Steel 09G2S Research Articles

Development of calibration samples made of steel 45 and 09G2S for eddy current structuroscope by carburizing

The paper describes the process of carburizing and hardening of 45 and 09G2S steels for the production of samples for the development of a technique for eddy current testing of the quality and thickness of hardened layers on ferromagnetic cores. Structural analysis of samples in the initial state, in the hardened state, as well as after carburizing and hardening was carried out. As a result of metallographic studies it was obtained that the depth of the cemented layer of steel 45 was equal to 250 microns, and in case of steel 09G2C it is in the range of 550-800 microns.

Features of the Lath Microstructure in the Heataffected Zone of the 09G2S Steel After Manual Arc Surfacing

Features of the Lath Microstructure in the Heataffected Zone of the 09G2S Steel After Manual Arc Surfacing

Magnetic properties and structure of carbon steel samples manufactured by selective laser melting and subjected to fatigue tests

This study investigates the magnetic properties and structure of 09G2S steel samples fabricated using casting and selective laser melting methods. Fatigue bending tests with cantilever fixation were performed to analyze these properties. It was found that the fatigue curve for 3D-printed steel lies below that of cast steel with a similar chemical composition. Both the coercive force and residual magnetic induction are lower near the fracture site. The greater the number of cycles to failure, the smaller the difference in coercive force and residual magnetic induction in different parts of the sample. The nature of fatigue failure differs between cast and 3D-printed steel. The cast 09G2S steel sample exhibits a straight and homogeneous fatigue fracture without visible crack initiation sites. In contrast, the 3D-printed steel samples show heterogeneous fractures with localized zones of failure and tear-off ridges.

Evaluation of the Technical Condition of Pipes during the Transportation of Hydrogen Mixtures According to the Energy Approach

In this study, a theoretical–experimental methodology for determining the stress–strain state in pipeline systems, taking into account the hydrogen environment, was developed. A complex of theoretical and experimental studies was conducted to determine the specific energy of destruction as an invariant characteristic of the material’s resistance to strain at different hydrogen concentrations. The technique is based on the construction of complete diagrams of the destruction of the material based on the determination of true strains and stresses in the local volume using the method involving the optical–digital correlation of speckle images. A complex of research was carried out, and true diagrams of material destruction were constructed, depending on the previous elastic–plastic strain and the action of the hydrogen environment. The change in the concentration of hydrogen absorbed by the material was estimated, depending on the value of the specific energy of destruction. A study was conducted on tubular samples, and the degree of damage to the material of the inner wall under the action of hydrogen and stress from the internal pressure was evaluated according to the change in specific energy, depending on the value of the true strain established with the help of an optical–digital correlator on the outer surface, and the degree of damage was determined. It has been established that the specific fracture energy of 17G1S steel decreases by 70–90% under the influence of hydrogen. The effect of the change in the amount of strain energy on the thickness of the pipe wall is illustrated.

THE METHOD OF MECHANICAL TESTING AND INVESTIGATION OF THE POSSIBILITY OF FATIGUE STRENGTH CONTROL BY THE MAGNETO-NOISE METHOD OF STEEL SAMPLES MANUFACTURED BY ADDITIVE TECHNOLOGY

Steel products manufactured using additive technologies are an alternative to traditional methods of their production. The specific method of their forming actualizes the issue of strict control of their quality, including fatigue strength. To investigate the possibility of control on the samples of low-alloyed steel 09G2S produced by selective laser alloying and, for comparison, by casting method, it is proposed to use the magnetic noise method. For mechanical tests of specimens in bending a simple original portable stand was created, a methodology of fatigue strength research and a program of specimen testing were developed. The tests have shown the efficiency of using the methodology and the bench in the study of fatigue strength. The results of evaluation of local heterogeneity of specimen properties before cycling and the effect on the magnetic noise level of the number of cycles at the initial period of loading at low cycle amplitude are presented.

Dislocation Structure in a Strain Localization Band Formed in Normalized 09G2S Steel under Tension

Dislocation Structure in a Strain Localization Band Formed in Normalized 09G2S Steel under Tension

Разработка перфорированного элемента рабочего органа глубокорыхлителя: топологическая оптимизация

The development or modernization of tillage machinery aims to increase its service life and efficiency and reduce the negative impact on the soil. In order to increase the efficiency of agricultural machines, the author attempted to optimize the working element of a subsoler - its plate - through topological and parametric modeling. The subsoiler plate with the mass of 1.925 kg with maximum stresses 176.8 MPa was used as a base model. The author determined the plate zones having the least influence on the stiffness and strength of the implement structure. When designing the modernized plate, the following parameters were taken into account: safety factor on the ultimate strength - 1.5 to 2; maximum mass reduction - less than 50%, minimum reduction - more than 10%. The plate is manufactured by laser cutting from 09G2S or 30XGSA steel. The manufacturing process, strength and wear characteristics, and cost were considered to be not lower than the base variant. The algorithm developed in the SysML system modeling language helped systematize the process and establish functional and non-functional requirements and limitations. Using Autodesk Fusion 360 automatic design system, the author developed the rational geometric shape of the soil cultivation plate of the subsoiler with a mass of 1.585 kg and a maximum stresses of 169.5 MPa according to this algorithm. Topological optimization resulted in a 17.67% reduction in the part’s weight at the second iteration while maintaining strength and wear resistance characteristics. By determining the thickness of the element, the author established compliance with the safety factor requirement. Samples of subsoiler plates with thickness of 16 mm were made of 09G2S steel. To confirm the calculated strength characteristics it is necessary to carry out laboratory and field tests of the prototype of the lightweight design.

Влияние предварительной плазменной обработки поверхности стали 09Г2С на формирование покрытия в результате горячего цинкования

In recent years, the range of silicon-containing steels subjected to hot galvanizing has been expanding. Alloying of steel with 0.5–1 % of silicon leads to the formation of a zinc coating of great thickness with a matte or multi-colored surface. This is associated with the changes in phase reactions between iron and zinc in the Fe–Zn–Si system. The development of ways to neutralize the negative influence of silicon on the formation of zinc coating is an urgent task. The purpose of the work is to study the influence of preliminary plasma cutting and plasma surface hardening of 09G2S (S355J2) steel on the thickness and structure of zinc coating formed on treated surfaces. It was found that after plasma cutting, the structure of the surface layer of steel is martensite, and after plasma surface hardening, it is martensite and ferrite. Analysis of the change in microhardness from the steel surface to the middle showed that the hardened layer depth is 400 μm. A zinc coating consisting of a δ-phase and a ζ-phase is formed on the surface of the steel without pretreatment. On the surface of the steel after plasma treatment, a zinc coating is formed characteristic of low-silicon steels and consisting of the δ-phase, ζ-phase, and η-phase. It was found that the thickness of the zinc coating on the surface after plasma cutting is two times less than on the untreated surface, and the reduction in the coating thickness occurs due to a decrease in the ζ-phase thickness. A hypothesis was suggested that the martensite formation on the steel surface leads to the disappearance of the ordered FeSi phase and changes the phase equilibrium in the Fe–Zn–Si system. Consequently, preliminary plasma treatment of the steel surface allows controlling the structure and thickness of the resulting zinc coating and is therefore recommended for introduction into the hot galvanizing process of silicon-containing steels.

Structure Formation in 09G2S Steel Produced by Additive Electric Arc Growth

Structure Formation in 09G2S Steel Produced by Additive Electric Arc Growth

Application of acoustic emission method to evaluate the changes in the properties of 17G1S steel after long-term service

Application of acoustic emission method to evaluate the changes in the properties of 17G1S steel after long-term service

DEVELOPING ALGORITHM FOR DIGITAL TWIN OF WELDED JOINT IN SHELL STRUCTURE (PART 1)

Most of oil and gas equipment is welded shell-type structures. Their operation may cause accidents of different complexity. Despite the fact that such structures go through technical diagnostics and life cycle analysis, the current accident statistics does not suggest any improvements. Nowadays there is a rapidly-developing line of research that focuses on creating so-called digital twins. These are numerical models that are based on real mechanical characteristics, dimensions and changes that may occur during the operation of the facility. These models allow using diagnostic data for assessing the remaining service life. While mechanical engineering deals with mass-produced products and has a large database of equipment failures, shell-type oil and gas facilities are mostly specific and their reliability database can barely be useful for predicting their performance. A number of studies on digital twins suggest heterogeneity in physical, mechanical and geometric properties pattern of shell-type structures. Some attempts to cover these properties in numerical models proved that it is actually possible to predict the areas where damage would occur most frequently and cause breakdown. However, in order to keep improving the quality of the modelling system, it is necessary to consider the properties of welded joints.This article deals with analyzing welded joints properties which are essential for developing an algorithm for a digital twin of a welded cylindrical shell. The study revises welded joints of pipe billets made of 09G2S steel. The equipment used meets all the standards concerning welded joints. Properties are distributed unevenly across the welded joint, the weld-affected area and the base metal. These areas are exposed to intensive sound waves within the human hearing range. As a result, they generate secondary acoustic emission signals. When intercepted and analyzed, the signals indicate local heterogeneity. Therefore, welded joints produced by joining weldless billet pipes were inspected by secondary acoustic emission analysis and the Expert-19 device. The test allows analyzing the acoustic properties of a sound wave that went through the welded joint. Before the experiment, it was determined how the measured properties correlate with the distance between the Leeb (D-type) sensor and the microphone that detected the sound wave and specified its characteristics for the numerical analysis. The analysis involved a special computer program. The sound-wave propagation was analyzed along the axes of the shell, its circumference and across the width. Since the properties of the welded shells were measured both before and after the welding, the data on distinctive changes all along the structures’ surface has been obtained for the first time. Also the test has for the first time determined the peculiar features of integral parameter distribution within the entire shell. Response level of acoustic-wave propagation to the heterogeneity has been illustrated in terms of both quality and quantity.

Influence of Overheating on High-Cycle Fatigue Characteristics of the Base Metal and Weld Metal of Low-Carbon Steel Welded Joints

The results of a high-cycle fatigue testing of our samples were obtained, and a comparative assessment of the properties of the base metal and weld metal of 09G2S-type steel (13Mn6 according to the DIN17145-80 standard) before and after overheating (1200 °C, 3.7 h) was performed. The welded joints between the sheets of 09G2S steel were obtained through automatic argon arc welding. The fatigue tests were carried out under repeated tensile loading. The “maximum cycle stress—number of cycles to failure” fatigue curves of the samples were plotted. The fracture surfaces of the samples were studied, and the fatigue failure mechanisms were analyzed. It was shown that, during testing, all samples demonstrated cyclic hardening behavior. The samples of the base metal as delivered had the highest endurance limit, and the smallest endurance limit was found in the samples of the base metal and weld metal after overheating, the endurance limits of which were similar. The fracture mechanism of all samples was quasi-brittle with the presence of very thin fatigue micro-grooves. The final rupture of all samples had a ductile dimple type.

Використання методу акустичної емісії для оцінки змін властивостей сталі 17Г1С після тривалої експлуатації

Використання методу акустичної емісії для оцінки змін властивостей сталі 17Г1С після тривалої експлуатації

Comparative investigation of electrolytic hydrogenation of pipe assortment steel under cathodic polarization

Comparative studies of electrolytic hydrogenation of pipe steels in NS4 electrolytes under cathodic polarization were carried out. It was established that the dependence of hydrogen concentration penetrating through steel under cathodic polarization in the NS4 electrolyte on the polarization potential is nonlinear, and differs for steels of different chemical compositions. Hydrogenation of pipe steels resulted in changes in their electrochemical properties. Null current potential tends to shift to more negative values as the cathodic polarization potential increases (by absolute value) from −0.75 V to −1.2 V. Polarization resistance of the partial anodic reaction for all steels increases non-monotonically with different intensities. A dependence diagram of hydrogenating from the steel strength under cathodic polarization is drawn and analyzed. It was established that at the minimum protective potential of −0.75 V, hydrogenation of all the steels is not happening. At a potential of −0.95 V, the maximal hydrogenation is observed for steel with the lowest ultimate strength, and at the maximum protective potential of −1.05 V – hydrogenation susceptibility changes non-monotonically. Under more cathodic polarization at a potential of −1.2 V, steel 09G2S with the lowest ultimate strength hydrogenated most strongly, and steels with similar ultimate strength indicators have a similar tendency to hydrogen penetration.

INVESTIGATION OF FRACTURE MECHANISMS OF 09G2S STEEL ACOUSTIC EMISSION METHOD

The destruction mechanism during static stretching of flat samples of structural steel 09G2S in a defect-free state and with an artificial defect in the form of a fatigue crack are studied using the method of acoustic emission and fractographic analysis of surface violations.

Static, Dynamic, and Shock-Wave Strengths of 17G1S, 09G2S, 10G2FBYu, and K60 Strength Class Pipe Steels

Static, Dynamic, and Shock-Wave Strengths of 17G1S, 09G2S, 10G2FBYu, and K60 Strength Class Pipe Steels

Failure Kinetics of 3D-Printed 09G2S Steel Produced by Electric Arc Surfacing

Failure Kinetics of 3D-Printed 09G2S Steel Produced by Electric Arc Surfacing

Acoustic Emission Study of the Fracture Mechanisms in 09G2S Steel

Acoustic Emission Study of the Fracture Mechanisms in 09G2S Steel

Study of fatigue structural changes in specimens of 09G2S steel obtained by the WAAM method

Study of fatigue structural changes in specimens of 09G2S steel obtained by the WAAM method

Detection of prefracture zones in structural materials by magnetic and optical methods

The study of the applicability of magnetic and optical methods to the detection of prefracture zones under fatigue degradation of structural materials is exemplified by the 09G2S steel. The regularities of changes in the signal of an attached fluxgate gradiometer with the increasing number of loading cycles have been revealed; namely, significant changes in the gradiometer readings on individual specimen surface areas prove to result from the formation of fracture zones. The change in the value of the coefficient of correlation among the speckle images is studied at different stages of cyclic testing. Speckle image heterogeneity is shown to appear due to fracture nucleation. Thus, the applicability of magnetic and speckle-interferometric methods to detecting prefracture zones in objects under cyclic loading is substantiated.