper middle of the coatings. The calculated results showed that the phases formed at the equilibrium state consisted of α-Ferrite, σ and M23C6 carbide. In the vicinity of fusion line and the middle of the coatings, the crack distributed along α-Ferrite grain boundaries. On the top of coatings, the crack traversed the matrix and carbide.

Micro-scale Observation of Corrosion of Hot-Dip Aluminized 11% Cr Stainless Steel

Micro-scale Observation of Corrosion of Hot-Dip Aluminized 11% Cr Stainless Steel

Research on the Main Controlling Factor of Transformation Among M3C, M7C3 and M23C6 Carbides

Based on the limitations of traditional viewpoint that the carbide types in chromium wear-resistant alloys were determined by the Cr/C value, the aim of this study was to reveal the mechanism of recombination-reconstruction between different atoms and the influence of various elements on the formation of carbide types during the mutual transformation of M3C, M7C3 and M23C6 carbides by analyzing the difference of carbide types in different Fe-Cr-C alloys and the transformation characteristics of carbide types before and after carburization and decarbonization of 3Cr13 stainless steel. The viewpoints were put forward as follows: the transformation between M3C and M7C3 carbides are predominantly controlled by the chromium content, and the main controlling factor of transformation between M7C3 and M23C6 carbides is the carbon content. In the different stages of carbide transformation, the chromium and carbon play the main controlling role respectively

Influence of Scanning Speed on Microstructure and Properties of Laser Cladded Fe-Based Amorphous Coatings.

Fe-based amorphous alloys with excellent mechanical properties are suitable for preparing wear resistant coatings by laser cladding. In this study, a novel Fe-based amorphous coating was prepared by laser cladding on 3Cr13 stainless steel substrates. The influence of scanning speeds on the microstructures and properties of the coatings was investigated. The microstructure compositions and phases were analyzed by scanning electron microscope, electron probe microanalyzer, and x-ray diffraction respectively. Results showed that the microstructures of the coatings changed significantly with the increase of scanning speeds. For a scanning speed of 6 mm/s, the cladding layer was a mixture of amorphous and crystalline regions. For a scanning speed of 8 mm/s, the cladding layer was mainly composed of block grain structures. For a scanning speed of 10 mm/s, the cladding layer was composed entirely of dendrites. Different dilution rates at the bonding zones were the main reasons for the microstructure change for different claddings. For all three scanning speeds, the coatings had higher hardness and wear resistance when compared with the substrate; as the scanning speed increased, the hardness and wear resistance of the coatings gradually decreased due to the change in microstructure.

Passivity breakdown of 13Cr stainless steel under high chloride and CO2 environment

Herein, the effect of high chloride ion (Cl−) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl− concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl− concentration on the corrosion potential (Ecorr), passive breakdown potential (Epit), and repassivation potential (Erep). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl− concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl− concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl− concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film.

Effect of extremely high CO2 pressure on the formation of the corrosion film on 13Cr stainless steel.

The corrosion behaviors of 13Cr martensitic steel under different CO2 partial pressures (4–28 MPa) were investigated by weight loss tests and surface characterizations. The results show that the corrosion rate of 13Cr steel shows a sharp increase under higher CO2 pressure (28 MPa), which reached approximately 20–180 times as large as those under lower CO2 pressures (4–12 MPa). Under the lower CO2 pressures, a single-layered Cr(OH)3 passive film forms and completely covers the steel surface. However, when the CO2 pressure reaches 28 MPa, a very different corrosion film which contains an inner Cr(OH)3 passive layer and an outer FeCO3 layer forms, and the inner passive layer shows local damage. This phenomenon can be explained by the lower pH (∼2.75) and the higher H2CO3 concentration in the solution under the higher CO2 pressure.

Effects of Heat Treatments on the Corrosion Behavior of 13Cr Stainless Steels in Chloride Solutions Containing Carbon Dioxide

Various electrochemical measurements were adopted to explore the effects of heat treatments on the corrosion resistance of 13Cr martensitic stainless steels in Cl– solutions containing carbon dioxide. Phase contents and lattice strains were measured by Matlab image processing and X-ray diffraction, respectively. The compositions of passive film were tested by X-ray photoelectron spectroscopy. The results showed that the enhancement of austenitized temperature can improve the pitting resistance, whereas uniform corrosion resistance can be injured by the formation of retained austenite. The quenched specimen exhibited enhanced passivation stability in long-term immersion tests. Tempering at 280°C as the optimum process can guarantee 13Cr stainless steel a refined microstructure with reasonable internal stress and easy to obtain an intact protective passive film, which can serviced in complicated CO2 and Cl– corrosion environment.

La2O3 addition for improving the brazed joints of WC-Co/1Cr13

The effects of lanthanum oxide (La2O3) as an interlayer component on microstructures and mechanical properties of brazed joints of tungsten carbide/cobalt (WC-Co) cemented carbides and the 1Cr13 stainless steel are investigated by an integrated experimental and computational thermodynamics approach. A carbide solid solution phase (CSSP) is experimentally identified adjacent to the detrimental η phase (Co3W3C) due to the addition of La2O3. Such a CSSP is observed to suppress the formation of η phase. The underlying inhibition mechanism is then explained thermodynamically by comparing the Gibbs free energy of the austenite, CSSP and η phases. The added La2O3 is also found to effectively promote the heterogeneous nucleation of the austenite phase, which results in the grain refinement and the uniform distribution of the austenite phase. The shear strength (∼340 MPa) of the brazed joints with La2O3 addition outperforms the counterparts without La2O3.

Effects of laser shock peening on corrosion fatigue behavior of 2Cr13 stainless steel

Effects of laser shock peening (LSP) with different coverage layers on corrosion fatigue (CF) resistance of 2Cr13 stainless steel were investigated by residual stress measuring, corrosion fatigue testing and fatigue fracture morphology observing. The results show that LSP can induce high compressive residual stress on the surface of 2Cr13 stainless steel, and the value of surface compressive residual stress increases with the increase of LSP coverage layer. The CF life of LSP specimens is much larger than that of as-machined specimens, and it increases with the increase of LSP coverage layers; the CF crack growth rate of LSP specimens decrease compared with that of as-machined specimens, and it decreases with the increase of LSP coverage layers. After the analysis, we can conclude that the fatigue fracture surface of as-machined specimens is flat and contains few secondary cracks. However, for LSP specimens, due to high surface compressive residual stress induced by LSP, the growth of corrosion fatigue crack is effectively restrained, resulting in a river pattern morphology.

Galvanic corrosion between N80 carbon steel and 13Cr stainless steel under supercritical CO2 conditions

The galvanic effect between N80 carbon steel and 13Cr stainless steel in formation water under supercritical CO2 conditions was studied by electrochemical measurements and surface characterization. It is demonstrated that the galvanic effect obviously promotes the corrosion of N80 carbon steel and lowers the protection of corrosion products under static and dynamic conditions. The fluid flow under dynamic conditions not only accelerates the corrosion of N80 carbon steel, but also strengthens the galvanic effect with higher galvanic current density. The galvanic current density decreases with increasing immersion time due to the decrease of potential difference and the increase of resistance.

Effect of Electric Potentials on Microstructure, Corrosion and Wear Characteristic of the Nitrided Layer Prepared on 2Cr13 Stainless Steel by Plasma Nitriding

Plasma nitriding is a widely used technology to enhance the surface performance and extend the service life of alloy parts. The current research mainly focuses on the influences of time, temperature, gas type and pressure parameters on nitriding behavior, while fewer studies have been conducted on the electric potential. This paper mainly reports the effect of the electric potential on nitriding behavior. Test conditions were set using cathodic, anodic and floating potentials in a plasma nitriding furnace. 2Cr13 stainless steel was nitrided at 450 °C for 5 h in an NH3 atmosphere. The experimental results show that the nitriding treatment can be well performed under the different electric potentials, but differences exist in microstructures, morphologies and performance results of the modified layers. The thickness and hardness values of the nitrided layer are ranked as follows: cathodic > anodic > floating potential. The anodic nitrided surface has an obvious particle deposition layer composed of nitrides and oxides. Electrochemical and tribological experiments show that the corrosion resistance and wear resistance were significantly improved after a nitriding treatment using the three electric potentials. Moreover, the floating nitriding treatment resulted in the best tribological performance and corrosion resistance.

Gray Relationship Analysis on Corrosion Behavior of Super 13Cr Stainless Steel in Environments of Marine Oil and Gas Field

Gray Relationship Analysis on Corrosion Behavior of Super 13Cr Stainless Steel in Environments of Marine Oil and Gas Field

Inhibitive effects of inhibitors on the galvanic corrosion between N80 carbon steel and 13Cr stainless steel under dynamic supercritical CO2 conditions

The inhibitive effects of imidazoline (IM), 1-butyl-2-thiobenzylbenzimidazole (BTBBI) and lauric acid (LA) on the galvanic corrosion between N80 carbon steel and 13Cr stainless steel in oilfield produced water under dynamic supercritical CO2 conditions were studied by weight loss and electrochemical measurements, and surface analysis. It is demonstrated that IM, BTBBI and LA could alleviate the galvanic corrosion of N80 carbon steel coupled with 13Cr stainless steel with the order of inhibitive effects: IM > BTBBI > LA. However, the galvanic effect between N80 carbon steel and 13Cr stainless steel decreases the inhibitive effects of inhibitors.

A New Method for Predicting Erosion Damage of Suddenly Contracted Pipe Impacted by Particle Cluster via CFD-DEM.

A numerical study on the erosion of particle clusters in an abrupt pipe was conducted by means of the combined computational fluid dynamics (CFD) and discrete element methods (DEM). Furthermore, a particle-wall extrusion model and a criterion for judging particle collision interference were developed to classify and calculate the erosion rate caused by different interparticle collision mechanisms in a cluster. Meanwhile, a full-scale pipe flow experiment was conducted to confirm the effect of a particle cluster on the erosion rate and to verify the calculated results. The reducing wall was made of super 13Cr stainless steel materials and the round ceramsite as an impact particle was 0.65 mm in diameter and 1850 kg/m3 in density. The results included an erosion depth, particle-wall contact parameters, and a velocity decay rate of colliding particles along the radial direction at the target surface. Subsequently, the effect of interparticle collision mechanisms on particle cluster erosion was discussed. The calculated results demonstrate that collision interference between particles during one cluster impact was more likely to appear on the surface with large particle impact angles. This collision process between the rebounded particles and the following particles not only consumed the kinetic energy but also changed the impact angle of the following particles.