Cr Stainless Steel Research Articles

Electrochemical Study of Pitting Corrosion of Corrosion Resistant Alloys in Supercritical CO2 Environment

Various types of corrosion resistance alloys such as 13 Cr, Super 13 Cr, and duplex stainless steels are typically used in oil and gas and CO2 capture and storage applications, especially the injection section, where the pipeline could be exposed to aqueous phase and the risk of localized corrosion is of high concern. The composition of these materials is engineered to provide high corrosion-resistant properties. The operating conditions in the above-mentioned applications can include high CO2 pressure and high temperature leading to the “so-called” supercritical CO2 condition. Under the supercritical CO2 conditions, the pH of the aqueous phase in the system can be as low as pH ~ 3 buffered by the dissolved CO2. The environment can also contain high salinity, and therefore, the passive layer on the stainless steel might be locally damaged resulting in pitting corrosion. While there are numerous studies available on the localized corrosion of different stainless steels in chloride-containing aqueous environment, the number of studies in supercritical CO2 conditions is limited. The objective of this work is to understand the effect of supercritical CO2 on the localized corrosion mechanism of corrosion resistant alloys.Three different types of corrosion resistant alloys (13 Cr, Super 13 Cr, and duplex stainless steel) are studied under CO2 pressure (0 to 14 MPa) and at high temperature (150˚C) in 5 wt.% NaCl solution. The experiments are conducted in a high-pressure autoclave system at a consistent initial pH for comparison. The electrochemical behavior and the pitting corrosion are studied using cyclic potentiodynamic polarization and potentiostatic measurements. The surface of each specimen is investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) before and after the electrochemical experiments to characterize the microstructural and localized corrosion features, respectively. All the tested materials show passive behavior under the conditions of the current study, however the pitting potential decreased in this order: duplex, Super 13 Cr and 13 Cr stainless steel.

Effect of heat treatment process on impact toughness of a Ni-containing stainless steel 3Cr13 Precision Die

Nowadays 3Cr13 martensitic stainless steel is increasingly used for precision molds. However, its low-temperature impact toughness below room temperature requires further improvement. This study investigates the effect of heat treatment process of a Ni-containing at low temperature impact toughness of 3Cr13 stainless steel used for precision die. Various characterization techniques are combined in order to unveil different heat treatment processes on impact toughness. The test results show that after three different heat treatment processes, the low-temperature impact toughness of the investigated steel at 0 ℃ has been greatly improved. After the investigated steel is heated at 1040 ℃ for 15 minutes, then water-cooled quenched, and then heated to 540 ℃ for 30 minutes, the impact fracture is a dimple shaped plastic one, and its low-temperature impact absorbed energy is higher than that of other heat treatment processes. It shows that the holding time under quenching heating temperature and tempering temperature also have important effects on the improvement of low-temperature impact toughness, which provides technical support for heat treatment design for the Ni-alloyed 3Cr13martensitic stainless steel.

Effect of heat treatment process on impact toughness of a Ni-containing stainless steel 3Cr13 Precision Die

Nowadays 3Cr13 martensitic stainless steel is increasingly used for precision molds. However, its low-temperature impact toughness below room temperature requires further improvement. This study investigates the effect of heat treatment process of a Ni-containing at low temperature impact toughness of 3Cr13 stainless steel used for precision die. Various characterization techniques are combined in order to unveil different heat treatment processes on impact toughness. The test results show that after three different heat treatment processes, the low-temperature impact toughness of the investigated steel at 0 ℃ has been greatly improved. After the investigated steel is heated at 1040 ℃ for 15 minutes, then water-cooled quenched, and then heated to 540 ℃ for 30 minutes, the impact fracture is a dimple shaped plastic one, and its low-temperature impact absorbed energy is higher than that of other heat treatment processes. It shows that the holding time under quenching heating temperature and tempering temperature also have important effects on the improvement of low-temperature impact toughness, which provides technical support for heat treatment design for the Ni-alloyed 3Cr13martensitic stainless steel.

Effect of solution aging treatment on microstructure and properties of Fe‐0.5C‐11Cr corrosion resistant alloy by laser cladding

Fe‐0.5C‐11Cr corrosion resistant alloy coating was prepared on the surface of 3Cr13 stainless steel by powder feeding laser cladding, and the microstructure of the coating layer was controlled by solution aging treatment. The microstructure of the coatings was measured by scanning electron microscopy, and phase composition was determined by X-ray diffraction. The hardness and corrosion resistance of coatings before and after heat treatment were evaluated on microhardness tester and electrochemical workstation, respectively. The results show that the morphology, size and quantity of dendrite carbides in the cladding layer of Fe‐0.5C‐11Cr alloy can be improved by solution and aging treatment. The eutectic carbides in the cladding layer can be changed from block, bone, continuous network of grain boundaries to round granular and discontinuous short rod by solution and aging treatment, which greatly improves the uniformity of the microstructure. There is a dynamic equilibrium and critical time for the melting and growth of carbides at 1050 °C. When the holding time is less than 20 min, the size of carbide decreases with time. After 20 min, fine carbides agglomerate and grow with time. The hardness of the cladding layer after heat treatment is about 9% higher than that of the cladding layer without heat treatment and the uniformity of the hardness is improved. The corrosion resistance of the sample kept for 20 min at 1050 ℃ is the superior because the pitting potential and passivation zone width of the coating kept at 1050 ℃ for 20 min increased by 21.5% and 19.2% compared with the cladding laser without heating, respectively.

Tribological properties of copper-embedded self-lubricating bearing materials

PurposeThis study aims to investigate the effects of graphite-MoS2 composite solid lubricant on the tribological properties of copper-based bearing materials under dry conditions.Design/methodology/approachThe mixture of Graphite-MoS2 was inlaid in ZQSn6-6–3 tin bronze and ZQAl9-4 aluminum bronze matrix. These copper-embedded self-lubricating bearing materials were considered in friction pairs with 2Cr13 stainless steel, and their tribological properties were studied by using an MM200 wear test machine.FindingsThe results show that the friction coefficients and wear rates of copper-embedded self-lubricating bearing materials are lower than those of the ordinary copper-based bearing materials. The wear performance of the tin bronze inlaid self-lubricating bearing material is better than that of the aluminum bronze inlaid self-lubricating bearing material. The wear mechanism of the tin bronze bearing material is mainly adhesive wear, and that of the aluminum bronze bearing material is mainly grinding wear, oxidation wear and adhesive wear. The copper-embedded self-lubricating bearing materials had no obvious abrasion, whereas the aluminum bronze inlaid self-lubricating bearing material exhibited deep furrows and obvious abrasion under high loads.Originality/valueThese results are helpful for the application of copper-embedded self-lubricating bearing materials.

One-step modification method of a superhydrophobic surface for excellent antibacterial capability

In this study, micro/nanostructures are fabricated on the surface of 3Cr13 stainless steel via laser etching, and a superhydrophobic coating with silver nanoparticles (AgNPs) is prepared by utilizing the reduction-adsorption properties of polydopamine (PDA). We investigate the effect of soaking time from the “one-step method” on the reduction of nano-Ag, surface wettability, and antibacterial properties. Scanning electron microscopy is performed to analyze the distribution of nano-Ag on the surface, whereas X-ray energy dispersive spectroscopy and X-ray photoelectron spectroscopy are used to analyze the crystal structures and chemical compositions of different surfaces. Samples deposited with PDA on their surface are soaked in a 1H,1H,2H,2H-perfluorodecyltriethoxysilane water-alcohol solution containing AgNO3 for 3 h. Subsequently, a “one-step method” is used to prepare low-adhesion superhydrophobic surfaces containing AgNPs. As immersion progresses, more AgNPs are deposited onto the surface. Compared with the polished surface, the samples prepared via the “one-step method” show significant antibacterial properties against both gram-negative Escherichia coli and gram-positive Staphylococcus aureus. The antibacterial properties of the surface improve as immersion progresses.

Microstructure and Mechanical Properties of Ti-Alloyed Supermartensitic 12%Cr Stainless Steel Classes 95 ksi and 110 ksi for Oil and Gas Production

Microstructure and Mechanical Properties of Ti-Alloyed Supermartensitic 12%Cr Stainless Steel Classes 95 ksi and 110 ksi for Oil and Gas Production

Effects of operating conditions on corrosion behaviour of 13% Cr stainless steel in H2S environment

Effects of operating conditions on corrosion behaviour of 13% Cr stainless steel in H2S environment

Effects of flow velocity on the corrosion behaviour of super 13Cr stainless steel in ultra-HTHP CO2–H2S coexistence environment

The corrosion behavior of super 13Cr SS under the effect of flow velocity in the ultra-HTHP supercritical CO2–H2S–Cl- environment was investigated. The results show the morphology and composition of the corrosion products of super 13Cr SS samples change with varying flow state. In the static condition, the layer consists of an inner layer of Cr(OH)3, a middle layer of Fe1−xS, and an outer crystalline FeCO3 layer. However, in the dynamic supercritical CO2 phase, a galvanic couple effect exists between the pyrrhotite and uncovered steel. Meanwhile, the velocity delays the deposition of FeCO3 and promotes the development of pitting.

Effect of electric potentials on high‐temperature plasma nitriding of 2Cr13 stainless steel with active screen assisted

AbstractThe influence of electric potentials on the characteristics of modified layers with plasma nitriding of 2Cr13 stainless steel at a high temperature was investigated. Three active screens were placed on the cathodic plate. Three groups of 2Cr13 stainless steel samples were set with cathodic, anodic, and floating potentials. Samples were nitrided at 500 °C for 5 h in an ammonia atmosphere. The treated samples were analyzed using x‐ray diffraction, scanning electron microscopy with energy dispersive x‐ray spectroscopy, surface roughness tester, and atomic force microscopy. It is proved that nitriding treatments can be suitably carried out at three electric potentials, but the corresponding modified layers take on different microstructure, morphology, and hardness behaviors. It found that the three nitrided samples are mainly composed of the ϵ−Fe2‐3N and γ’−Fe4N phases. The order of thicknesses of the nitrided layers is: floating < anodic < cathodic potential. The results also demonstrated that electric potentials play essential roles in the corrosion resistance and tribological properties in plasma nitriding treatment. Because there is no visible precipitation of chromium nitride in the modified layer, the corrosion resistance of the floating nitrided sample is better than that of the other two samples.

Formation and Evolution of the Corrosion Scales on Super 13Cr Stainless Steel in a Formate Completion Fluid With Aggressive Substances

The formation and evolution of the corrosion scales on the super 13Cr stainless steel (SS) surface after exposure in a formate completion fluid with the presence of various aggressive substances was investigated. The results indicate that the formation of Fe3O4 covered the surface of super 13Cr SS as the inner layer accompanied with outer scattered FeS. The corrosion rate was below 0.07 mm/year after 120 h of exposure in the formate fluid at 180°C under N2 environments; the presence of aggressive substances such as sulfide and CO2 in the formate fluid promoted the proceeding of anodic dissolution in the early period, and the ingress of CO2 progressively increased the general corrosion rate to 1.7 mm/year. For CO2-containing conditions, the formation of FeCr2O4 and Cr(OH)3 was detected in the inner corrosion product layers, and the precipitation of “sheet”-shaped iron carbonate (FeCO3) was detected as the outer layer. The accumulation rate of corrosion products increases by two orders of magnitude with the ingress of CO2, corresponding to thicker corrosion products, but the dissolution rate is still three orders of magnitude higher than when CO2 was absent.

Effect of 12% Mn Addition on Hydrogen Embrittlement Resistance and Corrosion Behavior of Super 13cr Martensitic Stainless Steel

Effect of 12% Mn Addition on Hydrogen Embrittlement Resistance and Corrosion Behavior of Super 13cr Martensitic Stainless Steel

Role of Mn addition on the general corrosion and pitting corrosion behavior of 13Cr stainless steel

PurposeThe purpose of this study is to elucidate the effect of Mn addition on the corrosion behavior of stainless steel.Design/methodology/approachChronoamperometry, quasi-steady-state polarization and electrochemical impedance spectroscopy were used to investigate the corrosion behavior of Mn added A13Cr-HS sample and original S13Cr samples. In addition, the corrosion product film was characterized by a field emission scanning electron microscope equipped with energy-dispersive spectroscopy and X-ray photoelectron spectroscopy.FindingsThe A13Cr-HS sample with 8 wt.% Mn addition maintained good general corrosion resistance in both acidic and alkaline solutions compared to the original S13Cr sample. Additionally, the A13Cr-HS sample had good pitting resistance in an alkaline solution containing Cl−, but a weaker resistance in an acidic solution.Originality/valueThe influence of Mn addition on the formation mechanism of the passive film was systematically analyzed.

Preparation and Wetting Mechanism of Laser‐Etched Composite Self‐Assembled 1H,1H,2H,2H‐Perfluorodecyltriethoxysilane Superhydrophobic Surface Coating

Herein, a grid‐like microstructure is prepared on the surface of 3Cr13 stainless steel through nanosecond laser etching, and the self‐assembled 1H,1H,2H,2H‐perfluorodecyltriethoxysilane (PFDS) coating is further composited to prepare a superhydrophobic surface with a contact angle of 164° and a rolling angle of 3°. The effect of laser etching cycles on the surface microstructure and surface wettability before and after the self‐assembly is studied. With an increase in the etching cycles, a stable grid‐like microstructure is gradually formed on the surface, and subsequently, a composite structure of grooves and pits is formed. After the self‐assembly of the PFDS coating, two superhydrophobic surfaces with different wetting properties are obtained. Furthermore, as the etching cycles increase, the surface changes from a superhydrophobic and high‐adhesion state to a superhydrophobic and low‐adhesion state. The decrease in surface energy is mainly attributed to the C−F group in the PFDS molecule. The experimental results show that PFDS molecules are deposited easily in case of the convex surface, thereby facilitating the formation of superhydrophobic low‐adhesion surfaces. Finally, the superhydrophobic surface is still maintained after cumulative ultrasonic cleaning in deionized water for 75 min, showing good reusability and stability.

Microstructure and Corrosion Resistance of Fe-Cr-Si Alloys

Fe-Cr-Si alloys material has good abrasion resistance, corrosion resistance and high-temperature oxidation resistance, especially the introduction of Si element can further improve its corrosion resistance. In this work, two Fe-Cr-Si alloys with different Si (10wt. % and 12wt. %) contents were designed and prepared by an arc furnace process. The microstructure and corrosion resistance of Fe-Cr-Si alloys were investigated. Results has shown that the Fe-Cr-Si alloys are composed of primary dendrite and interdendrite matrix, and metal silicide Fe3Si formed in the microstructure. Fe-Cr-Si alloys have a wider passivation interval than 2Cr13 stainless steel and the corrosion resistance of the Fe-Cr-Si alloys increased by more than 20 times in 10%HCl solution compare to 2Cr13 stainless steel.\\

Cavitation erosion mechanism of 2Cr13 stainless steel

The erosion mechanism of 2Cr13 stainless steel under ultrasonic cavitation was investigated. The cavitation erosion process investigated in this paper included the incubation period and acceleration period. Microhardness measurement and transmission electron microscopy showed that the surface was deformed and hardened, the grains on the eroded surface layer were refined by nanograins and subgrains. Scanning electron microscopy and electron backscatter diffraction analysis showed that cracks were initiated at the grain boundaries and subgrain boundaries, pits were from the carbide-matrix interfaces and defect microholes, in the incubation period, cracks were grown across the grain into peelings, pits were connected into microholes. In the acceleration period, cracks were initiated at and propagated along the grain boundaries and subgrain boundaries. Kernel average misorientation (KAM) was utilized to show the strain at the grain boundaries and subgrain boundaries and to estimate the density of the geometric necessary dislocations (GNDs) along the depth after cavitation erosion. The thickness of the strain layer after cavitation erosion was not more than 23 μm. The surface fatigue failure was caused by the plastic deformation and stress concentration under the continuous cavitation impacts.

Stress corrosion cracking behavior and mechanism of super 13Cr stainless steel in simulated O2/CO2 containing 3.5 wt% NaCl solution

Good CO2 corrosion resistance has made super 13Cr martensitic stainless steel become widely used in oil industry. However, the corrosion of OCTG (Oil CountryTubular Goods) changes from pure CO2 to O2/CO2/Cl- and other multi-component containing complex environment. To clarify the stress corrosion cracking (SCC) behavior and fracture mechanism of the super 13Cr stainless steel in the corrosive environment containing O2, CO2 and Cl-, the effect of applied potential on the SCC susceptibility of super 13Cr stainless steel in a 10% O2 and 90% CO2 containing 3.5 wt% NaCl solution was investigated by means of potentiodynamic polarization, slow strain rate tensile (SSRT) test and combined with scanning electron microscopy (SEM). The results show that the polarization potential has an influence on the SCC susceptibility of super 13Cr stainless steel in O2/CO2/Cl- containing medium. The SCC susceptibility is high with the anode and cathode polarization applied, and increases with the rise of theabsolute potential values. The SCC mechanism has the following relationships with the applied potentials: a) anodic dissolution happens at 50 mV and 250 mV, b) anodic dissolution and hydrogen embrittlement were observed at −300 mV, and c) hydrogen embrittlement was obtained at −800 mV and −1000 mV.

Hydrogen Embrittlement of Steels in High Pressure H2 Gas and Acidified H2S-saturated Aqueous Brine Solution

Microbiological methanation is planned in an underground natural gas reservoir. For this purpose, hydrogen is stored, which can lead to hydrogen embrittlement of steels. To simulate these field conditions, autoclave tests were performed to clarify the amount of absorbed hydrogen and to test whether this content leads to failure of the steels. Constant load tests and immersion tests with subsequent hydrogen analyses were performed. Tests under constant load have shown that no cracks occur due to hydrogen pressures up to 100 bar and temperatures at 25 °C and 80 °C. In these conditions, the carbon steels absorb a maximum of 0.54 ppm hydrogen, which is well below the embrittlement limit. Austenitic stainless steels absorb much more hydrogen, but these steels also have a higher resistance to hydrogen embrittlement. In H2S saturated solutions, the hydrogen uptake is ten times higher compared to hydrogen gas, which has caused fractures of several steels (high strength carbon steels, Super 13Cr, and Duplex stainless steel 2205).

Structure and Property Modulations of 13Cr Stainless Steel Through Microgravity Solidification and Minor Ce Addition

Solidification controlling and RE doping are effective ways to manipulate the microstructures and performances of 13Cr martensitic stainless steel. In this work by Ying Ruan and co-workers, article number 2100062, the influences of microgravity solidification and Ce addition on microstructure refinement, inclusion spheroidization and mechanical properties of 13Cr steels were explored comparatively.

Influence of parameters related to microstructure, chemical composition and environment characteristics on localized corrosion failure susceptibility of supermartensitic stainless steels

This work investigates the parameters that influence pitting resistance of UNS S41426 martensitic stainless steels. Chemical composition, microstructure, acceptable service temperature, chloride concentration, aeration conditions and pH are considered. Electrochemical techniques were used to assess the localized corrosion of two supermartensitic 13Cr stainless steels in compliance with the same classification standard, at different solution conditions, chloride concentration and temperatures. The results clearly showed higher pitting corrosion resistance for the material 2-S13Cr, which is probably related to the concentration of some alloying elements, such as Cr and Mo. Temperature and chloride concentration increment contributed to pitting corrosion failure, as expected.