Corrosion Rate Of Low Alloy Steel Research Articles

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

Prediction model for corrosion rate of low-alloy steels under atmospheric conditions using machine learning algorithms

Effect of Mo on the Corrosion Resistance of Cr-Containing Steel in a Simulated Tropical Marine Atmospheric Environment

In this manuscript, the effect of Mo addition on the corrosion resistance of the low-alloy steel in a simulated tropical marine atmospheric environment has been studied through microstructure characterization, corrosion immersion experiments, electrochemical measurement, and a series of microscopic characterization methods. The results show that Mo has the ability to reduce the corrosion rate of low-alloy steel in a marine atmospheric environment, with a more pronounced reduction effect observed over longer corrosion periods. The addition of Mo enhances the corrosion product film’s compactness when coupled with Cr, subsequently improving corrosion resistance. Simultaneously, MoO42−, acting as a slow-release ion, can effectively suppress localized corrosion in low-alloy steel. The research findings can offer data support and a theoretical foundation for the design of low-alloy steels with enhanced corrosion resistance in a tropical marine atmospheric environment.

Pseudomonas aeruginosa-accelerated corrosion of Mo-bearing low-alloy steel through molybdenum-mediating chemotaxis and motility

In this work, we found that the microbiologically influenced corrosion of Pseudomonas aeruginosa was mediated by Mo in low-alloy steel. Through immersion experiments, we found that the corrosion rate of low-alloy steel was not decreased with the addition of 1.0 wt% Mo. However, in the presence of P. aeruginosa, the corrosion rate of the 1.0 wt% Mo steel was accelerated, resulting in the development of pits. Confocal laser scanning microscopy images revealed that more biofilm cells adhered on the 1.0 wt% Mo steel surface. The chemotactic behavior and swimming ability of the bacteria were the main reason for the greater biofilm cell adhesion in the presence of Mo. Using an RNA-seq assay, we verified that both chemotaxis and motility together affected the adhesion of biofilm, and their related genes were affected by Mo.

Analysis of Environmental Factors Affecting the Atmospheric Corrosion Rate of Low-Alloy Steel Using Random Forest-Based Models.

As one of the factors (e.g., material properties, surface quality, etc.) influencing the corrosion processes, researchers have always been exploring the role of environmental factors to understand the mechanism of atmospheric corrosion. This study proposes a random forest algorithm-based modeling method that successfully maps both the steel’s chemical composition and environmental factors to the corrosion rate of low-alloy steel under the corresponding environmental conditions. Using the random forest models based on the corrosion data of three different atmospheric environments, the environmental factors were proved to have different importance sequence in determining the environmental corrosivity of open and sheltered exposure test conditions. For each exposure test site, the importance of environmental features to the corrosion rate is also ranked and analyzed. Additionally, the feasibility of the random forest model to predict the corrosion rate of steel samples in the new environment is also demonstrated. The volume and representativeness of the corrosion data in the training data are considered to be the critical factors in determining its prediction performance. The above results prove that machine learning provides a useful tool for the analysis of atmospheric corrosion mechanisms and the evaluation of corrosion resistance.

An improved deep forest model for forecast the outdoor atmospheric corrosion rate of low-alloy steels

The paper proposes a new deep structure model, called Densely Connected Cascade Forest-Weighted K Nearest Neighbors (DCCF-WKNNs), to implement the corrosion data modelling and corrosion knowledge-mining. Firstly, we collect 409 outdoor atmospheric corrosion samples of low-alloy steels as experiment datasets. Then, we give the proposed methods process, including random forests-K nearest neighbors (RF-WKNNs) and DCCF-WKNNs. Finally, we use the collected datasets to verify the performance of the proposed method. The results show that compared with commonly used and advanced machine-learning algorithms such as artificial neural network (ANN), support vector regression (SVR), random forests (RF), and cascade forests (cForest), the proposed method can obtain the best prediction results. In addition, the method can predict the corrosion rates with variations of any one single environmental variable, like pH, temperature, relative humidity, SO2, rainfall or Cl−. By this way, the threshold of each variable, upon which the corrosion rate may have a large change, can be further obtained.

Low-Alloy Steel Corrosion Resistance in Natural Gas Preparation Production Solutions

Corrosion resistance of low-alloy steels 20-KSKh, 07GBK, 06GBF, 13FKhA, 09GSF, and 20 with different overall contents of corrosion-active nonmetallic inclusions (CANI) in process media for preparation and drying moist casing-head gas is studied. A study in a model medium simulating seam water of the Khar’yagin deposit, and in a moist hydrogen sulfide atmosphere for ten days shows that a reduction in CANI reduces the corrosion rate of low-alloy steels in a model medium compared with steel St20 by about a factor of two. In a moist hydrogen sulfide atmosphere after testing a steel 20 surface is coated with a uniform layer of corrosion products; in low-alloy steels, corrosion damage occupies 1–7% of the overall area. The results obtained agree with the role of CANI determined previously in developing overall and local corrosion.

Особенности коррозионно-электрохимического поведения сталей с различным содержанием хрома в углекислотных низкотемпературных средах

The effect of chromium on the corrosion rate of low-alloy steels in carbon dioxide media has been studied by the gravimetric method. The features of the electrochemical corrosion behavior of these steels in the media containing carbon dioxide have been determined

Electrochemical impedance of thin rust film of low-alloy steels

The quality of the rust film formed on the steel is a significant factor in atmospheric corrosion. In the present paper, ion-exchange membranes were adopted to simulate the anion and cation selective permeability of the rust film. The i– E curve and the electrochemical impedance of a carbon steel covered with the ion-exchange membrane were measured to discuss the effect of the ion transfer inside the rust film on the anodic dissolution. The electrochemical impedance of the rust film membrane was measured. The electrochemical impedance of the rust film membrane shows the apparent capacitive behavior. It was found that the film had huge capacitance of order 10 mF cm −2. The resistance of the rust films of Fe–3%Ni, Fe–1%W and Fe–0.6%Mo was large value, indicating that the low ion permeability rate inside the rust film contributed to decreasing the corrosion rate of low-alloy steel.

Study on steel corrosion in different seabed sediments

A series of simulation experiments on carbon steel (A3 steel) and low alloy steel (16 Mn steel) in marine atmosphere (MA), seawater (SW) and seabed sediment (SBS) including rough sea sand, fine sea sand and seabed mud were carried out indoors for a year or so by means of individually hanging plates (IHP) and electrically connected hanging plates (ECHP). The corrosion of steels in SBS was mainly due to the macrogalvanic cell effect. The steel plates at the bottom of SBS, as the anode of a macrogalvanic cell, showed the heaviest corrosion with a corrosion rate of up to 0·12 mm/a, approximately equal to that of steel plates in marine atmosphere.The test results showed that the corrosion rates of A3 and 16 Mn steel in marine environment were in the order: MA>SW>SBS by the IHP method; and MA>SBS>SW by the ECHP method. The corrosion rates of steels in the water/sediment interface were directly proportional to the grain size of the SBS by the ECHP method, but those of steels in the water/sediment interface did not vary with the grain size of SBS by the IHP method. The corrosion rate of low-alloy steel was a little higher than that of carbon steel. The results of this study have important applications for design of offshore steel structures such as oil platform, pier, and port.

水溶液薄膜下の低合金鋼の腐食電位と腐食速度

水溶液薄膜下の低合金鋼の腐食電位と腐食速度

濃硫酸中における耐候性鋼の腐食特性

The atmospheric corrosion of steel is thought to proceed in a concentrated sulfuric acid environment, because ferrous sulfate probably formed by its reaction with SO2 in atmosphere exists under the rust layer and is not oxidized immediately by oxygen supplied through the rust layer. Thus the corrosion characteristics of low-alloy steel in 98% sulfuric acid was investigated in comparison with carbon steel. The conclusions obtained were as follows:(1) The results of the rotating immersion test in 98% sulfuric acid showed that the corrosion rate of low-alloy steel was remarkably lowered with the lapse of time after four weeks of immersion. This behavior is quite different from that of carbon steel.(2) The anodic polarization of low-alloy steel was nearly the same as that of carbon steel in the early stage of immersion. However, as the corrosion progressed, the anodic reaction of low-alloy steel was suppressed more remarkably than that of carbon steel.(3) Corrosion products of both low-alloy steel and carbon steel were FeSO4 n H2O. However, from the analytical results by the X-ray microanalyzer, it was found for low-alloy steel that there was a very thin oxide film containing chromium, copper and other alloying elements in high concentrations at the alloy/iron sulfate interface.(4) Addition of Cl− ion into 98% sulfuric acid lowered the anodic polarization of steel. The role of Cl− ion is thought to destruct the stability of the passive oxide films. The passive film formed on low-alloy steel is more stable than that of carbon steel.From the above experimental results, the corrosion characteristics of steel in concentrated sulfuric acid is quite similar to that of atmospheric corrosion. It is certain that the very thin oxide film existing between the iron sulfate layer and the substrate metal plays a predominant role in the corrosion of steels.