Steel Grades Research Articles

Complex Inhibitor Protection of Some Steels in Hydrochloric Acid Solutions by 1,2,4-Triazole Derivatives.

The behavior of low-carbon steels (LCSs), a high-strength steel and a nickel-chromium alloy in HCl solutions in the presence of N-containing organic substances has been studied. N-containing organic substances that comprise 1,2,4-triazole in their structure (substance I and substance II) provide comprehensive protection of various steel grades from corrosion and hydrogen absorption by the metal bulk in HCl solutions under both isobaric and isochoric conditions. All the compounds studied reduce, to varying degrees, the concentration of hydrogen adsorbed and absorbed by steel in HCl solutions. The most promising way to expand the scope of application is to use substance I in HCl solutions for protecting steels from high-temperature corrosion as a mixture with hexamethylenetetramine (HMT). In 2 M HCl (100 °C) under isochoric conditions, a mixture of compound I and HMT exhibited an excellent result: the degree of protection of LCS against corrosion was 99.5%. Substance I and its mixture with HMT protect steels not only in pure HCl solutions, but also in environments contaminated with hydrogen sulfide, which is especially important for the acid stimulation of wells in oil production.

Evaluation of radiation shielding effectiveness of some metallic alloys used in the nuclear facilities

Abstract Several nuclear shielding parameters were evaluated for stainless steel grades 304, 304 L, 316, and 316 L. The effective atomic number Zeff, mean free path (MFP), effective electron density Neff, half-value layer (HVL), and effective conductivity (Ceff) of the investigated alloys were evaluated via the mass attenuation coefficient (µ/ρ). The mass attenuation (µ/ρ) coefficients were computed for gamma-ray photons in the energy range 15 keV to 15 MeV using Phy-X/PSD program. Fast neutron attenuation was analyzed by computing the removal cross-sections (SR) using partial density method. The obtained results by Phy-X/PSD program were validated using Monte Carlo (MCNP4C) code. The stopping power of these alloys against e-1/H1/He+2 ions was evaluated using the ESTAR and SRIM Monte Carlo code, considering total stopping power (TSP) and projected range (PR). Furthermore, the transmitted neutron fraction at different neutron energies were calculated using Neutron Calculatro-V2 code for thermal neutrons (of energy 25.4 eV) and fast neutrons (with energies of 4 and 4.5 MeV). The obtained results showed that 316L alloy possesses good protection performance against gamma photons, charged particles, fast and thermal neutrons compared with other investigated alloys. Comparison of the calculated values revealed good agreement between Phy-X/PSD and MCNP4b. This work should be informative for the potential uses of these materials in the nuclear industry to build effective radiation shielding.

A novel intelligent control approach for lateral deviation in hot-rolled strip steel

This study presents an advanced intelligent control method that integrates ABAQUS simulation with the Derivative Dynamic Time Warping (DDTW) algorithm to enhance lateral deviation control in hot-rolled steel strips. Tested on a 2250 mm seven-stand tandem mill, the method incorporates a simulation model developed to assess control effectiveness under varying rolling conditions, including steel grades, strip widths, and thicknesses. The DDTW algorithm was employed to track the strip's centerline and accurately correct tail-end deviations, achieving over 96% accuracy. By combining real-time deviation data with the simulation, control precision was significantly enhanced, reducing deviation at the finishing mill exit by 20% compared to manual methods. Additionally, operator intervention was reduced by over 80%, and incident rates dropped by more than 60%, improving both process stability and product quality. These findings demonstrate the method's potential to optimize production consistency and minimize operational risks.

Experimental study and numerical simulation of precast segmental bridge columns with different design details for high seismic zones

In this study, five 1/3-scale bridge column specimens are experimentally and numerically investigated, which includes one cast-in-place (CIP) reference and four precast segmental columns with different design details. The four precast segmental bridge columns are of the same design details in terms of dimension and mild reinforcement, while different number of segments, various full-length connection rebar grades, presence of prestressing force, and two types of shear keys are compared. Seismic performance of the five specimens is compared under the same quasi-static cyclic loading protocol. Based on the experimental results, the precast segmental specimen solely using mild reinforcement exhibits similar seismic performance to the CIP reference, while segmentation slightly reduces post-yield stiffness and dissipated energy but increases the self-centering capability. Implementation of prestressing force significantly improves the self-centering capability of the columns, and higher grades of steel also increase the overall strength of the columns. Less number of segments in the column will lead to better structural integrity with smaller joint opening widths and higher energy dissipation capacity. A new finite element model is also proposed, and maximum deviation from test results is less than 2% in terms of stiffness and peak strength. This demonstrates that the Parallel material for rebar modeling and ZeroLength element for joint interface (including bond–slip behavior of rebar) simulation are both effective.

Investigation of the Effect of the Shape of Cutting Knives Limiting Burr in High-Strength Multiphase Steel Sheets.

In this study, numerical modeling and experimental tests of the sheet metal cutting process were carried out in order to determine the shape of the cutting knives for a roller shear, ensuring the minimization of burr on the cut edge. A rolling mill was used for the tests, enabling the replication of the cutting process in a roller shear (demonstrating the possibility of using cutting rollers). The cutting edges of the sheets were examined using light microscopy and then compared with the results of numerical simulations to determine the cutting quality. The tests were performed for multiphase Complex Phase (CP) grade steel. The initial thicknesses of sheets were equal to 1 and 2 mm. Based on the results of theoretical research, four shapes of cutting rollers were designed, of which two shapes were selected for experimental tests. The analysis of the test results shows that the lowest burr values were obtained for straight and beveled rollers. Analyzing the size of burr obtained in experimental tests, it can be concluded that for each of the two variants of the roller shape, a reduction in burr was achieved. Greater reductions in burr were achieved for shaped (cut) rolls.

Evaluating and optimizing metals for kitchen equipment production

This study assesses the mechanical properties and corrosion resistance of three stainless steel grades (316, 201, and 304) used in kitchen equipment manufacturing, emphasizing their performance based on specific metrics. Brinell hardness tests revealed values of 310.13 HB for 316, 286.49 HB for 201, and 276.13 HB for 304. Impact strength and tensile strength tests showed that 316 outperformed the others due to its higher chromium, nickel, and molybdenum content and enhanced mechanical properties from annealing, quenching, and tempering processes. Fatigue strength testing indicated that 316 had the highest endurance strength. Corrosion tests confirmed that all three grades exhibited no corrosion. These results indicate that stainless steel 316 has superior mechanical properties and corrosion resistance, making it an excellent choice for manufacturing durable and reliable kitchen equipment.

Ways to improve the technology for producing axle steel grades

Ways to improve the technology for producing axle steel grades

Research of fracture mechanism of steel grade P91 on impact bending after preheat treatment before welding

Research of fracture mechanism of steel grade P91 on impact bending after preheat treatment before welding

Exploring the correlation among grades of austenite stainless steel and surface treatment for anodic electrodes under alkaline water electrolysis

Exploring the correlation among grades of austenite stainless steel and surface treatment for anodic electrodes under alkaline water electrolysis

Detection of Rail Defects Using Phased Array Ultrasonic Technique

The Phased Array Ultrasonic Technique (PAUT) is an advanced non-destructive inspection method that utilizes an array of ultrasonic testing (UT) probes consisting of several small elements. The laboratory used an artificial crack on the rail steel grade 900A/ R260 test block to study the principles of PAUT and how to measure the defect’s reliability and accuracy. On-site studies were done on railroad tracks with different structures. Rail steel grade 900A/ R260, Hadfield steel, and thermite welded joints. No defects were found during the inspection at the crossing nose of the two positions. Only a darker shade of color in the area has an impact load from the wheel applied when a train changes to another direction. Inspection was also performed for the Thermit welded rail joint with two position defects. The inspection results found defects such as porosity, with an echo (A%) value exceeding 80%, but it does not require rejection according to the BART standard.

THERMAL CALCULATIONS OF RAPID HEATING AND COOLING DURING TESTING THE TECHNOLOGY OF COMBINED SURFACE HARDENING OF WELDED PARTS WITH A WORKING PART MADE OF 15X11MF STEEL

Hardening of contacting surfaces is aimed at improving the material properties of components to ensure more efficient operation of mechanisms and devices. There are many surface modification technologies, such as: creating surfacing on the surface, creating coatings, forming surface layers using various techniques, and other technologies. Such technologies are aimed at improving the mechanical and tribological properties of materials and products made of them. Combined surface hardening using friction is a hardening method that can significantly improve the mechanical and tribological properties of materials. Thermal calculations of the process are an important aspect for controlling this hardening method. In this regard, there is an urgent need to perform thermal calculations of the process of rapid heating and cooling after heating during testing the technology of combined surface hardening of welded parts. the purpose of this work is to perform thermal calculations of the cycle of rapid heating and cooling after heating during surface hardening of welded parts with a working part made of 15X11MF steel. This steel grade is a structural alloy steel with increased corrosion resistance. Combined surface hardening was performed on a friction treatment unit. The source of heating in the combined surface hardening technology is the friction that occurs between the tool, a rotating steel disk, and the surface of the workpiece. To analyze the temperature distribution from the surface deep into the samples during combined surface hardening, the heat conduction problem was solved using the source method. The problem of heat conduction was solved in a coordinate system that moves with the heat source, i.e., with the contact surface The input parameters for calculating thermal phenomena during the combined surface hardening of the studied material were: a - thermal conductivity coefficient; λ - thermal conductivity coefficient; аф - actual value of the machining depth taken from the side where the microgroove was made; r is the radius of the disk; L is the length of contact between the disk and the sample surface during sample processing; y is the heat source criterion - the isotherm value of 150 °C, taken from the side where the grinding was performed. The result of thermal calculations according to the shape of the source is the temperature field from an instantaneous source of the corresponding shape. The temperature field is shown in the boundary plane of the sample plate section and demonstrates to what depth and temperature the sample was heated during processing To evaluate and analyze the thermal cycle of steel heating and cooling during machining, a corresponding heating-cooling graph was calculated and plotted, which makes it possible to calculate the actual cooling rate in the surface layer of the samples during machining. The expediency of applying this technology in terms of a high-speed method of heating and cooling the surface layer of the processed parts is shown. The data obtained make it possible to calculate the cooling rate of the surface after heating in the process of combined surface hardening, or the cooling rate at any depth of the part sample within the temperature field that occurs during its processing, which is planned infurther research.

Research of the Features of Stress-Corrosion Destruction of Gas Pipelines

The problems of stress corrosion or hydrogen blistering of gas pipelines are relevant and require careful study of the causes and factors that cause this type of corrosion-mechanical destruction of pipelines. The analysis of numerous publications on this problem revealed contradictions of information regarding the mechanism of stress corrosion and a lack of experimental materials on the substantiation of the nature and peculiarities of the nature of destruction on gas pipeline networks. Systematic experimental studies using different brands of pipe steels allowed to determine the brands of steels, which according to their characteristics are the most resistant to VBR in harsh operating conditions, including even in the most aggressive NACE environment with H2S and CO2 additives at a pressure of 10-15 atm. Moreover, the experimental studies were as close as possible to the operating conditions of pipelines of the gas transportation network. The obtained results of experimental studies can serve as a basis for developing methods of technical diagnostics and forecasting the actual state of pipelines, which will significantly prevent the occurrence of sudden destruction caused by stress corrosion. The influence of the service life of gas pipelines on the degree of flooding and microhardness of pipe steels was established, which made it possible to substantiate the embrittlement of the metal with the increase of service life. The values of impact toughness on samples with sharp and round notches and the amount of work of crack growth depending on the service life of the pipe steels were determined, which made it possible to choose steel grades characterized by the highest resistance to brittle fracture. It is shown that with the service life, the destruction occurs according to a brittle mechanism, which is confirmed by the increase in the share of the fibrous component in the fractured samples after impact tests. It was established that the lowest corrosion rate is possessed by new grades of improved steel grades 20А and 08 KhMChA.The PRFNV parameter proposed in the paper makes it possible to assess the susceptibility of pipe steels to stress corrosion cracking and provides an opportunity to regulate the corrosion crack resistance of pipelines by metallurgical methods.

Features of the calculation for the fatigue of tower structure

This article describes the effect of the phenomenon of vortex shedding under the action of frontal wind on tower structures of solid crosssection.The phenomenon of vortex shedding occurs at wind speeds higher than certain critical ones, which on the Beaufort scale correspond to weak and moderate winds with a very large number of cycles, which requires the calculation of structures forendurance. An additional feature of this aspect is that the phenomenon of vortex shedding is quite unknown in broad engineering practice in Ukraine and for the first time a reference to the need to calculate structures for vortex excitation appeared with the introduction of Amendment 2 to DBN V.1.2-2:2006 "Loads and influences. Design standards" only in 2020. This article provides an analysis of existing calculation methods and the state of the provisions of national standards for thecalculation of tower structures for complex wind effects. In particular, the problems of calculating structures for dynamic action when calculating for frontal wind are indicated. The critical speeds for real tower structures and the approximate number of vibration cycles per year occurring during normal operation were also estimated. It was found that thenumber of cyclic self-oscillations from vortex shedding with a stress asymmetry coefficient ρ=-1 is from 2 to 15 million per year, which indicates the need to limit the stresses in structures and their details to the values of the endurance limit. Thearticle provides calculations of the values of the endurance limits for different groups of structures, analyzes the feasibility of using high-strength steel grades. An analysis of the reduction in the number of cycles when stresses exceed the endurance limit is also performed and it is proven that insignificant excesses of stresses within 3..5% can significantly reduce the endurance of structures by several times.This conclusion is especially relevant when calculating lattice-type space-frame structures that have an external enclosing shell that creates a wind effect in the structure similar to a solid-wall structure. Such features are relevant primarily for largescale monumental structures.

Influence of the shape of abrasive soil particles on the regularities of destruction of structural steels during wear

The article presents the results of studying the patterns of destruction and their influence on the wear resistance of structural steels: steel 45, steel 65G and steel 28MnB5 when moving in soils with different abrasive particle shape factors. The phenomenon of the presence of a critical abrasive particle shape factor (CPSF) was established, up to which the wear resistance of steels decreases. In the supercritical region, wear resistance is stabilized, and the differences between its values of the studied steels are significantly reduced. When forming wear resistance, the role of the particle shape factor is to regulate active deformation and fatigue phenomena by means of the level of external force action on the working surface and is realized through the rheological-fatigue parameter, which is controlled by the cyclic viscosity of steel deformation. In this regard, the choice of structural steel grade for the manufacture of machine parts intended for use in soils with different abrasive particle shape factors must be made based on its ranking by the rheological-fatigue parameter. It is shown that in the strength basis of the steel wear mechanism under sliding friction in soils with different particle shape factors, in addition to the resistance to the propagation of axial and radial fatigue cracks in the destructive deformation layer, an important role is played by the resistance to the initiation and propagation of lateral fatigue cracks at its boundary with the plastic-destructive deformation layer, and the mechanical component of the contact interaction is decisive. It is established that under wear in soils with different particle shape factors, the action of the softening process is more effective than the hardening process. In the supercritical region, the intensity of steel softening is significantly reduced due to the increase in the effectiveness of the hardening action due to the dispersion hardening of steel. However, no qualitative changes in the metal wear process are observed

Atmospheric Corrosion of Different Steel Types in Urban and Marine Exposure.

The aim of the present work is to study the atmospheric corrosion behavior of metals exposed to both urban (Milan, IT-Lombardia) and marine (Bonassola, IT-Liguria) atmospheres in Italy. A number of coupons (100 × 150 mm) of carbon steel (CS), hot-dip galvanized steel (GS) and different grades of stainless steel (SS) were exposed. At fixed periods of time, samples were characterized by means of Linear Polarization Resistance (LPR), mass loss tests and corrosion product analysis. The corrosion rate on carbon steel exposed to an urban atmosphere, obtained by means of mass loss tests and LPR, are in good agreement with the value estimated by the dose-response function according to the ISO 9223 standard. The yielded results can be classified in corrosivity class C2 of the same ISO 9223. Similar measurements on galvanized steel exhibited a coherent average corrosion rate. Higher corrosion rates were measured for samples exposed to a marine atmosphere for both materials, with values belonging to exposure classes C4-C5 for both materials. Stainless steel samples exhibited only superficial staining in the case of marine exposure, even after just a few months.

Influence of nonlinearities in longitudinal bars on overstrength P–M capacity of RC columns and piers

AbstractThe actual capacity of a reinforced concrete (RC) structure is determined by the overstrength capacity of individual members. RC members can undergo six stages (namely cracking, yielding, spalling, buckling, crushing and rupturing) depending on the cross‐section geometry, reinforcement detailing, and type of loading. For members under compression and flexural actions, buckling of longitudinal bars becomes the ultimate stage in the load‐deformation curve of RC member. Hence, to assess the capacity of RC members, it is essential to have load‐deformation relation of individual bars considering nonlinear effects. This paper presents a simplified analytical procedure of nonlinear analysis to obtain the nonlinear load‐deformation curve of reinforcing bars. The proposed method uses combined geometric and material nonlinearity. The method is compared with the experimental test results from the literature and has shown a good match. Furthermore, the effect of initial imperfection and slenderness of the reinforcing bars on the overall performances have been studied and discussed. This inelastic relation of reinforcements has been used to obtain the P–M interaction diagram of the RC member, demonstrating the effect of nonlinearity in the longitudinal bars. Fiber modeling approach has been used to draw the P–M curve, considering confinement of concrete, bilinear stress–strain of steel under tension and nonlinear under compression. Implications of amount of longitudinal reinforcement, grade of steel, initial imperfection and section size on the P–M curve have been studied. Results show that the nonlinearity of the longitudinal bar can reduce the capacity of the member by 15%. The strength reduction is higher for higher percentage of reinforcements and slender bars. This indicates that the P–M interaction curve exists at three levels, and is discussed in detail in the paper. It is recommended that the effect of bar nonlinearity should be considered in the capacity assessment of RC members.

Electrochemical Analysis on Corrosion of Stainless Steels in Molten Nitrate Salt

Electrochemical analysis of corrosion in molten nitrate salt of stainless steel grade SS 430, SS 2205, SS 2507 and SS 304 is directly performed to evaluate corrosion resistance. Stainless steels are exposed to molten nitrate salt at 600 °C for two hours. This is done in a furnace equipped with a working electrode terminal, reference and counter electrodes. According to this, electrochemical impedance spectroscopy and potentiodynamic polarization techniques are applied in situ to measure corrosion rates and corrosion resistance. Microstructures of stainless steel reveal the ferrite phase for SS 430, the austenite phase for SS 304 and the duplex phase for SS 2205 and SS 2507. In this study, the existence of an austenite phase promotes corrosion resistance in molten nitrate salt.

Combination of Ultrasonic Cavitation and Sanitizing Agents to Reduce Bacterial Biofilm on Stainless Steel

Pathogenic bacteria can contaminate in food products and line productions that causing foods spoilage and foodborne diseases. Biofilm is the important structure to support the survival and adherence of bacteria on materials from cleaning practices. Therefore, this research aimed to investigate the combination of sanitizing agents and ultrasonic cavitation for elimination of bacterial biofilm stained on stainless steels grade 316 L. Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli were proliferated by UHT milk, palm juice, and LB broth including the construction of their biofilm on stainless steel. Growth characteristics of all bacteria cultured with LB broth exhibited 9.60 log cfu/mL that greater than UHT milk, and palm juice after incubation at 37°C for 24 hours. Particularly, E.coli that cultured with every liquid culture medium has highly constructed biofilm on stainless steel, compared to other strains. The highest reducing biofilm value of P.aeruginosa, S.aureus, and E.coli after the elimination processes with sanitizing agents and ultrasonic cavitation have been discovered 89.34%, 88.46%, 81.13%, respectively.

Influence of chemical composition of steels for production of grinding balls on their deformation characteristics

The conducted studies determined the patterns of influence of chemical composition and deformation parameters of ball steels with experimental chemical composition on their deformability. The development of experimental chemical compositions of ball steels was carried out based on the existing experience of domestic and foreign researchers, taking into account the possibility of further application of the obtained results for ball steels of standard grades. The studies were carried out using a specialized laboratory installation by the method of hot-rolling samples. An increase in the carbon content in the range of 0.72 ‒ 0.85 %, manganese in the range from 0.72 to 0.85 %, chromium in the range of 0.38 – 1.71 % and nickel in the range from 0.08 to 0.87 % has a significant effect on increasing the deformation resistance of steels. At the same time, the quantitative effect of carbon content in the steels on their deformation resistance is much more pronounced in relation to manganese, chromium and nickel. It was determined that a decrease in the deformation temperature from 1200 to 900 °C, an increase in the deformation rate in the range from 1 to 10 s–1 and true deformation in the range 0.05 ‒ 0.35 cause an increase in the deformation resistance of ball steels, regardless of their chemical composition. The influence of all these parameters on the deformation resistance of steels has a pronounced nonlinear character and the deformation temperature has the greatest relative influence on the deformation resistance. The data obtained are summarized in the form of a multiple regression equation, which establishes the quantitative relationship between the resistance of steel to deformation with its chemical composition and deformation para­meters. Verification of the adequacy of the obtained equation in relation to the rolling conditions of ball steel billets of standard grades at the continuous medium-grade mill 450 of JSC EVRAZ United West Siberian Metallurgical Plant confirmed the possibility of using it to predict the energy-power parameters of rolling ball steels of various chemical composition.

Ensuring the quality indicators of the surface layer of parts made of 30KhGSA steel by laser microstructuring

The purpose of the work was to study the influence of laser microstructuring modes on the formation of qualitative indicators (the length of the laser exposure zone, microhardness) of the surface layer of parts made of hot-rolled sheet steel grade 30KhGSA.Methods. The structural medium-alloy steel of the 30KhGSA grade in the hot-rolled state (sheet 6 mm thick) was chosen as the object of research. Special samples were produced by laser cutting to study changes in the structure, structure and microhardness of the laser exposure zone. After laser cutting, one of the sides of the sample was subjected to mechanical milling in order to remove a layer with a modified structure of the material obtained during laser cutting. Next, laser microstructuring of the sample surfaces was performed using a continuous fiber laser. Metallographic and durometric studies were carried out to study the effect of laser microstructuring on changes in the structure and quality of the surface layer.Results. The peculiarities of changing the microstructure of the laser exposure zone depending on the type of laser treatment are considered. It is shown that, regardless of the type of laser treatment, a "white layer" is formed on the heat-strengthened surface, the thickness of which depends on the parameters of laser radiation: power, speed, spot diameter, focal length. It has been revealed that when milling operations are used as a preliminary mechanical treatment of the cutting edge surface, in the vast majority of cases a white layer is not formed.Conclusion. The results obtained can be used to create resource-saving material processing processes using highly concentrated energy flows.