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The effects of rare earth elements (REEs) on the corrosion behavior of weathering steels under a simulated immersion environment and a real atmospheric environment have been investigated in this paper. Although the corrosion rate of the indoor accelerated corrosion experiment (0.01 mol/L NaHSO3) is much higher than that of the real atmospheric exposure experiment, the addition of REEs can highly improve the corrosion resistance of test steels under both conditions. The improvement of the corrosion resistance can be attributed to the quick transformation of γ‐FeOOH into α‐FeOOH and the accelerated formation of a stable rust layer by REEs. Furthermore, the segregation of the REE inner rust layer increases the density of the rust layer and prevents corrosive particles from eroding the matrix. REEs can also promote the segregation of Cu, Cr, and other alloying elements in the rust layer, thus blocking the cracks and holes and enabling the formation of a continuous rust layer with good adhesion. [ABSTRACT FROM AUTHOR]

The increasing use of weathering steels (WS) has raised concerns regarding the diffuse emission of alloying elements. This research paper investigates the release of iron (Fe) and the alloying elements (Cr), copper (Cu), manganese (Mn) and nickel (Ni) from two commercially available WS at urban field conditions in Stockholm, Sweden, during 1 year and in the laboratory at simulated urban conditions. The amount of released metals is evaluated and compared with recommended levels of metals in drinking water and the formation and evolution of the protective patina is studied in parallel to assess the influence on the metal release process. Only minor amounts of the alloying elements are released and is only linked to the outermost surface composition of the patina during the very beginning of the exposure. The released amounts are found to be lower compared with the corresponding levels recommended by the World Health Organisation for drinking water. [ABSTRACT FROM AUTHOR]

Shui Su Ravine Bridge is built in Bai Shui County in Shaanxi Province, which is a part of the highway linking Heyang and Tongchuan. The bridge has been designed as a composite steel‐concrete truss bridge with 3 spans in total of 240 meters and a deck of 4 lanes. To meet the harsh environmental demand and lessen the future maintenance, the solution adopts the weathering steel Q420qENH similar strength as S420NL in European code. The bridge is erected by incremental launching and post‐installation of the pre‐cast concrete slab. Since the truss segment is all welded, two‐step models have been developed to evaluate the fatigue performance of the steel truss joint. In the simplified two‐dimensional model, Phase‐Field (PF) approach has been implemented to make a full fatigue evaluation of crack propagation in the truss. [ABSTRACT FROM AUTHOR]

Responsible for 70% of the global CO2 emissions, infrastructure has a significant impact on our climate and the related consequences. Bridges are a major keystone of the infrastructure and take a leading position in its decarbonization. In this framework, low‐carbon emission steels play an important role. Low‐carbon emission steels, like ArcelorMittal's XCarb® recycled and renewably produced steels, are already available on the market. Combining scrap and renewable electricity, it offers very low levels of CO2 emissions per ton of finished steel. The present paper describes how different steel solutions can be combined to lower the material input, to simplify the construction process and to reduce the maintenance efforts in bridge construction. The impact of efficient design has been assessed by a Life‐Cycle Assessment (LCA) for bridge solutions with small and medium spans of up to 40 m. The paper concludes with a summary of recently realized bridge projects in Poland. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a high-strength low carbon Nb–Ti containing weathering steel was developed. The steel achieved a yield strength of 824.4 MPa and an elongation of 24.4% with the addition of 0.030% Ce as a microalloying element. Precipitation strengthening and dislocation strengthening contributed nearly 60% to the yield strength of the steel. The effects of Ce on the dissolution and precipitation behavior of microalloying elements were analyzed through experimental research and first-principles calculations. Additionally, the associated strengthening mechanisms were elucidated. The findings revealed that the Ce–Nb pairs within the 2 to 7 nearest-neighbor configuration in face-centered cubic Fe exhibited a mutual attraction. This attraction promoted the dissolution of microalloyed carbonitrides, leading to a reduction in the volume fraction of precipitates with diameters above 150 nm from 1.3% to 0.62%. Conversely, in the body-centered cubic Fe structure, Ce–Nb atom pairs were mutually repulsive across all configurations. During the coiling process, the addition of Ce increased the formation of nanoprecipitates in the 0.030% Ce–Nb–Ti weathering steel. Particularly, the volume fraction of precipitates with diameters ranging from 20 to 150 nm in the steel increased from 1.6% to 2.7%, while the fraction of nanoprecipitates also increased from 0.051% to 0.31%. The nanoprecipitates formed within the dislocation substructure of the ferrite significantly enhanced steel strength but reduced its plasticity. Additionally, the addition of Ce led to the formation of numerous fine cementite particles in the localized areas of the steel matrix, which contributed up to 49.2 MPa to the overall strength of the steel.

The corrosion behaviors of two bridge steels (Q345q and Q500q) under simulated ultraviolet irradiation and a wet–dry alternating (UVWD) environment were studied. Weight loss measurement, stereomicroscope observation, SEM, XRD, and electrochemical impedance spectroscopy (EIS) were performed to investigate the influence of the coupled environment. The results revealed that the corrosion rates of Q345q and Q500q were significantly accelerated by the synergistic effect of UV light exposure and alternating wet–dry conditions. Numerous voids and cracks could be observed throughout the thickened rust layers, enabling the corrosive substances to easily penetrate through the rust layer. Q500q exhibited better corrosion resistance than Q345q due to the addition of Mo, Cr, and Ni as corrosion-resistant elements, which tended to transform the rust layer into α-FeOOH rather than γ-FeOOH during later stages of corrosion. [ABSTRACT FROM AUTHOR]

The corrosion behavior of Q345qNH steel and Q420qNH steel in simulated industrial atmospheric environment medium was studied by periodic immersion+infrared aging corrosion experiment. The results show that the corrosion type of both samples is uneven comprehensive corrosion, and the rust layer formed in the later stage of corrosion is relatively dense. But average corrosion rate of Q345qNH steel is always lower than that of Q420qNH steel, and the ratio of Iα‐FeOOH/Iγ‐FeOOH in rust layer is always higher. Compared with Q420qNH steel, Q345qNH steel has fewer surface pits but deeper local pits. The self‐corrosion potential of Q345qNH steel increases obviously, the resistance of the rust layer is larger, and protection to the matrix is stronger. This is because the formation of a large number of corrosion microcells induced by fine lamellar sorbite tissue that uneven distributed in Q420qNH steel, which increases the corrosion rate and makes corrosion uneven, while the larger pearlitic group in Q345qNH steel increases the local corrosion rate. However, the higher chromium/carbon ratio in Q345qNH steel promotes the conversion of lepidocrocite to goethite and inhibits the cathode reaction in the infrared drying stage, improving the density and stability of the rust layer. [ABSTRACT FROM AUTHOR]

The corrosion behaviors of three bridge steels in a real tropical marine environment for 2 years were studied. One weathering steel (WS) was designed with higher levels of nickel, copper, and molybdenum compared to the other. These two kinds of WSs and one kind of ordinary high-strength low-alloy steel (Q345qe) were compared under two conditions (marine atmospheric zone and marine immersion zone at Sanya Marine Environmental Test Station). The morphology, corrosion rate, and corrosion product analysis of the steels were performed through SEM, XPS, FTIR and other characterization methods. The results demonstrated that weathering steels facilitate the densification of the corrosion product layer due to the addition of alloying elements Cr, Ni, and Cu, promoting rust nucleation and enhancing the compactness of the protective layer. However, in an immersion environment, the extensive erosion by chloride ions renders the benefits of WS ineffective. [ABSTRACT FROM AUTHOR]

Weathering steel (WS) and high‐performance steel (HPS) have been widely used in bridge engineering. Investigating the corrosion performances of WS and HPS is of great significance to the safety evaluation and maintenance of uncoated WS or HPS bridges, especially aging bridges. This study focused on the correlation between the corrosion performance and composition of the rust layer. Accelerated corrosion tests were conducted on Q345CNH and HPS 70 W to observe their corrosion performance under salt‐spray corrosive environment. Based on the results of corrosion test and the existing corrosion attack evaluation theories, the empirical formulae of uniform corrosion and pitting corrosion were derived. X‐ray diffraction experiments were performed to analyze the composition of the rust layer formed on the surface of steel specimens after various corrosion cycles. The relationship between the composition of the rust layer and the corrosion performance was established. The test corrosive environment was verified to be consistent with the C3 environment. The conclusions of this study could provide guidance for the corrosion evaluation in the following test or practical application. [ABSTRACT FROM AUTHOR]

Traditional 3Ni weathering steel cannot completely meet the requirements for offshore engineering development, resulting in the design of novel 3Ni steel with the addition of microalloy elements such as Mn or Nb for strength enhancement becoming a trend. The stress-assisted corrosion behavior of a novel designed high-strength 3Ni steel was investigated in the current study using the corrosion big data method. The information on the corrosion process was recorded using the galvanic corrosion current monitoring method. The gradient boosting decision tree (GBDT) machine learning method was used to mine the corrosion mechanism, and the importance of the structure factor was investigated. Field exposure tests were conducted to verify the calculated results using the GBDT method. Results indicated that the GBDT method can be effectively used to study the influence of structural factors on the corrosion process of 3Ni steel. Different mechanisms for the addition of Mn and Cu to the stress-assisted corrosion of 3Ni steel suggested that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel during the early stage of corrosion. When the corrosion reached a stable state, the increase in Mn element content increased the corrosion rate of 3Ni steel, while Cu reduced this rate. In the presence of stress, the increase in Mn element content and Cu addition can inhibit the corrosion process. The corrosion law of outdoor-exposed 3Ni steel is consistent with the law based on corrosion big data technology, verifying the reliability of the big data evaluation method and data prediction model selection. [ABSTRACT FROM AUTHOR]

This study discusses the comparative weatherability of three microstructures of ferrite, ferrite + bainite, and bainite, obtained by controlling the rolling and cooling processes of a well-established weathering steel by adding 3 wt% Ni in tropical marine atmospheric environments. In field exposure in the Trat (Thailand) and accelerated laboratory testing, the bainitic steel showed superior weathering resistance compared to the other microstructures. The corrosion rates after 12-month of exposure were 0.012 mm/y for ferritic steel, 0.010 mm/y for ferritic + bainite steel, and 0.009 mm/y for bainitic steel. An analysis of the electrochemical properties of the rust layer, its phase composition, and morphological observations revealed that the influence of microstructure on the atmospheric corrosion rate of weathering steels primarily depend on the density of the rust and the adhesion between the rust layer and the substrate. [ABSTRACT FROM AUTHOR]

The effect of coupling of copper and phosphorus in steel on atmospheric corrosion behavior was investigated using high-throughput experimental methods. Wire beam electrodes and plates with discrete distribution of composition gradients were prepared through a selective laser melting method. By combining array electrode scanning tests and EPMA, the electrochemical properties and the relationship between different copper and phosphorus contents were rapidly determined. Plenty of data obtained were analyzed according to relevant standards and screened to identify compositional ranges corresponding with the relevant compositions of existing grades of steel. To further analyze the effect of copper and phosphorus on the corrosion behavior, dry/wet cyclic corrosion test were performed using plates. A combination of XRD, FTIR, SEM, EDS, and EPMA were used to analyze the corrosion behavior. It was observed that both copper and phosphorus promoted the formation of amorphous substances, supporting the proposed mechanism by previous researchers. Furthermore, in the absence of manganese interference, copper could accumulate at the metal/rust layer interface, rendering the rust layer cation-selective and effectively inhibiting the deep penetration of chloride ions. Moving forward, we expect to develop this high-throughput experiments to investigate the coupling effects of other elements on corrosion behavior.

To explore the influence of oxygen content on the corrosion resistance of steels, carbon and weathering steels with different oxygen contents of (20×10−6–200×10−6) were smelted. Using scanning electron microscopy inclusion analysis, polarization curve test, and full immersion test, the change rules of inclusion type, shape, quantity, size, and corrosion resistance under different corrosion environments with changing oxygen content in steel were investigated. The findings indicated that with increasing oxygen content in the steel, the inclusions in the steel changed from long strip MnS and Al2O3 to granular silicate inclusions, and the total number and mean size of all inclusions increased gradually; for instance, with the oxygen content increasing from 20 × 10−6 to 60 × 10−6 and then to 195 × 10−6, the number fraction of MnS decreased from 69.9% to 23.7% and then to 5.8%, the number fraction of silicate increased from 3.4% to 54.9% and then to 73.2%, the total area fraction of inclusions increased from 0.01% to 0.04% and then to 0.25%, and the equivalent circle diameter (ECD) increased from 0.78 µm to 1.15 µm and then to 4.65 µm, respectively. The pitting potential demonstrated a positive tendency, with an overall increase of about 40 mV. The full immersion corrosion rate first decreased and then increased, following the cubic function change rule. When the oxygen content increased from (20×10−6–30× 10−6) to 60 × 10−6, the corrosion rate of carbon and weathering steel decreased by 53% and 24%, respectively. The corrosion resistances of carbon and weathering steels were enhanced, and the corrosion rate of weathering steel was evidently lower than that of carbon steel, which is below 3 mm·a−1. With the corrosion time prolonging from 24 h to 48 h and then to 96 h, the corrosion rates of carbon and weathering steels decreased significantly, and the corrosion gradually slowed down. From the analysis, there were mainly long strip sulfides in the steel with an oxygen content of (20×10−6–30×10−6). When the steel plate experienced pitting corrosion, the sulfides exposed on the pit wall rapidly dissolved, speeding up the corrosion process. The long strip sulfides were reduced in the steel at an oxygen content of (60×10−6–85×10−6), and most of them were replaced by silicate composite inclusions that did not easily induce pitting corrosion, and the corrosion propagation was restrained, which is demonstrated by good corrosion resistance. At an oxygen content of 195 × 10−6, the average ECD of inclusions in the steel and the total area fraction of inclusions was four times and six times that of the steel with an oxygen content of 60 × 10−6, respectively. This large number of inclusions as the source of pitting corrosion leads to the steel matrix being vulnerable to severe corrosion, which is characterized by poor corrosion resistance. Thus, at an oxygen content of (20×10−6–100 × 10−6), the corrosion resistance of steel in the full immersion corrosion environment was improved due to the combined effect of the reduction of long strip sulfide that can easily induce corrosion and the increase in solid solution oxygen to increase the matrix potential. At an oxygen content of (100×10−6–200 × 10−6), the corrosion resistance of the steel was weakened due to the sharp increase of inclusions. Therefore, economical corrosion-resistant steel can be developed by increasing the oxygen content appropriately.

In this paper, Sb and Sn elements were added to high-strength weathering steel. The corrosion behavior of three kinds of high-strength weathering steels without Sb/Sn, with Sb and Sb + Sn in a simulated industrial atmosphere, was studied. The results show that adding Sb and Sn can accelerate the initial corrosion rate, quickly form a more dense and stable rust layer, and thus reduce the corrosion rate and total corrosion amount in the later period. Sb and Sn are uniformly distributed in the rust layer and play an important role in improving the density of the rust layer. The corrosion resistance of weathering steel is improved after the addition of Sb alone and Sb + Sn combined, and the corrosion resistance is more excellent when the composite is added. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the corrosion resistance of weathering steels (WS) with five different Mo/Ni ratios (blank, 1:2, 1:1, 3:1, and 5:1) in a simulated tropical marine atmosphere. The results revealed that the synergistic effect between Mo and Ni with a 3:1 ratio led to the optimal atmospheric corrosion resistance of WS. Reducing Ni promotes the growth of nano-structured Fe(O,OH)6, while increasing Mo disrupts the structure of Fe(O,OH)6, creating additional nucleation sites for corrosion products. The evolution of the rust layer is governed by the growth of Fe(O,OH)6 at low Mo/Ni ratios, while the destruction of Fe(O,OH)6 by Mo becomes dominant as the Mo/Ni ratio increases. The optimized ratios (3:1) contain more α-FeOOH in the rust layer, compact the rust layer, reduce defects, and inhibit the charge transfer processes, thereby attaining better atmospheric corrosion resistance of WS. [ABSTRACT FROM AUTHOR]

In this paper, the corrosion environment of a railway coal truck was simulated with 1.0%H2SO4 + 3%NaCl solution. The effect of weld toe Tungsten Inert Gas (TIG) remelting on the microstructure and corrosion resistance of welded joints of Q450NQR1 high-strength weathering steel was studied. The results show that the weld toe melts to form a remelting area after TIG remelting. After TIG remelting, the weld geometry was improved, and the stress concentration factor decreased from 1.17 to 1.06 at the weld toe, a decrease of 9.4%. TIG remelting refines the microstructure of the weld toe and improves the corrosion resistance of the welded joint. The surface of the TIG-remelted sample is uniformly corroded with no "deep and narrow" pits after the removal of corrosion products. The weight loss rate and corrosion rate of remelted welds are lower than those of unremelted welds. The structure of corrosion products is loose at the initial stage of corrosion, and the corrosion products are transformed into Fe3O4 and Fe2O3 protective rust layers with a dense structure after 480 h of corrosion. With the extension of corrosion time, the tensile strength and percentage elongation of the specimen decreased linearly. The decreasing rates of tensile strength of remelted and unremelted specimens were 0.09 and 0.11, respectively, and the decreasing rates of elongation after fracture were 0.0061 and 0.0076, respectively. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to study the effect of ultraviolet (UV) light on the corrosion behavior of BC550 weathering steel in simulated marine atmospheric environment. Design/methodology/approach: The effect of UV light on the corrosion behavior of BC550 weathering steel in simulated marine atmospheric environments were investigated by the corrosion weight gain experiment, in situ electrochemical noise, scanning electron microscope and X-ray diffraction. Findings: UV light accelerated the corrosion process of BC550 weathering steel in the simulated marine atmospheric environment during the first 168 h. The maximum influence factor of UV light was 0.32, and it was only 0.08 after 168 h of corrosion process. Originality/value: As the extension of corrosion time, the thickness and density of the corrosion product layer increased, which weakened the acceleration effect of UV light. [ABSTRACT FROM AUTHOR]

The paper studies the influence of arc welding technological processes on the resistance of welded joints of sparcely-alloyed weathering 06g2BDP steel to cold and hot cracking and brittle and fatigue fracture. with the help of the Implant method and using the technological tekken sample, the conditions for cold cracking were evaluated and the methods of their elimination were recommended. It is shown that with the use of mechanized welding in shielding gases, solid-section and flux-cored wires provide high technological strength of welded joints in terms of hot cracking in a wide range of welding modes. On the other hand, when using coated electrodes, this range is narrowed, and at Vdef ≥ 20 mm/min, joints are prone to the formation of this defect. the results of studies on the evaluation of welded joint resistance to brittle fracture indicate high values of the stress intensity factor KQ for both the weld and HAZ metal. The endurance limit of T-joints when tested by cyclic loading was determined, which is [σ]-1 = 35 MPa. [ABSTRACT FROM AUTHOR]

The effects of rare earth (RE) elements on inclusions and impact toughness of a weathering steel (Q355NHBRE) were studied in this paper. The microstructures, inclusions and impact fractures were observed by optical microscopy, scanning electron microscopy and auger electron spectroscopy. The results showed that the addition of RE elements increased the content of pearlite and modified elongated MnS and irregularly shaped composite inclusions into fine spherical RE inclusions. The segregation of RE elements towards grain boundaries reduced the segregation of impurity elements (P, S), thus purifying grain boundaries and improving grain boundary binding force. After RE alloying, Q355NHBRE steel had greater upper shelf energy and lower ductile–brittle transition temperature, which improved the low temperature impact toughness. [ABSTRACT FROM AUTHOR]

Weathering steel has recently become popular in engineering due to its corrosion resistance, but its mechanical characteristics must alter during double corrosion, process chemical solution corrosion (CSC), and atmospheric corrosion (AC). However, no studies have been published on the coupling effect of process and atmospheric corrosion. The durability and safety of weathering steel structures can be challenging to assess. As a result, we used SPA-H weathering steel as the object, ran process corrosion and double corrosion simulations (process corrosion plus atmospheric corrosion simulation), and created three corrosion conditions: non-corrosion, single-side corrosion, and double-side corrosion. CSC was the corrosion process. Following CSC, the second (120, 360, 720, and 1200 hour) Copper-Accelerated Acetic Acid-Salt Spray Testing (CASS) was performed to simulate atmospheric corrosion. A correlation analysis was conducted using the grey correlation method between indoor and atmospheric corrosion. After corrosion testing, these specimens were subjected to White Light Interferometry (WLI) and tensile coupon tests (TCT) to evaluate the corrosion characteristics and the deterioration of material mechanical properties. Finally, linear fitting was used to produce the calculation formula between the mechanical properties and the mass loss ratio of single-side and double-side corrosion.

One significant form of deterioration in weathering steel bridges is corrosion, and steel requires water and oxygen to corrode. As a measurement method for the wetness time of the rust layer on weathering steel, measuring electrical resistance has been proposed. In this research, the fundamental data have been collected as preliminary considerations to develop this method of measuring water retention in the rust layer. Based on the measurement of specimens, it is revealed that measuring the exact amount of water retention is difficult because electrical resistance depends on the thickness of the rust layer and the supplied amount of NaCl. Thus, the water retention ratio is calculated by dividing the mass of the water-retained specimen by the mass of the full water-retained specimen. These measurement results suggest a potential method for predicting water retention ratio by measuring electrical resistance and rust thickness. The approximate water retention ratio is predicted by plotting electrical resistance and rust thickness in the proposed diagram. [ABSTRACT FROM AUTHOR]

This study investigates the role of Si on the corrosion resistance of weathering steel (WS) in a simulated industrial environment. With increasing Si content (0.15–0.50%), the corrosion resistance of WS is enhanced. On the one hand, the rust layer becomes compact and uniform because higher Si content promotes the formation of fine α-FeOOH. On the other hand, Si reacts with Fe3O4 to form a three-dimensional SiO2 network structure located around the cracks and holes of the rust layer. This structure has a protective effect, enhancing the corrosion resistance of WS and equipping the rust layer with self-healing functionality.

The corrosion behaviors of three bridge steels in a real tropical marine environment for 2 years were studied. One weathering steel (WS) was designed with higher levels of nickel, copper, and molybdenum compared to the other. These two kinds of WSs and one kind of ordinary high-strength low-alloy steel (Q345qe) were compared under two conditions (marine atmospheric zone and marine immersion zone at Sanya Marine Environmental Test Station). The morphology, corrosion rate, and corrosion product analysis of the steels were performed through SEM, XPS, FTIR and other characterization methods. The results demonstrated that weathering steels facilitate the densification of the corrosion product layer due to the addition of alloying elements Cr, Ni, and Cu, promoting rust nucleation and enhancing the compactness of the protective layer. However, in an immersion environment, the extensive erosion by chloride ions renders the benefits of WS ineffective.

In order to investigate the corrosion resistance of reinforced gabion rebars in dry and wet cyclic salt environments，the failure behavior of HPB300 ordinary steel，NH400 weathering steel，NS142 and NS336 corrosion resistance steels in a dry and wet cyclic salt spray [5%(mass fraction) NaCl solution] corrosion environment was studied by dry and wet cyclic accelerated corrosion test.The changes in corrosion rate，phase，morphological structure and electrochemical properties of 4 types of steels in a dry wet cyclic salt solution medium were studied by corrosion weight loss method，XRD，SEM and electrochemical test，and the changes in corrosion resistance and mechanical properties of 4 types of steel in simulated accelerated environment were further compared and analyzed.Results showed that after 105 cycles of accelerated cycling in 5%NaCl solution corrosion medium，the corrosion rates of HPB300 steel and NH400 steel were significantly higher than that of NS142 and NS336，and the self-corrosion potential was more negative.After accelerated corrosion test，the tensile strength of HPB300 steel could no longer meet the application requirements of reinforced gabion rebars，whereas the tensile strength of NH400，NS142 and NS336 still met the service conditions.Therefore，NS142 and NS336 corrosion resistant steel were more suitable for the application of reinforced gabion rebars in salt spray corrosion environment.

This study investigated the effect of heat inputs on coarse-grained heat affected zone (CGHAZ) microstructure and impact properties of a novel vanadium (V) and nitrogen (N) microalloyed weathering steel via a Gleeble™ system, revealing the metallurgical essence of the steel suitable for large heat input (Ej) welding. The results indicate that in CGHAZ, the dominant microstructure was composed of lath bainitic ferrite (LBF) at Ej = 15 kJ/cm, granular bainitic ferrite (GBF) at Ej = 35 kJ/cm, and a mixture of intragranular acicular ferrite (IGAF), intragranular polygon ferrite (IGPF) and grain boundary polygonal ferrite (GBPF) at Ej = 55 and 75 kJ/cm, respectively, apart from martensite/austenite (M/A) constituents in each one. The area fraction, fM/A, and mean size, dM/A, of M/A constituents increased monotonously with the Ej. In addition, with increasing Ej from 15 to 35 kJ/cm, the fraction, fMTAs＞15°, of high-angle grain boundaries (HAGBs) with misorientation tolerance angles (MTAs) greater than 15° reduced, while the mean equivalent diameter, MEDMTA≥15°, of grains with HAGBs increased. However, as Ej further increased to 55 and 75 kJ/cm as the two large heat inputs, the precipitation of (Ti, V) (C, N) and thereby the heterogeneous nucleation of polygonal and acicular ferrite were promoted by a lowered degree of undercooling, resulting in the decreased MEDMTA≥15° and the increased fraction fMTAs＞15°. Accordingly, the impact toughness of CGHAZ was degraded with the increase of Ej from 15 to 35 kJ/cm, but enhanced with the increase of Ej from 35 to 75 kJ/cm.

To accelerate the formation of the protective rust layer on weathering steel, a new pre-corrosion method containing a replacement reaction was explored. This process was mixed with Cu in the pre-corrosion rust layer to imitate the enrichment of alloying elements through long-term corrosion. By using various analysis methods, the initial corrosion behavior of weathering steel and carbon steel with/without pre-corrosion treatment was studied under indoor wet-dry cycle conditions. The results showed that the pre-corrosion treatment covers the steel surface with a rust layer containing high-concentration Cu. Subsequently, the corrosion uniformity of the weathering steel was significantly improved, and the protective performance of corrosion products was enhanced due to the high concentration of Cu enrichment. This technology is expected to provide a new way to perfect the service performance of weathering steel at the initial stage of application.

In this study, the effect of finish rolling temperature on the critical crack tip opening displacement (CTOD) of typical 500 MPa grade weathering steel was elucidated. The microstructures were observed via optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and electron back-scattered diffraction (EBSD). The cryogenic fracture toughness and microstructures of steels were analyzed at different finish rolling temperatures (780–840 °C). The results show that a mixed microstructure, i.e., granular bainitic ferrite (GBF), polygonal ferrite (PF), and martensite/austenite (M/A), constituent was formed in each sample. With the decrease of the finish rolling temperature, the GBF content decreased, PF content increased, and the high angle grain boundary (HAGB) number fraction of the matrix increased. Furthermore, the fraction of M/A constituents was increased with reduced average size. The value of CTOD increased significantly from 0.28 to 1.12 mm as the finish rolling temperature decreased from 840 to 780 °C. Both the decrease of M/A constituents and the increase of HAGB increased the cryogenic (−40 °C) fracture toughness of the typical 500 MPa grade weathering steel. [ABSTRACT FROM AUTHOR]

The structure of 531.4 m total length bridge was made in early nineties last century and it was regarded as novelty by that time. The interesting point was that the structure was made of original Polish weathering steel prepared for bridge solutions intently. There were several trouble concerning the bridge service, steel cracks and less than expected patina growth due to the unfavorable conditions inside the box girder. Quite recently the bridge was carefully inspected as it was to be an important issue of the modern motorway. There was a question if the bridge is to be demolished, due to the corrosion and structural problems or to be preserved and extended to meet required traffic volume. There was a careful examination performed including metallurgical, corrosion and structural analysis done. The paper is to present the most important outcomes concerning mainly structural issues, but some weathering steel corrosion observation will be provided as well. [ABSTRACT FROM AUTHOR]

This study examined the spatial characteristics of the corroded surface of weathering steel by different environmental conditions to evaluate the applicability of two accelerated corrosion tests. Two types of weathering steel were subjected to the two accelerated corrosion tests for 28, 84, and 168 days. The same materials were also exposed at two separate locations for 180 and 365 days of atmospheric exposure tests. The corrosion behavior of the weathering steel was investigated by spatial statistical analysis. The analysis suggested that the spatial properties of the corrosion of weathering steel experimented in the early stage of both accelerated corrosion tests were close to those obtained in the atmospheric exposure tests. Furthermore, the corroded surfaces experimented under the ISO 16539 Method B accelerated corrosion test demonstrated a closer resemblance to the corroded surfaces of weathering steel in real corrosion environments compared to those derived from the Cyclic Corrosion Test Method A. [ABSTRACT FROM AUTHOR]

The impact of microstructure evolution on the mechanical properties of a typical 500 MPa-grade weathering steel produced by an identical thermo-mechanical control process and different tempering treatments at 450–650 °C were thoroughly investigated mainly using scanning electron microscopy (SEM) equip with an electron backscatter diffraction (EBSD), high-resolution transmission electron microscopy (HRTEM), and X-ray diffractometer (XRD). Results indicated that the as-rolled steel consists of granular bainitic ferrite (GBF) and a considerable amount of martensite/austenite (M/A) constituents, exhibiting unsatisfied mechanical properties. As the tempering temperature increased from 450 to 550 and 650 °C, the massive twin-type M/A constituents decomposed preferentially into carbides following the sequence of Fe3C→(Cr, Mn, Fe)3C→(Cr, Mn, Fe)3C + (Cr, Mn)23C6, with a small amount of fine lath-type M/A constituents remained. The matrix recovered with the bainitic ferrite laths merged, the dislocation density decreased and the proportion of high-angle grain boundary (HAGB) increased. Nanoscale (Ti, Nb)C and ε-Cu particles also precipitated simultaneously, leading to an increase of yield strength. The strain hardening capacity and hence the tensile strength reduced resulting from the decomposition of M/A constituents. Moreover, the impact toughness was first enhanced by tempering at 450–600 °C with the decreasing twin-type M/A constituents content and increasing HAGBs proportion, and then deteriorated by tempering at 650 °C due to the precipitation of necklace-like M23C6 carbides at the grain boundaries. An optimum mechanical property combination was achieved via tempering at 550–600 °C.

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Construction of the new Büchler bridge in Luxembourg The transport infrastructure project new national road N3 covers several districts of the capital city of Luxembourg and includes the replacement of the Büchler bridge, running over all twelve railroad tracks south of the main station, which is necessary in this context. The new bridge design is characterized by a significantly widened traffic cross‐section that carries a total of six lanes for road traffic and a new double‐track tram line, in addition to wider sidewalks and bike lanes. The traffic is supported by an undivided girder grid, whose three main girders in the form of steel sails pierce the carriageway slab above the inclined intermediate supports. The design of the new bridge is characterized by the small possible construction height below the roadway level, which resulted from the maintained longitudinal profile of the N3 in the construction area and the increased clearance height of 0.85 m for rail traffic under the bridge. The present report describes the challenging planning and the demanding construction work at the same location under full traffic. [ABSTRACT FROM AUTHOR]

Weathering steel is used more and more widely in various fields of production and life.A rust layer stabilization treatment on the surface of weathering steel before usage can enhance both material life extension and beautification，promoting the mutual coordination between weathering steel and its service environment.In this paper，the research status of surface stabilization treatment technique of rust layer on weathering steel was summarized，which mainly included the formation，composition，structure and protection mechanism of rust layer，especially the disadvantages of traditional technology and novel technology.Finally，the further development of the surface rust layer stabilization treatment was prospected.

In this paper, the corrosion behavior of E690 steel with different chloride concentrations was studied. Combined with the corrosion weight loss, corrosion morphology, corrosion products, electrochemical phenomenon, and the transformation process of corrosion products, the influence of different Cl− concentrations on the corrosion characteristics of E690 steel was studied. The results showed that the corrosion rate of E690 steel increased with the increase of Cl− concentration, and the corrosion rate reached the highest at 3.5% Cl− concentration, and then decreased. The corrosion morphology and electrochemical properties of E690 steel were consistent with the corrosion rate. At the initial stage of corrosion, The concentration of Cl− affected the corrosion resistance of E690 steel by affecting the reaction process of anode and cathode. When Cl− is less than 3.5%, Cl− had an anodic depolarization effect on E690 steel and accelerated anodic dissolution. When Cl− reaches 3.5%, the diffusion of oxygen was hindered, and the existence of film of Fe(OH)2 also reduced the dissolved oxygen in the film environment on the metal surface, leading to the weakening of corrosion. In addition, Cl− affects the corrosion resistance of E690 steel by affecting the transformation of corrosion products. When Cl− in solution reaches 3.5%, β-FeOOH appears in corrosion products of E690 steel. Compared with γ-FeOOH, β-FeOOH is highly reductive and can be rapidly reduced to Fe3O4, thus accelerating the corrosion reaction.

Effect of pre-tension deformation on the rusting behavior of S450EW weathering steel was studied through electrochemical measurements and characterizations on rust layer. The rust layers are no longer stratified and become porous on the deformed samples. Simultaneously, the occlusion effect beneath the rust layer is alleviated. Owing to the above both aspects, the rust layer keeps a composition of approximately 7 wt% γ-FeOOH, 20 wt% α-FeOOH, and 73 wt% Fe3O4/γ-Fe2O3 under each deformation degree. The deformation increases the defects in the incipient passive film, thereby promoting rust generation but leaving inadequate time for the evolution of the rust layer.

In this work, the corrosion behavior and corrosion mechanism of S500AW weathering steel in sulfuric acid environment were studied by the analysis methods of immersion test, corrosion weight loss analysis, macroscopic morphology analysis, SEM, XPS and electrochemical test. The results show that the corrosion rate of S500AW is significantly lower than that of Q345B. The corrosion products of both steels contain FeO, Fe2O3, Fe3O4 and FeOOH, while the corrosion product layer of S500AW also contains Cu, CuO and Sb2O3. The presence of Cu and Sb2O3 helps to improve the adhesion of corrosion produt layer to the substrate. And the corrosion product layer gradually reaches a dynamic balance during dissolution and regeneration, which prevents the invasion of corrosive ions to a certain extent. In addition, the Sb element will consume local H+ during the formation of Sb2O3, inhibiting the oxygen reduction reaction and reducing the local acidity. These reasons all make the S500AW substrate corrode in a relatively mild environment and make S500AW has a better corrosion resistance.

Starting from Germany, the VFT bridge girder technology (prefabricated composite beam) has spread in several European countries in the last decades as further development of the standard steel‐concrete composite solution. Its configuration fits perfectly to integral frame bridges built over existing infrastructure with the scope to minimize the traffic disturbance. In this paper a further development with the focus on cost efficiency in span ranges of 40‐55 m is proposed: the RS‐Overpass technology. The change consists in using standard rolled sections by adapting them into the integral frame bridge configuration, further enhancing the structural efficiency with the benefits of high‐steel strength. The constructive details to achieve the polygonal form have been studied to allow easy fabrication and a maximal clearance height over highway traffic lanes. The RS‐Overpass solution is conceived as the economic option of standard highway overpasses, with the aim of a overall construction cost reduction of 5%. The possibility of weathering steel or hot‐dip galvanization create the unique offer for a maintenance‐free solution. [ABSTRACT FROM AUTHOR]

The corrosion resistance and influence mechanism of P in low-Ni Cu-P-Cr-Ni weathering steels were analyzed by wet/dry cyclic corrosion and electrochemical tests. The electrochemical experiment results showed that the corrosion potential and impedance of weathering steels were all more positive than that of ordinary Q345B carbon steel. Compared to Cu-0.02P-Cr-Ni steel, however, the corrosion current density of Cu-0.07P-Cr-Ni steel was higher. After 72 h wet/dry cyclic corrosion tests, the corrosion resistances of the two weathering steels were nearly identical but better than that of Q345B steel. The effect of P was particularly significant in the initial stage of corrosion. Phosphates (PO43−) were formed from P, which improved the corrosion current density and promoted the rapid formation of a rust layer. After 72 h wet/dry cyclic corrosion tests, the matrix was further protected by the enrichment of Cu and Cr, which existed as Cu+ and Cr3+, respectively. The P content did not significantly affect the corrosion resistance of weathering steels after 72 h wet/dry cyclic corrosion tests. Therefore, the P content can be lowered to reduce the cold brittleness in low-Ni Cu-P-Cr-Ni weathering steels. [ABSTRACT FROM AUTHOR]

The microstructural evolution and mechanical properties of welded joints for Q450NQR1 and Q450AWR5 alloys were investigated. The inhomogeneous microstructures of Q450NQR1 and Q450AWR5 welded joints can result in heterogeneous mechanical responses. Microhardness distributions of the two welded joints are not uniform with the highest hardness value in the FZ, followed by the HAZ, and the lowest hardness value in the BM. The tensile strength of Q450AWR5 welded joints is slightly higher than the Q450NQR1 welded joints. The tensile fracture occurred in the BM of both welded joints, probably due to the strengthening effect of bainite with high dislocation density and lattice distortion. The fatigue life is dominated by the welded defects inside the welded joint. The location of fatigue failure occurs mainly near the fusion zone and is limited by the welded defects, independent of the microstructure. Highlights: Microstructure and mechanical properties of weathering steel welded joints were studied.Microhardness values of two welded joints are nonuniform and the maximum value in FZ.High dislocation density bainite strengthening contributed to failure occurring in BM.Welded defects are insensitive to tensile behavior but extremely sensitive to fatigue behavior. [ABSTRACT FROM AUTHOR]

The water treatment experiment for rust layer stabilization for Q500qENH weathering steel was carried out in seven different locations for 8 weeks to determine the applicability of the optimal treatment process. Results showed that with the prolonging of the stabilization treatment period, the weight loss and corrosion thinning of the samples increased, the corrosion rate presented a downward trend, and the color of the rust layer on the surface of the samples changed from orange to brown. In addition, the thickness of the rust layer increased gradually. The electrochemical analysis results indicated that the self - corrosion current density of the samples decreased, and the self - corrosion potential gradually shifted positively with the prolonging of the stabilization treatment period. Meanwhile, the results of XRD analysis revealed that the unstable phase (γ - FeOOH) gradually transformed into stable phase (α - FeOOH), and the proportion of stable phase (α - FeOOH) gradually increased with the extension of stabilization treatment period. To sum up the above results, Q500qENH weathering steel was treated by different rust layer stabilization water treatment processes in 3 kinds of typical locations, and a relatively stable rust layer could be obtained after 4～6 weeks.

Defect-free sound joints of high-phosphorus (0.094 wt%) weathering steel (SPA-H) were successfully fabricated using friction stir welding (FSW). This study examines the microstructural evolution and mechanical properties of joints produced at different FSW parameters. Tensile tests of the joints revealed that fractures occurred in the base metal (BM) region, indicating almost 100 % welding efficiency. Furthermore, the stir zones (SZ) demonstrated a marked improvement in tensile properties. Particularly, at the rotation rate of 80 rpm and axial load of 45 kN condition (below A 1), the microstructure featured ultra-fine ferrite and cementite, resulting in high hardness (270 HV) and tensile strength (704 MPa) in steel with just 0.08 wt% C, while maintaining nearly 80 % of the total elongation of BM. However, the SZ at 80 rpm exhibited an unusual decrease in local elongation despite the fine ferrite grain size and cementite presence. Electron probe microanalysis (EPMA) and nano-hardness revealed pronounced phosphorus segregation in the ferrite region and significant localized hardness disparities induced by the segregation behavior. The strain concentration at the interfaces between these regions during the tensile process leads to crack initiation and rapid propagation. The negative factor caused by the phosphorus segregation accelerates the failure of the specimen during the necking stage and ultimately shows decreased local elongation. • Friction stir welding of high-phosphorus (0.094 wt%) weathering steel. • Experimental analysis of local elongation of joints at various rotational rates. • EPMA characterization on phosphorus distribution. • Nano-indentation analysis of microstructures with different features. • Exploring the mechanisms of void formation and crack expansion. [ABSTRACT FROM AUTHOR]

This study assessed the atmospheric corrosion resistance of seven steel alloys, four custom-made and three commercially available, installed on a sheltered location on a bridge in Ontario-Canada. Visual inspection, SEM/EDS, thickness and weight gain measurement and electrochemical techniques were employed to investigate the protectiveness of patina. Results showed that small quantities of Cr, Mo, and P did not significantly improve the patina. Ni was effective, but the combination of Nb and B was crucial for enhancing it. Additionally, a linear correlation of average patina thickness and weight gain was observed for the alloys in this study. • Corrosion resistance of seven steel alloys, installed on a sheltered location on a bridge in Ontario, Canada, were studied after 10 years. • Cr, Mo, and P in small quantities did not significantly enhance the patina, Ni was effective. Combination of Nb and B improved patina's performance. • For sheltered locations, a linear correlation between patina thickness and corrosion weight gain was observed. [ABSTRACT FROM AUTHOR]