Steel Kh12M Research Articles

Experimental study of the process of laser treatment of steel Kh12M

Experimental study of the process of laser treatment of steel Kh12M

Influence of heat treatment on the microstructure of steel coils of a heating tube furnace

Transportation and refining of heavy metal-bearing oil are associated with the problems of localized destruction of metal structures and elements due to corrosion. In the process of equipment operation, it was revealed that premature failure of steel coils of heating tube furnaces at oil refineries and petrochemical plants was associated with insufficient strength and corrosion resistance of the steelwork. The study of the effect that structure and phase composition of 15KH5M-alloy steel elements of heating furnaces at oil refineries have on the corrosion properties, associated with mass loss and localized destructions in the process of heat treatment, allows to develop protective measures and determine heating modes with a rate-limiting step of oxidation. The rate of various corrosion types of 15KH5M steel is used as an indicator to assess the effectiveness of the applied modes of coil heat treatment in order to increase their corrosion resistance and improve their operational characteristics. Conducted experiments on heat treatment of certain steel coil sections allowed to determine rational heating modes for the studied coils, which made it possible to reduce their mass loss and increase corrosion resistance of working surfaces in the process of operation. Proposed heat treatment of steel coils at specified intervals of their operation in the tube furnaces creates conditions for their stable performance and affects the degree of industrial and environmental safety, as well as reduces material costs associated with the repair and replacement of individual assemblies and parts of tube furnaces.

Study of Structural and Mechanical Heterogeneity through Steel 15Kh5M Carburized Pipe Wall Thickness

Features of the change in chemical and phase composition, structure, strength, ductility, and impact strength of steel 15Kh5M pipe material used for furnace coils of catalytic reforming units after carburizing the external and internal surfaces are studied.

Study of the structural degradation of steel 15Kh5M upon continuous duty

Structural degradation of the material upon long-term thermal and force impacts is a complex process which includes migration of the grain boundaries, diffusion of the active elements of the external and technological environment, hydrogen embrittlement, aging, grain boundary corrosion and other mechanisms. Application of the fractal and multifractal formalism to the description of microstructures opens up wide opportunities for quantitative assessment of the structural arrangement of the material, clarifies and reveals new aspects of the known mechanisms of structural transformations. Multifractal parameterization allows us to study the processes of structural degradation from the images of microstructures and identify structural changes that are hardly distinguishable visually. Any quantitative structural indicator can be used to calculate the multifractal spectra of the microstructure, but the most preferable is that provides the maximum range of variation in the numerical values of the multifractal components. The results of studying structural degradation of steel 15Kh5M upon continuous duty are presented. It is shown that structural degradation of steel during operation under high temperatures and stresses is accompanied by enlargement of the microstructural objects, broadening of the grain boundaries and allocation of the dispersed particles which are represented as point objects in the images. The processes of structural degradation lead to an increase in the range of changes in the components of the multifractal spectra. High values of complex indicators of structural arrangement indicate to an increase in heterogeneity and randomness at the micro-scale level, but at the same time, to manifestation of the ordered combinations of individual submicrostructures. Those structural transformations adapt the material to external impacts and provide the highest reliability and fracture resistance of the material.

Optimization of the Laser Hardening of Punching Tools

Optimal conditions for laser hardening of punching tools made of a steel Kh12M are selected. Leading edges should be hardened under surface micromelting conditions. A laser fused layer should be ground after the treatment, controlling the metal removal thickness. Tests demonstrated a 2–4 increase in the service life of punching dies after laser thermal treatment.

Contact Wear of Steels Kh12M and R6M5

Comparative analysis of results of contact wear of steels Kh12M and R6M5 is performed with allowance for the structural evolution detected in experimental studies and by computer modeling. It is shown that metal matrix properties determine steel resistance to contact wear and the structural changes arising during wear.

Using friction welding for producing heat exchanger equipment from martensitic 15Kh5M steel

The results of mechanical and other types of tests of metal of welded joints in pipe blanks of 15Kh5M martensitic steel, produced by friction welding with rotation, are presented. On the basis of the analysis of the test results it is concluded that 15Kh5M can be efficiently welded by friction welding and that the method can also be used for producing the tube–tube plate sections of heat exchangers made of 15Kh5M steel with appropriate modernization of welding equipment.

Spark alloying of an AL9 alloy by hard alloys

The phase compositions of spark coatings of Kh12M steel with a VT1-0 (titanium) alloy and T15K6 and T30K4 hard alloys are studied. It is shown that the TiC titanium carbide forms in all cases and tungsten carbide decomposes with the formation of tungsten in a coating. These processes are intensified by increasing time, capacitance, and frequency. The surface hardness, the sample weight, and the white layer thickness increase monotonically.

Quantitative Evaluation of Steel 15Kh5M Structural Degradation in a Stressed State and with Thermal Exposure

A procedure is proposed for quantitative evaluation of steel 15Kh5M structural degradation with high temperature and static stresses, determined by means of computer metallography. Quantitative indices are provided for steel 15Kh5M microstructure corresponding to the limiting stage of structural degradation, on whose basis it is possible to predict the operating life of oil refining equipment.

Study of the Structure and Mechanical Properties of a Weld in a Heat Exchanger by Computer Modeling

This article examines the effect of the welding of steel 15Kh5M on the formation of local thermal stresses in a weld formed between a tube and the tube array of a shell-and-tube heat exchanger. The study was performed by computer modeling of the welding operation with the use of the finite-elements method.

Effect of inoculation, microalloying and heat treatment on corrosion resistance and mechanical properties of steel 15Kh5M

The effect of inoculation, microalloying and heat treatment on the mechanical properties and on the resistance of steel 15Kh5M to carbon-dioxide corrosion and stress corrosion cracking is determined. Comparative analysis of the morphology and composition of products of carbon-dioxide corrosion formed on steel 15Kh5MFBCh under laboratory and field conditions is performed.

Effect of frictional heating on the surface-layer structure and tribological properties of titanium nickelide

The effect of frictional heating (whose intensity was varied at the expense of changes in the sliding velocity from 0.35 to 9.00 m/s) on the rate of wear, friction coefficient, friction thermopower, structure, and microhardness of the Ti49.4Ni50.6 alloy in a microcrystalline (MC) state with grains 20–30 μm in size and in a submicrocrystalline (SMC) state with grains 300 nm in size has been investigated. The tribological tests were conducted under the conditions of dry sliding friction in air using the finger-disk (made of steel Kh12M, hardness HRC = 63) scheme at a normal load of 98 N. Due to the frictional heating, the temperature in the surface layer 0.5 mm thick of the samples changed from 150–200 (at a sliding velocity of 0.35 m/s) to 1100°C (at a velocity of 9 m/s). The alloy structure has been studied with the help of metallographic and electronmicroscopic (scanning and transmission microscopy) methods. It has been shown that the rate of wear of the titanium nickelide in the MC and SMC structural states is more than an order of magnitude lower than in the 12Kh18N9 steel and several times less than in the 40Kh13 steel. The fracture of the friction surface of the titanium nickelide occurs predominantly by the fatigue or oxidation-fatigue mechanisms, which are characterized by a relatively low wear rate, whereas the 40Kh13 and 12Kh18N9 steels show a tendency to intense thermal adhesive wear (seizure) at velocities higher than 0.35 m/s. It has been shown by the electron-microscopic investigation that nanocrystalline structures consisting of crystals of the B2 phase, oxides of the TiO2 type, and some amount of martensite B19′ are formed in the process of friction in the surface layer of the titanium nickelide. It has been concluded that an enhanced wear resistance of the titanium nickelide is caused by the high heat resistance (strength) and high fracture toughness of the nanocrystalline B2 phase and by the presence of high-strength thermostable oxides of the TiO2 type formed upon friction.

Tubing with high corrosion resistance

The optimum chemical composition and the regime for heat treatment of heat-resistant steel 15Kh5M are determined for the production of tubing with strength of group L80 (API 5CT) and high cold resistance and resistance to carbon dioxide and sulfurated hydrogen corrosion at low alloying additives of chromium and molybdenum.

Effect of Initial Microstructure of Tool Steels on the Thickness and Hardness of Layers Obtained by Nitrocarburizing

The effect of preliminary heat treatment on the microstructure and kinetics of formation of the hardened layer in the process of subsequent nitrocarburizing of steels A681 (ASTM), Kh12M (GOST), Kh12FS (GOST), 6437E (AMS), and X46Cr13 (BS) is studied. Preliminary treatment of two kinds, i.e., annealing and quenching with tempering, is considered. The thermochemical processes are performed in a solid carburizer (powder) at 500°C for 4 h. The thickness, hardness, microstructure, and phase composition of the resulting layers are determined.

Improving the Quality of Dies from Steel Kh12M

The effect of heat treatment modes and cold treatment on the quality of dies from steel Kh12M is studied. A new mode of heat treatment involving cold treatment at – 100°C is suggested. Comparative tests of dies produced by standard and suggested methods are described for the case of embossing of a copper collector for starters. It is shown that the quality of dies treated by the new method is higher and their life increases by a factor of 2 – 2.5.

Studying the Resistance of 15Kh5M Steel to a Technological Medium

Studying the Resistance of 15Kh5M Steel to a Technological Medium

Effect of the quenching technique on the structure of steel Kh12M

Results of a study of the structure and phase composition of steel Kh12M after quenching by various regimes are presented. It is shown that the favorable combination of mechanical and service properties of steel Kh12M attained after a two-stage quenching is caused by the presence of finely disperse special carbides uniformly distributed in the matrix.

Two-stage quenching of steel Kh12M

1. Two-stage quenching (with subsequent tempering) provides an increase in the impact toughness, bending strength, and hardness of steel Kh12M compared to single-stage quenching, and especially to standard quenching in oil. Use of two-stage quenching and tempering instead of the standard heat treatment increases the hardness of the steel by 0.5HRCe and doubles the impact toughness and the bending strength. 2. The optimum combination of properties of steel Kh12M (within the study performed) has been provided by two-stage quenching by a regime of 1030°C→250°C 5 min →560°C 60 min. 3. Two-stage quenching by the latter regime increases the tempering resistance of steel Kh12M by suppressing the processes of segregation and coagulation of cementite-type carbides in the range of tempering temperatures of 200–350°C. 4. Two-stage quenching of steel Kh12M has been shown to double the service life of dies relative to the standard heat treatment.

Structure formation in laser carboborochromizing of steel Kh12M

Investigation of the processes of structure formation in laser alloying of steels and alloys is important. Surface strengthening of low- and intermediate-alloy steels by laser alloying with the use of multi-component paste coatings is of special interest.

Technology of welding of products made of steel 15Kh5M with control of thermal cycles

Technology of welding of products made of steel 15Kh5M with control of thermal cycles