Resistance Of Low-alloy Steels Research Articles

Effect of Mo and Sn co-regulation on low alloy steel corrosion in tropical marine atmosphere

The influence of co-regulating Mo and Sn on the corrosion resistance of low alloy steel in tropical marine atmospheric was investigated. The combined addition of Mo and Sn has been found to significantly improve the corrosion resistance of low alloy steel, augmenting the protective capabilities of the rust layer. This combined addition promotes the formation of protective compounds like α-FeOOH and FeCr2O4 within the alloy rust layer. Furthermore, it facilitates the conversion of Cr, Ni and Cu into corrosion-resistant oxides such as Cr2O3, NiFe2O4 and CuO, thereby enhancing the density of the rust layer. Additionally, as corrosion progresses over time, higher levels of Sn addition lead to increased Sn content within the inner rust layer, consequently bolstering the protective qualities of the rust layer. This comprehensive understanding sheds light on the synergistic effects of Mo and Sn in fortifying the corrosion resistance of low alloy steel, offering insights for the development of advanced corrosion-resistant materials in marine environments.

Effect of Ca-Mg microalloying on corrosion behavior and corrosion resistance of low alloy steel in the marine atmospheric environment

The effect of Ca-Mg microalloying on corrosion behavior of Al deoxidized low alloy steel in the simulated tropical marine atmospheric environments was investigated. The addition improves microstructural characteristics, increasing the corrosion potential by 70±10 mV and decreasing the corrosion rate from 1.66 mm/y to 1.57 mm/y over time. Furthermore, the addition of Ca-Mg has been observed to modify the morphological attributes, population density, dimensional parameters, and electrochemical properties of the prevalent inclusions. This modification is instrumental in shifting the underlying mechanisms that contribute to localized corrosion, which is often precipitated by these inclusions in the steel matrix.

Influence of compound layer on the corrosion resistance of low alloy steel in a 3.5% NaCl solution

Samples of AISI 4140 low alloy steel were nitrided at different conditions by using plasma nitriding. The optical microscopy observation and x-ray diffraction analysis showed that a 3 ∼ 12 μm thick compound layer composed of ε-Fe2–3N and γ′-Fe4N was formed on the surface after nitriding treatments. The corrosion behavior was evaluated by measuring the anodic polarization curves in a 3.5% NaCl solution along with the observation of corroded surfaces and cross-sectional morphologies using optical and scanning electron microscope. The results indicated that the corrosion resistance of low alloy steel was significantly enhanced through the formation of compound layer. The thickness of compound layer was one important factor in determining its corrosion resistance.

Essential role of Si in enhancing corrosion resistance of high strength low alloy steels in marine environment

High strength low alloy steels are extensively applied in marine engineering structures (cross-sea bridge, ocean platform, etc), which are usually subjected to severe corrosion in marine atmosphere. In this work, the corrosion behaviors of 550 MPa-grade high strength low alloy marine steels with varied Si content were studied in simulated marine atmosphere. Results show the increase of Si could significantly facilitate the formation of α-FeOOH and enrichment of Cr and Cu in inner rust layer, making the rust layer compact and cation-selective. Si and Cr can be co-enriched in inner rust layer to form mixed or complex oxides with amorphous network structure, which could greatly improve the compactness and stability of rust layer and thereby enhance the corrosion resistance of low alloy steel.

Influence of Cr(III) on the formation and transformation of corrosion products of steel in marine environments

A fundamental approach is used to better understand the influence of Cr on the resistance of low alloy steel to marine corrosion. It focuses on the formation and transformation of corrosion products of steel in seawater-like electrolytes. Fe(OH)2 precipitates are then prepared by mixing a solution of NaCl, Na2SO4·10H2O, FeCl2·4H2O or FeCl2·4H2O + CrCl3·6H2O (so that Cr = 8% and Fe = 92%), with a solution of NaOH. The initial concentration ratio of reactants, Q=frac{2[{{{rm{Fe}}}}^{2+}]+3[{{{rm{Cr}}}}^{3+}]}{[{{{rm{OH}}}}^{-}]}, is set at Q = 0.88, 1, and 1.136. In a first approach, the obtained aqueous suspension is stirred, at a controlled temperature of 25 ± 0.5 °C, to be oxidized by air. The resulting oxidation product is characterized by XRD and Raman spectroscopy. In a second approach, the Fe(OH)2 precipitates are aged one week in suspension in anoxic conditions, filtered, mixed as a wet paste with glycerol and set as a thin compact layer on the sample holder of a X-ray diffraction system. The oxidation process of Fe(OH)2 is then monitored in situ during the acquisition of the X-ray diffractogram. The obtained results demonstrate that Cr(III) hinders the formation of green rust compounds, hence hindering the formation of γ-FeOOH, i.e., the main oxidation product of green rust compounds. The other oxidation pathways of Fe(OH)2, which lead to Fe3O4 or α-FeOOH, are thus favored. Nevertheless, Cr(III) favors mainly the solid state transformation pathway of Fe(OH)2, thus promoting α-FeOOH via the formation of poorly ordered Fe(III) oxyhydroxides, namely feroxyhyte and ferrihydrite.

The dual nature of Cu content on the corrosion resistance of low alloy steels in sulfuric acid: A time-dependent reversal of corrosion resistance

The corrosion performance of low alloy steels with varying Cu contents (ranging from 0 to 1.2 wt%) was evaluated in a 10 wt% H2SO4 solution at room temperature. By incorporating Cu, the active dissolution of the bare steel is effectively suppressed, leading to enhance corrosion resistance as the Cu content increases. However, during immersion, the corrosion product film transitions from CuO and Cu(OH)2 dominance to Cu2O and Cu0 dominance. Simultaneously, hydrogen reduction induces cracks in the film, causing an uneven Cu distribution and gradual corrosion resistance degradation with higher Cu content and longer immersion duration.

Investigation of rust layer on low alloy steel with 0.40 wt% Sn in a rural atmospheric environment

This study investigates the formation and properties of rust layers on low alloy steel containing 0.40 wt% tin (Sn) in rural atmospheric environments. The rust layer was analyzed using various techniques, including scanning electron microscopy, X-ray diffraction and Raman spectroscopy. Additionally, a new corrosion big data sensor was used to evaluate the corrosion resistance of Sn-containing low alloy steels. Results show that the presence of Sn in the low alloy steel positively affects corrosion resistance, resulting in the formation of a denser and more protective rust layer. The corrosion big data technology is a precise and intuitive approach for identifying the subtle impact of Sn on the corrosion resistance of low alloys. These findings offer insights into the mechanisms behind the corrosion resistance of low alloy steels in rural atmospheric environments and highlight the potential of Sn as an effective alloying element for improving the corrosion resistance of such structural materials.

Effects of Rare Earth Elements on Microstructure and Corrosion Resistance of Low Alloy Steel Based on Ultra-Thin Cast Strip Process

This laboratory study aimed to reveal the inner connects between the microstructure and corrosion properties of a RE microalloyed ultra-thin cast strip (UCS) steel. The microstructure mainly consisted of homogeneous polygonal ferrite (PF) with a small amount of pearlite (P), while adding multiple alloying elements led to the appearance of granular bainite (GB) and bainitic ferrite (BF). RE elements strongly promoted the homogenization and refinement of microstructure by segregating towards the solid–liquid interface. Potentiodynamic polarization, EIS, and weight loss curves under wet–dry immersion test confirmed that the corrosion behavior was significantly improved by RE, while the addition of RE had no obvious change on tensile strength. The corrosion resistance of the homogeneous single-phase microstructure was proved to be better than that of multiphase microstructure. Hence, RE had a remarkable influence on improving corrosion resistance when the experimental steels processed single-phase microstructures.

Understanding the role of alloyed Ni and Cu on improving corrosion resistance of low alloy steel in the simulated Beishan groundwater

• The addition of Ni and Cu elements significantly inhibited the cathodic and anodic processes of steel corrosion. • Ni and Cu alloy elements were obviously enriched in the inner rust layer, which could improve the compactness of rust layer. • Fe 6 (OH) 12 SO 4 stably existed in the corrosion products of NiCu steel because Ni(Ⅱ) or Cu(Ⅱ) could substitute Fe(Ⅱ) of Fe 6 (OH) 12 SO 4 and increase its oxidation resistance. • Ni and Cu made Fe3O4 ionic selective by doping, which could repel the aggressive anions and improve the corrosion resistance. The corrosion behavior of NiCu low alloy steel and Q235 low carbon steel as the candidate materials for geological disposal containers of high-level radioactive waste in the simulated Beishan groundwater was comparatively studied by weight loss test, electrochemical measurements, scanning electron microscope (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). The electrochemical results showed that the corrosion potential of NiCu steel and Q235 steel gradually increased with the immersion time. Simultaneously, the cathodic process transited from hydrogen evolution reaction (HER) control to the rust reduction control, while the anodic process was always dominated by the active dissolution of iron. By comparison, both the cathodic resistance and the anodic dissolution resistance of NiCu steel corrosion were apparently higher than that of Q235 steel. The results of rust layer characterization indicated that Ni and Cu elements could be enriched in the inner rust layer of NiCu steel and the rust layer was more compact. As the main corrosion products, the content of α-FeOOH in the rust layer of NiCu steel was obviously increased more than that of Q235 steel. Fe 6 (OH) 12 SO 4 stably existed in the corrosion products of NiCu steel because Ni(II) or Cu(II) could substitute Fe(II) of Fe 6 (OH) 12 SO 4 and increased its oxidation resistance. Moreover, Ni and Cu could also make Fe 3 O 4 ionic selective by doping. After the long-term immersion, the corrosion mass loss of NiCu steel was significantly lower than Q235 steel, which further confirmed the benefits of Ni and Cu alloying on improving the steel corrosion resistance.

Effect of Ti Addition on the Wear Resistance of Low Alloy Steel

Effect of Ti Addition on the Wear Resistance of Low Alloy Steel

Inhibition of galvanic corrosion between crystallographic orientations in low alloy steel by grain ultra-refinement

Grain refinement is an effective strategy to improve the mechanical properties of metallic materials, while the effect of grain refinement on corrosion performance is still unclear and should be widely concerned. Herein, the corrosion behaviors of ultrafine-grained steel with an average grain size of 0.6 µm prepared by cold-rolling followed by heat treatment were investigated. Ultrafine-grained steel shows lower current density (8.1 μA·cm−2), higher charge transfer resistance (1813 Ω·cm2), and polarization resistance (2542 Ω·cm2) than coarse-grained steel with the current density of 18.1 μA·cm−2, the charge transfer resistance of 1276 Ω·cm2, and the polarization resistance of 1288 Ω·cm2. The details of corrosion morphology indicated that coarse-grained steel underwent severe intra-granular corrosion, and the height difference between corroded grain and uncorroded grain is about 1.0 µm. The corrosion susceptibility of different grain orientation increases in the order {001} > {111} > {101}, and the potential difference along the {101}→{001}, {111}→{001}, and {101}→{111} is ca. 65, 55 and 10 mV, respectively. Results identified that the grain ultra-refinement can improve the corrosion resistance of low alloy steel and prevent galvanic corrosion between grains with different crystallographic orientations. The work explained the influence of grain refinement on corrosion behavior in detail and clarified the relevant contradiction reported in the existing literature.

The influence of Ni on the microstructure and corrosion resistance of high-strength low alloy steel in the Cl-containing environment

PurposeThis paper aims to search the optimum content of Ni on the microstructure, phase and electrochemical behavior of high-strength low alloy (HSLA) steel in the 3.5 wt.% NaCl solution.Design/methodology/approachThe microstructure and corrosion resistance of Ni-containing HSLA steel in the simulated marine environment was studied by optical microscopy, scanning electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques.FindingsThe sample containing 3.55 wt.% of nickel exhibited a finer grain size of 10 μm and a lower icorr of 2.169 µA cm−2. The XRD patterns showed that the Fe-Cr-Ni solid solution, FeC and Cr3C2 were observed in samples when Ni was added. Besides, the 3.55 wt.% of nickel addition enhanced the charge transfer resistance of the low alloy steel which suggested the sample possessed excellent inhibition of electrochemical reaction and corrosion resistance. The XPS spectrum suggested that nickel was beneficial to improve the corrosion resistance of steel by forming protective oxides, and the ratio of Fe2+/Fe3+ in protective oxides was increased.Practical implicationsFinding the comprehensive performance of HSLA steel which can be applied to unmanned surface vehicles in marine operations.Originality/valueThis study has a guiding significance for optimizing the composition of HSLA steel in a Cl- containing environment.

Effect of austenitic stainless steel cladding on the high-temperature oxidation resistance of Ferritic 2.25Cr-1Mo (Grade 22) steel using SMAW process

The high-temperature oxidation resistance of low alloy steel affected by the cladding of austenitic stainless steel has been investigated in this study. For this purpose, Shielded Metal Arc Welding (SMAW) technique was used to prepare a proper layer of AISI347 on the surface of ferritic steels. The microstructure and morphology properties of the alloys were examined using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX) techniques. Results demonstrated that the construction of oxide shells on the surface of non-modified ferritic steel was responsible for its low resistance in contrast to the oxidation at high-temperature conditions. The oxidation screening of coated and uncoated samples with tuning time at constant temperature showed the increased oxidizing intensity of both materials. Conversely, with tuning temperature from 850 to 950 oC at a constant time, an abnormal increase was observed in oxidation intensity. The corresponding kPs of the uncoated sample was determinate 1.27708×10-8, 3.267×10-8, and the corresponding kPs of coated material was determinate 54.5×10-10, 6.6×10-10. The performed investigation proved that the formation of oxidized compact needle microstructures in the resulting alloy is the reason for the extraordinarily oxidizing resistance of austenitic stainless steel.

Investigation on the nickel content design and the corrosion resistance of low alloy steel welded joint in tropical marine atmosphere environment

AbstractIn this study, three kinds of welding materials (WMs) with different Ni contents were designed for low alloy steel welded joints made by CO2 gas‐shielded welding technique. The corrosion resistance of welded joint was studied through the atmosphere exposure test in Trat, Thailand. Results show that there was a hardening in the heat‐affected zone after welding, and the average hardness slightly increased with the increase of Ni in WM. The electrochemical activity at the fusion line zone enhanced with the addition of Ni in WM, indicating a more obvious local galvanic corrosion effect there. Ni promoted the generation of NiFe2O4 and the transformation from γ‐FeOOH to α‐FeOOH, which increased the impedance modulus of the rust film on WM. More important, the corrosion performance assessment illustrated that the addition of Ni in WM hardly had an effect on the corrosion step values after half a year test, which confirmed that there is no need to add excessive content of Ni.

Effects on corrosion resistance of low alloy steel after plasma nitriding at elevated temperature

In the present work plasma nitriding of low alloy steel at elevated temperature for different exposure time have been performed. With the view to enhance both the hardness and corrosion resistance of the steel plasma nitriding was performed at 500 °C for 8 and 10 h. Post nitrided steel contain Fe4N and ε-Fe2–3N phases as revealed by X-ray diffraction studies. A selected set of plasma nitided samples were exposed to potentiodynamic polarization in 3.5% NaCl electrolyte for the assessment of corrosion resistance property. It was found that the nitrided steel samples possess corrosion resistance much better than the one without nitriding.

Data mining to effect of key alloying elements on corrosion resistance of low alloy steels in Sanya seawater environmentAlloying Elements

In this paper, the relationship model between seawater environment, chemical composition and corrosion potential of low alloy steel is established and the distribution of corrosion potential of low alloy steel with changes in key alloying elements is excavated. The research was carried out with the following steps: Firstly, the relationship model between corrosion potential of low alloy steel and its influencing factors was established by data dimension reduction and artificial neural network (ANN). Secondly, key alloying elements of experimental steels were selected out by Pearson correlation analysis, then the corrosion resistance element model was visualized to show the effect of key alloying elements on corrosion potential of low alloy steel. Finally, corrosion potential of low alloy steel with the change of key alloying elements was classified and visualized by classification method. The mining results can reflect the validity of the proposed mining methods to a certain extent and provide an intuitive data basis for the development of high-quality and low-cost low alloy steels.

Application of the Q-n-P-Treatment for Increasing the Wear Resistance of Low-Alloy Steel with 0.75% C

We study the influence of the Q-n-P-treatment including the interrupted quenching followed by holding at 250–350°C on the microstructure, hardness, and abrasion resistance of 75KhG2C steel. It is shown that the Q-n-P-treatment leads to the formation of a structure with elevated (27.5%) content of residual austenite. The procedure treatment with quenching interrupted at 100°C followed by the holding at 250°C for 10 min increases the abrasive wear resistance of steel by 8% as compared to the fully quenched state with a much lower hardness (57 and 63 HRC, respectively).

Abrasion resistance characterization of low alloy construction steels: A comparison between three different scratch test protocols

In the present work, three different scratch tests are compared on their ability to rank the abrasion resistance of low alloy steels for industrial applications where the abrasion play a key role, e.g., in earthmoving, agricultural and mining equipment. The first test involves single pass scratching of pristine surfaces with a relatively large rigid indenter. The second test involves multi-pass scratching along a fixed track using the same large indenter. The third test involves the creation of a multi-pass scratch track using the same large indenter followed by final scratching of the abrasion track with a sharp indenter, i.e., Multi-Pass Dual Indenter (MPDI) scratch test. The three test protocols activate different abrasion mechanisms. Five low alloy construction steel grades with different strain hardening capabilities, i.e., Interstitial-free Ferritic steel (IF steel), Fully Martensitic steel (FM steel), Dual Phase steel (DP steel), Quench Partitioning steel (Q&P steel) and TWining Induced Plasticity steel (TWIP steel), are used. The results show that for both single (large) indenter scratch test protocols, the scratch depths always increase with indenter load and the failure mechanism is pure ploughing except for the IF steel due to the nature of softness. While for the dual-indenter scratch test, the scratch depth is a more complex function of the load applied during creation of the work hardened surface layer. The conventional scratch test protocols cannot well reveal micro-cracks and defect in (sub) surface and cannot well reflect the real response of strain hardening of steels. However, the MPDI test can distinguish between different steels with different initial hardness and different strain hardening behaviour and reveal the damage and, equally important, can indicate how average loading conditions may affect the relative abrasion resistance of construction steels during steady state conditions.

Influence of chromium on the flow-accelerated corrosion behavior of low alloy steels in 3.5% NaCl solution

The corrosion behavior of carbon steel and Cr-containing steels was investigated during flow-accelerated corrosion. The corresponding weight loss and electrochemical properties were determined by using a flow-loop apparatus and a rotating-cylinder apparatus, respectively. The corrosion rate of the Cr-containing steels is lower than that of the carbon steel. Furthermore, the high corrosion resistance of these steels was closely correlated with the properties of the rust layer formed on the steel surface. Cr leads mainly to inhibition of the cathodic reaction. Therefore, Cr is suitable for improving the corrosion resistance of low alloy steel to flow-accelerated corrosion.

Increase in Corrosion Resistance in Aqueous Media of Low-Alloy Steel Used as the Main Layer of Corrosion-Resistant Bimetals

The article is devoted to a study of corrosion resistance of low-alloy steels, in relation to chemical composition, heat treatment conditions, other steel properties, and heat treatment regimes. The effect of chemical composition, degree of deoxidation, and steel cleanliness with respect to nonmetallic inclusions on steel corrosion resistance is demonstrated, including those that may be used as a main layer in corrosion-resistant bimetals.