Chromium-nickel Steels Research Articles

Effect of Implantation of Argon and Oxygen Ions on the Physicochemical Properties and Corrosion and Electrochemical Behavior of 14Cr17Ni2 Chromium–Nickel Steel

Effect of Implantation of Argon and Oxygen Ions on the Physicochemical Properties and Corrosion and Electrochemical Behavior of 14Cr17Ni2 Chromium–Nickel Steel

Impact of Nitrocarburizing on Hardening of Reciprocating Compressor’s Valves

One of the urgent problems in reciprocating machinery is ensuring the functional properties of direct-flow valves. Coatings of these parts should increase energy efficiency, reduce compressed gas temperature, and increase compressor performance. In this article, the effect of nitrocarburizing in pastes on increasing the performance and resource of such valves was studied. The primary research methods were metallographic and electron-metallographic research of the surface layer structure of steel 60Si2Cr. Comparison with similar characteristics obtained for stainless steel 09Cr15Ni8Al was also performed. As a result, it was determined that nitrocarburizing of carbon spring steel 60Si2Cr leads to a greater depth of the diffusion layer than nitrocarburizing of alloyed chromium-nickel steel 09Cr15Ni8Al. Simultaneously, the diffusion layers of both types of steel are almost the same. Simultaneously, the increase in the endurance limit of 60Si2Cr steel during nitrocarburizing is about 1.3 times compared to untreated material. Finally, the predictive maintenance showed that the evaluated lifetime of nitrocarburized valves increases by 5.7 times compared with untreated valves.

Formation and Destruction of Oxide Films during High-Speed Anodic Dissolution of Chromium-Nickel Steels in Electrolytes for Their Electrochemical Dimensional Machining

It is shown that at high-speed pulsed galvanostatic anodic dissolution of chromium-nickel steels Kh3N35VT (CSN17335), Kh18N10 (AIS1 304) in the regions of pulse durations of 20–2000 ms and current densities of 1–100 A/cm2 in electrolytes for their electrochemical dimensional machining (ECDM) (chloride, nitrate, and mixed chloride-nitrate with an electrical conductivity of 0.15 S/cm), a significant part of the charge (up to 50%) is spent on the formation of a passivating oxide film having a semiconductor character. As a result, the film, not the alloy, is subject to electrochemical treatment. As a result, the current output of the ECDM process of these materials under pulsed conditions is ~ 50–70%, depending on the composition of the alloy. The speed of the process increases with the transition to a constant processing current because of the destruction of the film due to its thermokinetic instability (“thermal explosion”) caused by an increase in the surface temperature.

Use of Non-Vacuum Electron Beam Cladding for Creating a Combined Joint of High-Carbon and Chromium-Nickel Steels

Use of Non-Vacuum Electron Beam Cladding for Creating a Combined Joint of High-Carbon and Chromium-Nickel Steels

Structural Transformations in Cold-Rolled Austenitic Chromium-Nickel Steel Studied by Synchrotron X-Ray Diffraction and Peak Profile Analysis

Structural Transformations in Cold-Rolled Austenitic Chromium-Nickel Steel Studied by Synchrotron X-Ray Diffraction and Peak Profile Analysis

Mechanical Properties Degradation Modeling of Austenitic Chromium-Nickel AISI 304 Steel After Thermal Ageing

Austenitic chromium-nickel steel AISI 304 is used as a structural material for heat exchange equipment. Long-term operations result in degradation of mechanical properties of material due to formation of chromium carbides at grain boundaries. The influence of various thermal ageing modes of AISI 304 steel on mechanical properties with metal fragments of reactor plant on fast neutrons of RP BN-600 taken as an example after long-term operation has been investigated.

Estimation of glass lubricant viscosity for hot extrusion of Cr-Ni steel and Ni alloy tubes

Purpose. Estimation of optimal viscosity of a glass lubricant for chromium-nickel steel tube extrusion depending on the deformation resistance, chemical composition of metal and the temperature, degree and rate of deformation. Methodology. To determine the force conditions for tube extrusion, a complex factor of deformation resistance was used, which consists in estimating the value of deformation resistance under the basic process parameters of extrusion plants and its refinement depending on the deviations of heating temperature and wall thickness of billets as well as the degree and rate of deformation from the base conditions. Findings. The dependence of basic values of deformation resistance on the percentage of alloying elements (Ni + Cr) in steels has been found. With the addition of hardening alloying elements (Mo, W, V, Nb) into the alloy steel, its deformation resistance increases in proportion to their percentage. Analytical expressions for calculating the base values of deformation resistance for different extrusion plants have been obtained. Originality. For the first time, the principles governing estimation of the optimal viscosity of glass lubricants based on the chemical composition of steel to be formed, its temperature and the degree and rate of deformation of the blank, thickness of the lubricating layer and geometric dimensions of the tool (die) in hot extrusion of tubes have been established. Practical value. The use of the results of calculation according to the developed method will make it possible to increase the surface quality of tubes manufactured by extrusion and reduce the volume of their subsequent machining.

Повышение коррозионной стойкости шлифованных деталей рациональным применением энергии ультразвукового поля

The results of experimental studies of the effect of processing conditions on the corrosion resistance of ground parts made of stainless chromium-nickel steel of austenitic class 12X18N9T2 are quoted. It is found that the introduction of ultrasonic field energy into the zone of generation of geometry during grinding makes it possible to increase the corrosion resistance of parts by 12...15%, depending on the grinding mode.

Improving the Corrosion Resistance of Polished Stainless Steel Parts by Introducing the Energy of the Ultrasonic Field into the Forming Zone

This article presents the results of experimental studies of the effect of processing conditions on the corrosion resistance of polished parts made of stainless chromium-nickel steel of austenite class 12X18N10T. It is established that the introduction of the ultrasonic field energy into the shaping zone during grinding can increase the corrosion resistance of parts by 12-15 %, depending on the elements of the grinding mode. The latter is explained by a significantly lower heat-force stress during processing, which, in turn, leads to a decrease in the magnitude and depth of distribution of technological residual tensile stresses along the surface layer.

Improving safety during operation of gas turbine units

This article considers the possibility of improving the safety during operation of gas turbine plants due to improving the strength characteristics of rotor blades, by using ultra-finegrained ferrite-martensitic steel of the EI-961 class for their manufacture. It is known that one of the main elements of stationary gas turbine plants is rotor blades made of EI-961 steel, which is a typical representative of ferrite-martensitic steels. Due to the fact that the blade complex determines the safety and service life of gas turbine plants, improving the strength characteristics of ferrite-martensitic stainless steels, it is important and relevant to increase the reliable and safe operation of such plants. As a result, studies have been carried out using EI-961 - stainless heat-resistant high-alloy martensitic-grade chromium-nickel steel as the starting material. To form an ultrafine structure, the samples were subjected to intense plastic deformation followed by heat treatment. It was revealed that the use of intense plastic deformation by torsion and equivocal angular pressing led to a significant increase in the microhardness of steel EI-961, which in turn leads to an increase in strength characteristics. To evaluate the mechanical properties, tensile tests of standard samples were carried out, which showed that additional re-hardening of samples after standard thermal treatment of martensitic steel EI-961 led to an increase in strength, it is clear that in an ultrafine state, the strength gain is greater than in coarse-grained (in an ultrafine state - 30%, coarse-grained - 11%), while maintaining ductility 5%.

Mechanical Behavior of Armor Steel Gas Metal Arc Welding Joints Performed by Nickel-Chromium and Low-Alloy Steel Filler Metals

Mechanical Behavior of Armor Steel Gas Metal Arc Welding Joints Performed by Nickel-Chromium and Low-Alloy Steel Filler Metals

Разработка технологии тонкослойного лазерного модифицирования хромоникелевой стали 12Х18Н10Т

Разработка технологии тонкослойного лазерного модифицирования хромоникелевой стали 12Х18Н10Т

Durability Aspects of Chloride-Affected Cracked Concrete Structures Reinforced with 1.4003 Rebars

The protection of reinforced concrete components exposed to chlorides is often ensured by coating systems, which are usually associated with high maintenance costs over the service life. A possible alternative is the use of high-alloy, stainless steel reinforcement. Through smart selection in areas subject to particularly high stresses and the possibility of using mixed reinforcement with black steel, this type of reinforcement can also be used for economical construction. In many areas, it is sufficient to use significantly cheaper chromium steel rebars instead of very expensive, highly corrosion-resistant austenitic chromium-nickel steels. An industrial research project was carried out at Munich University of Applied Sciences in which the resistance of a chromium steel reinforcement with material number 1.4003 in chloride-exposed separation cracks of RC-specimens was investigated. The results obtained formed the basis for the development of design variants for underground parking garages. Structural tests on a large number of existing structures show how a long service life can be achieved with such reinforcement even under high chloride loads.

HIGH-SPEED ANODIC DISSOLUTION OF CHROMIUM-NICKEL STEEL IN A NITRATE SOLUTION WITH THERMOKINETIC INSTABILITY OF THE OXIDE FILM

It is shown that high-speed anodic dissolution of Kh18Ni10 chromium-nickel steel (Cr18Ni10) in a concentrated nitrate solution occurs through an anode oxide film (AOP), the for-mation of which is carried out as a result of charge transfer, and the dissolution is chemically. The condition of constant film thickness is achieved due to the equality of the rates of these two pro-cesses (electrochemical formation of the film and its chemical dissolution) and is realized under pulsed conditions until the boiling point of the electrolyte is reached at the film-solution interface. When thermokinetic instability of the anodic oxide film occurs at the film-solution interface at surface temperatures exceeding the boiling point of the electrolyte, the interaction of the dissolving surface of the alloy free of the film with the solution (electrolyte) is observed. The dissolution rate in this case may exceed the Faraday rate (anomalous anodic dissolution) as a result of the destruc-tion of the film, for the formation of which the leaked charge was spent. The presence of a barrier film at the metal-film interface is the reason that the change in the surface temperature and disso-lution rate is achieved only by changing the heat transfer conditions of the metal surface.The porous part of the film in contact with the solution is a “heat seal” (limits the heat removal towards the electrolyte), as a result of which a change in the electrolyte flow rate does not affect the surface temperature. Based on the results of calculating heat fluxes, the influence of the temperature of the metal surface in contact with air (the outer part of the surface of the dissolving metal) on the heat transfer coefficient during natural convection and rotation at a speed of 1000 rpm of the elec-trode was estimated, as well as the ratio of the corresponding heat fluxes. An increase in convective heat removal during rotation leads to a decrease in temperature in the anode treatment zone and, as a consequence, to a decrease in the dissolution rate.

Adsorption of the IFKhAN-92 Inhibitor on Chromium–Nickel Steel from Mineral Acid Solutions

Adsorption of the IFKhAN-92 Inhibitor on Chromium–Nickel Steel from Mineral Acid Solutions

Wear Analysis of Forging Tools Used in an Industrial Production Process—Hot Forging in Closed Dies of the “Head-Disk” of an Engine Valve Forging

The article performs an analysis of the durability of punches applied in the process of producing a valve forging from chromium-nickel steel. A forging of this type is made in two operations: coextrusion of a long shank, followed by finishing forging in closed dies of the valve head. The product obtained in this way (after other additional finishing procedures) constitutes the key element of the combustion engine (resistant to high pressures and temperatures) in motor trucks. Unfortunately, a significant problem in this production process is a relatively low durability of the forging tools, especially the punch used in the second forging operation. The key element at this stage, deciding about the punch’s further operation, is the area of the so-called “calotte”. The short-term life of the tools results from very hard performance conditions present during the forging process (periodical high mechanical and thermal loads, long path of friction). The latter cause intensive abrasive wear as well as high adhesion of the forging material to the tool surface. Based on the performed studies, including the following: technology analysis, numerical modelling, macro analyses combined with 3D scanning of tool sections as well as microstructural tests and hardness measurements, it was established that it is crucial to properly select the process parameters (charge and tool temperature, tribological conditions), as even slight changes introduced into them significantly affect the operation time of the forging tools. Mastering and proper implementation of the analyzed forging technology requires numerous further studies and tests, which will enable its perfection and thus increase the durability of the tools as well as the quality of the produced items.

Investigation of the Structural, Mechanical and Tribological Properties of Plasma Electrolytic Hardened Chromium-Nickel Steel

This paper investigates how electrolytic plasma hardening (PEH) bears upon the changes in the phase structural and tribological properties of steel 0.34C-1Cr-1Ni-1Mo-Fe, which is widely used in manufacturing highly stressed gears. The samples of steel 0.34C-1Cr-1Ni-1Mo-Fe went through the PEH in an electrolyte containing an aqua solution of 20% calcined soda (Na2CO3) and 10% carbamide ((NH2)2CO). The initial steel 0.34C-1Cr-1Ni-1Mo-Fe is stated to have the following structural components: a lamellar pearlite with volume share of 35%, a ferrite-carbide mixture of ~45% and a fragmented ferrite of ~20%; after the PEH it contains lath-lamellar martensite, fine particles of cementite and M23C6 carbide. The durability of steel 0.34C-1Cr-1Ni-1Mo-Fe was found to rise by 3.4 times after the PEH and its microhardness increased in 2.6 times. The curve-tension of the crystal lattice was established to be like plastic (χ = χpl) and does not cause the formation of microcracks in the material.

Mechanisms of Stress Corrosion Cracking of Irradiated Austenitic Chromium–Nickel Steels Used for WWER and PWR Vessel Internals

Mechanisms of Stress Corrosion Cracking of Irradiated Austenitic Chromium–Nickel Steels Used for WWER and PWR Vessel Internals

Influence of titanium and zirconium on structure and heat-resistance of low-carbon iron-aluminium alloys

The paper considers the effect of introducing ferroalloys containing titanium and zirconium on the structure and heat-resistance of low-carbon ferroalloys. Theoretically and experimentally, it has been proven that addition of 1.0 mass. % of titanium and 0.1 mass. % of zirconium to a low-carbon iron-aluminum melt containing 12 – 14 mass. % of aluminum, grinds its structure increasing temporary resistance and heat-melting. Titanium and zirconium are strong carbide-forming elements. When introduced into a low-carbon iron-aluminium alloy, they form a large number of crystallization centers, thus affecting its microstructure, allowing to get shredded and more equal grain compared to an alloy without additive. This in turn increases the strength limit of processed alloy. In addition, the use of titanium as a modifying additive in a low-carbon ferroalloy allows increasing its heatresistance, which exceeds several times the heat-resistance of famous chrome-nickel steel of 20Kh23N18 grade. As a result, a new technology for obtaining titanium and zirconium was developed based on research of the effect of their modifying additives on the structure and heat-resistance of low-carbon iron-aluminum alloys.

STUDY OF CHANGE IN WEAR RESISTANCE OF STAINLESS STEEL SURFACE OBTAINED BY LASER PULSE ALLOYING IN THE COATING LAYER

The paper describes an experimental study of laser pulsed modification of the surface of stainless chromium-nickel steel of the austenitic class 12Cr18Ni10T with a graphite coating previously applied to it. The microhardness of the treated surface and its dependence on the modes of laser radiation were determined. The abrasion method was used to study the change in the wear resistance of the modified layer and the possibility of its increase. For a quantitative assessment of the surface resistance to wear, a gravimetric analysis of samples subjected to ball abrasion was carried out, the results of which are fully consistent with the calculation of the dimensionless wear resistance index. It was found that the value of the microhardness is largely influenced by the voltage of the pulses. Thus, the highest microhardness indicators were observed during processing by laser pulses in the voltage ranges of 250-280 V and 340-440 V and take values of 5-6 GPa and 4-5 GPa, respectively. A comprehensive study of abrasion resistance, including the calculation of a dimensionless wear resistance index and an analysis of the weight loss of steel samples as a result of the test, showed that, to the greatest extent, the surface hardening effect is characteristic of samples subjected to treatment with laser pulses focused into a spot 1 mm in diameter at a pulse voltage of range 300-400 V.