30KhGSA Steel Research Articles

Structure and properties of 08KhMFA and 30KhGSA steels obtained by electric arc welding

Structure and properties of 08KhMFA and 30KhGSA steels obtained by electric arc welding

Change in structure and properties of high-speed steel deposited layer after tempering and electron beam processing

The structure and properties of multilayer coatings made of high-speed R18Yu steel formed on a substrate of 30KhGSA steel during multilayer plasma surfacing in a mixture of argon and nitrogen followed by high-temperature tempering and electron beam processing are studied using the methods of light, scanning and transmission electron microscopy. Plasma surfacing forms a layer, the main phases of which are α-Fe and carbides of М6С(Fe3W3C–Fe4W2C) composition, forming a frame mesh. After high-temperature tempering, particles of the carbide phase of globular or faceted shape are identified in the bulk of α-Fe with sizes from 10 to 38 nm. The microhardness of the deposited layer made of R18Yu steel increases after tempering and is 5.3 GPa. Electron beam processing is accompanied by a multiple (3 or more times) reduction in the wear parameter (increased wear resistance of the material); the microhardness of the modified layer does not change and is 5.3 GPa.

Erratum to: Structure and Properties of Multicomponent Diffusion Boride Coatings Formed on a Hardened 30KhGSA Steel Surface

Erratum to: Structure and Properties of Multicomponent Diffusion Boride Coatings Formed on a Hardened 30KhGSA Steel Surface

Industrial application of diamond-electrochemical honing method

The method of diamond-electrochemical honing (DEH) is a finishing method that provides the required characteristics of surface roughness, the distribution of residual surface stress diagrams, which ultimately ensures the formation of a high-strength electroplated coating. This article presents studies of changes in surface roughness, residual stresses and other parameters depending on the selected DEH modes for parts made of steels 30KhGSA, 30KhN2MFA, 35KhN2MFASH, 50A. The article presents the design of the instrument-khon; with the solution of the issue of the geometric characteristics of the cathode part, the insulating coating and the material of the hone tool guides. The regime support of the DEH was formed on the basis of studies, the results of which are given in the article. The selected kinematic-geometric indicators of the hone-tool — workpiece system make it possible to form the drives of the DEH equipment. The optimal composition of the DEH electrolyte was chosen with the creation of an electrolyte storage and supply system. The article contains the results of studies demonstrating the effect of DEH on the reliability and durability of parts subject to the use of this method. Data on the technical and economic efficiency of the created industrial site of the DEH are presented.

Influence of tempering on structure of deposited high speed steel coatings

The technology of plasma surfacing in a protective-alloying nitrogen medium with an additive powder wire is characterized by high productivity and the possibility of alloying the deposited metal. Durability of metal products depends on microstructure, chemical composition, production technology, modes of thermal and surface treatments. The article presents the results of a study of structure and microhardness of the high speed alloy R18Yu deposited in nitrogen medium on medium-carbon steel 30KhGSA. There were no differences in structure of the surfacing layer up to 4 mm in depth, but after four times high-temperature tempering at 580 °C, structural and phase changes were revealed. The values of microhardness after surfacing and tempering are consistent with the literature data.

INVESTIGATION OF THE PROCESS OF ELECTRIC ARC METALIZATION OF COATINGS FROM STEEL 30KhGSA

The article considers the electric arc metallization technological modes of steel 30KhGSA wires, which affect thestructure formation and properties ofcoatings.Electric arc spraying was carried out using an SX-600 electric arc metallizer. The properties and characteristics of the resulting coatings depend on several plating parameters such as wire feed speed, voltage, and amperage. The coating structure was studied by electron microscopy and metallographic analysis. The coating has a layered structure, which consists of frozen convective metal flows, micro-welded small metal particles and oxides. The results of the study show that an increase in the wire feed speed during metallization leads to an increase in the resulting coating thickness per unit time. On the surface of steel 45, depending on the selected mode, coatings were formedfromsteel30KhGSAwithathicknessintherangefrom50μmto370μm.Ithasbeenestablishedthat when electric arc metallization coatings are sprayed with 30KhGSA wire, the microhardness of the surface layer increases by a factor of 2 relative to the microhardness of 45 steel. Based on studies investigating the impact of various factors in the electric arc spraying process on the formation of coating structures and properties, it can be deduced that utilizing electric arc metallization on steel 30KhGSA substrates allows for the production of coatings with enhanced hardness.

Study of the Effect of Thermal Diffusion Borosiliconizing on the Structure and Properties of the 30KhGSA Steel

Study of the Effect of Thermal Diffusion Borosiliconizing on the Structure and Properties of the 30KhGSA Steel

Structure and Properties of Multicomponent Diffusion Boride Coatings Formed on a Hardened 30KhGSA Steel Surface

Structure and Properties of Multicomponent Diffusion Boride Coatings Formed on a Hardened 30KhGSA Steel Surface

Industrial Application of the Diamond-Electrochemical Honing Method

The method of diamond-electrochemical honing (DEH) is a finishing method that provides the required characteristics of the surface roughness, the distribution of the residual surface stress diagrams, which ultimately ensures the formation of a high-strength electroplated coating. This article presents studies of changes in the surface roughness, the residual stresses, and other parameters depending on the selected DEH modes for the parts made of steels 30KhGSA, 30KhN2MFA, 35KhN2MFASH, 23KhGS2MFALU, and St. 50A. The article presents the design of the instrument-khon; with the solution of the issue of the geometric characteristics of the cathode part, the insulating coating and the material of the hone tool guides. The regime support of the DEH was formed on the base of the studies whose results of are given in the article. The selected kinematic-geometric indicators of the hone-tool – a workpiece system make it possible to form the drives of the DEH equipment. The optimal composition of the DEH electrolyte was chosen with the creation of an electrolyte storage and a supply system. The article contains the results that demonstrate the effect of DEH on the reliability and durability of the parts subjected to the use of this method. The data on the technical and economic efficiency of the created industrial site of DEH are presented.

Structure formation of Np-30KhGSA alloy in wire and arc additive manufacturing

The use of metallic products 3D-printing is a modern, promising technology that improves production efficiency. However, using this technology is associated with a number of problems, for example, with increased microstructural heterogeneity and defects in metal. Therefore, it is necessary to carry out researches to identify 3D-printing modes ensuring the most homogeneous, stable and non-defect structure. In this work, a study was made of the process of structure formation of 30KhGSA steel in the process of Wire and Arc Additive Manufacturing (WAAM) under various printing modes. Microstructural analysis, microhardness measurement and fractal analysis were used for assessment of the obtained billets. In all surfacing modes, a significant structural inhomogeneity of the deposited billet was revealed, which is explained by the thermal effect of the deposited layer on the already crystallized metal. Nevertheless, we found the mode that gives the most favorable microstructure in terms of its uniformity and equiaxed grains. With an increase in WAAM heat input values, an increase in the productivity of the process is observed and a decrease in the number of pores in the material is recorded. However, when the heat input of the surfacing process exceeds 1000 J/mm, the structural inhomogeneity of the material increases and its microhardness significantly decreases. Based on the studies, as a WAAM 3D-printing mode for Np-30KhGSA alloy, a mode with a heat input of about 920 J/mm can be chosen, which provides the lowest structural inhomogeneity and a sufficiently high productivity of the growth process with the absence of defects in the form of pores and elements of not melted wire.

Hardening technology of metallurgical equipment parts by high-speed nitrogen alloys

The technology for hardening of metallurgical equipment parts by high-speed alloys with high nitrogen content is developed. The manufacturing process of deposited parts includes: machining of the workpiece, plasma surfacing, high-temperature tempering, finishing machining and quality control. To form a coating on 30KhGSA steel, an installation for plasma surfacing of bodies of rotation is used. A method and surfacing materials for multilayer plasma surfacing are developed, which make it possible to obtain deposited layers made of high-speed alloys (type R18Yu), additionally alloyed with nitride ferrochrome and titanium, which allows increasing the nitrogen content from 0.02 to 0.12 %. The surfacing method with low-temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. The hardness of the deposited metal after high-temperature tempering at a temperature of 560...580 °C increases to 62...64 HRC. Multilayer plasma surfacing made it possible to obtain a high-quality surfaced layer without cracks, pores and microstructure defects. The main phases of the deposited layer are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium. The wear resistance of the deposited parts of metallurgical equipment (rolls and rollers of crushers) increases by 1.5—2.0 times.

Efficiency of the Action of Plasma Flows on the Surface of 30KhGSA Steel during the Deposition of Electric Arc Vacuum Ion–Plasma Coatings

Efficiency of the Action of Plasma Flows on the Surface of 30KhGSA Steel during the Deposition of Electric Arc Vacuum Ion–Plasma Coatings

Study of acoustic emission signals generated by crack growth during crack resistance testing of steel specimens

The results of crack resistance tests of specimens made of 30KhGSA steel using the acoustic emission method are presented. The obtained set of characteristics can serve as the basis for the development of technical diagnostics methods of steel pressure cylinders.

Optimization of Parameters of Friction Stir Welded Unlike Joints of Medium-Carbon Alloy Steels 30KhGSA and 40KhMFA

Optimization of Parameters of Friction Stir Welded Unlike Joints of Medium-Carbon Alloy Steels 30KhGSA and 40KhMFA

Effects of spring action of a non-rigid body stamped from 30KhGSA steel sheet on the accuracy of machining

The high mechanical properties of 30KhGSA steel create a spring action effect when a non-rigid box-shaped body is fixed in a machine fixture. Comparisons are made between the results of mathematical simulation of elastic deformations of the base wall of a non-rigid box-shaped body when fixed in a fixture for machining and statistical processing of the results of an experimental study of changes in the dimensions obtained during machining, specified from the base wall of the body, under comparable conditions. The mathematical simulation of elastic deformations of the base wall of a non-rigid box-shaped hull under given conditions and assumptions showed that the displacement curve of the base wall of the body with a concave bottom at a measurement height of more than 50 % of the body height implies displacements approximately two times greater than for the displacement curve of the base wall of the body with a convex bottom. To assess the accuracy of fulfilling the dimensions specified from the base wall of the body, two test batches of non-rigid box-shaped housings were made in an amount of 10 pieces. Bodies with non-flatness of the base surface in the form of concavities were selected in the first batch, in the form of convexities in the second batch. Dimensional measurements were made at a height of 75 % from the bottom of the box body, as the closest to the maximum height values in the mathematical experiment. Statistically significant coefficients are found in the equations of regression of the errors in the dimensions x, y, z from the concavity of the base surface EFK of the bottom of a non-rigid box-shaped body. Regression coefficients for given sizes are ambiguous for bodies with a concave and convex bottom. Such a difference in the experiment can be explained by the presence of local shape errors on some workpieces. For one size there is a tenfold ratio of coefficients; at the same time, for another size in the equations, this ratio is close to unity. Such a difference in the experiment can be explained by the presence of local shape errors on some workpieces.

Influence of the heating force in rotational friction welding on mechanical properties and tensile fracture mechanism of dissimilar welded joints of 30KhGSA and 40KhMFA steels

This article presents the results of evaluating the effect of heating force, as one of the parameters of rotational friction welding, on the mechanical properties and mechanism of tensile failure of dissimilar welded joints of medium-carbon steels 30KhGSA and 40KhMFA. The results of studies of the microstructure and microhardness of welded joints are presented. The fracture mechanism of welded specimens during tensile testing was evaluated on the basis of strain distribution maps obtained by the digital image correlation method and the results of fractographic analysis. The features of the development of deformation and failure of welded joints obtained at different heating forces are shown. From the point of view of the equal strength of the structure with a welded joint the optimal values of this parameter of rotary friction welding for joining steels 30KhGSA and 40KhMFA are recommended.The reported study was funded by RFBR according to the research project № 20-38-90032.When conducting mechanical tensile tests and studying the distribution of deformation fields, equipment was used that is part of the Plastometriya collective centre of the IES named after E. S. Gorkunova of the Ural branch of the RAS

Study of Resistivity Distribution in Modified Surface Steel

This work focuses on making and studying steel conductors with inhomogeneous surface conductivity. Employing such materials (structures) for engineering the high-field pulsed magnets can provide them with enhanced durability. In this work, monotonically changing resistivity was realized by pack chromizing the medium-carbon steels, 30KhGSA and 40Kh, which were treated at 1000 °C in argon for 150 h under the Cr-load of 20 mg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> to obtain a diffuse layer with minimal carbides at the surface. An approach to investigate the resistivity distribution across a diffuse layer after steel chromizing is suggested and involves a stepwise surface grinding, resistance measurement, and analytical processing of experimental data. The resistivity profile obtained by this method is well described by the complementary error function. At the near-surface layer, 30KhGSA and 40Kh steels have almost the same values of resistivity, about 110– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$115 ~\mu $ </tex-math></inline-formula> Ohm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> cm, which is 2.9–4.3 times higher than that in the bulk depending on steel. A strong correlation, almost a linear dependence, of resistivity with the depth-derived chromium concentration in the material was found. The proposed method allows one to measure the depth-varied resistivity for ferrous alloys with proper accuracy, while it does not require complex measuring equipment compared with other ones.

Raising the Properties of Steel 30KhGSA by Creating a Mixed Martensitic-Austenitic Structure

Raising the Properties of Steel 30KhGSA by Creating a Mixed Martensitic-Austenitic Structure

Influence of Forging Force on Tensile Strength of the 30KhGSA/40KhMFA Steels Welded Joints Made by Rotary Friction Welding

This paper presents studies of welded joints of steels 30KhGSA and 40KhMFA made by rotary friction welding. The influence of the forging force on the microstructure and tensile properties of standard specimens and specimens with a notch in the contact zone is analyzed. The results of measuring the microhardness and fractogram of the fracture surface are presented. It has been established that in the selected range of forging forces, the strength of the contact zone is higher than other sections of the thermomechanical affected zone and the base metal of the materials to be welded. In this case, the maximum strength of the contact zone occurs at lower values ​​of the forging force due to the formation of common grains along the contact line as a result of the process of mutual volumetric recrystallization.

Experimental and Theoretical Study of high-velocity penetration of long rod projectiles into sand

Results of computations with the use of improved modified Alekseevskii-Tate theory (IMATT) are compared to experimental data on high-velocity penetration of long rod projectiles into sand in the impact velocity range of V_0=0.5-3.5 km/s. Projectiles were made of three different metals: M1 copper, WNZh tungsten heavy alloy and 30KhGSA steel. The value of hardening coefficient k in the linear dependence of the projectile material yield on pressure could be determined using IMATT and experimental data on dependence of differential penetration coefficient K on the penetration velocity. At penetration in regime of the hydrodynamic erosion of projectile, differential penetration coefficient K could be approximated just by dependence on the ratio of the impact velocity of penetration to the value of the critical velocity, above which the projectile deforms plastically during penetration. The values of the critical velocity may differ for specific projectile material properties as well as the density and the humidity of sand. Keywords: high-velocity penetration, plastic deforming, yield, hydrodynamic erosion, Alekseevskii-Tate theory, experiment.