Steel 10KhSND Research Articles

ANALYSIS OF THE DEVELOPMENT OF GONDOLA CAR BODY STRUCTURES

The article is devoted to the analysis of promising directions for the development of gondola car body structures. It considers the history of the emergence of gondola cars as a separate type of railway rolling stock. The authors systemise the design of gondola cars and discuss the advantages and disadvantages of various designs. The study has shown that the manufacture of the two-axle gondola cars began in the second half of the 19th century. They were designed mainly for transporting coal and iron ore, with their bodies made of wood. Further design improvement led to the appearance of four-axle gondola cars with increased load capacity. Rolled metal began to be used in body structures to improve strength. Particular attention in the article goes to analysing the results of innovative design and technological solutions intended to enhance the efficiency and reliability of body structures. The research indicates that attempts to replace steel with aluminium alloys in manufacturing bodies did not yield results. The reason is the high cost of aluminium and the labour-intensive manufacturing. A promising direction is the use of low-alloy steels 10KhSND and 10KhNDP. For many years, there has been a trend in the railcar-building industry toward producing higher-load gondola cars. It requires increasing the axle load to 25 tons. However, implementing such cars necessitates a substantial restructuring of the railway infrastructure. We consider the design features of innovative domestic gondola cars in detail. The latest technical solutions for the body frame, efficient materials, and components with improved performance have doubled the overhaul mileage. The article analyses the North American experience of gondola car construction and operation. It shows that some models of American gondola cars use longitudinal cylindrical boxes to increase the body volume and reduce the car’s centre of mass. They are on both sides of the girder beam and occupy the space between the carts. Aluminium alloys are also widely used: the frame and lower part of the body are steel, and the side and end walls are aluminium alloy. Keywords: gondola car, body, girder beam, pivot beam, side walls, hatch cover, reliability.

Study of the effect of static stresses on the hydrogen content and electrochemical characteristics of steels of different types

When cathodic protection is applied in places where paint films are damaged, an intense release of hydrogen occurs, which is removed both through diffusion and by transition from the adsorbed state on the metal surface to the subsurface layers thus leading to static hydrogen fatigue of steels, i.e., a brittle fracture occurs suddenly under static loading conditions at stress values significantly lower than the strength limit and even below the plasticity limit. We present the results of studying the impact of static tensile stresses on the hydrogen absorption by a metal during its cathodic polarization and the distribution of hydrogen over the cross-section of the metal surface. Three types of metal samples were used: wire samples made of U8A steel, plate samples made of 10KhSND steel, and semicircular samples made of Kh18N9T stainless steel with a stress concentrator. Tests of wire and semi-ring samples were carried out under a constant load and plate samples were tested under constant deformation. Polarization of wire and plate samples was carried out at different current densities for 4 days and semi-ring samples for 1 hour. At the end of polarization, the layer-by-layer distribution of hydrogen absorbed by the metal was determined by the anodic dissolution method. It is shown that with increasing deformation, the hydrogen content of the surface layers of the metal increases. Moreover, application of tensile loads and deformation of the metal by bending contribute to an increase in the amount of absorbed hydrogen and affect hydrogen distribution over the metal cross section. The thickness of the layer containing the maximum amount of hydrogen differs in steels of different compositions and structures. The results obtained can be used to protect structural steels against corrosion in sea water.

Influence of calcium consumption and content on the quality of 10KhSND steel made from continuously cast slabs

The effect of calcium consumption during out-of-furnace processing and its content in the finished metal on the quality of sheet steel grade 10KhSND, obtained from continuously cast slabs, has been studied. The research is based on the results of evaluating the macrostructure of slabs obtained from a continuously cast billet, as well as after testing the finished metal to determine impact strength, contamination with non-metallic inclusions, and ductile-brittle transition temperature. The paper analyzes the effect of consumption and calcium content in the metal.

The Metallurgical hydrogen as an indicator and cause of damage to rolled steel: Hydrogen diagnostics of fracture

Fatigue tests and measurements of the volumetric distribution of metallurgical hydrogen in specimens cut from rolled I-beam 60Sh3 made of steel 10KhSND were carried out. Fatigue tests show a 20% reduction in fatigue limits compared to similar sheet material. On the fractures of the samples, there are flock-like defects in the areas of interface of the flanges of the I-beam, or the so-called zones of difficult deformation. The concentration of metallurgical hydrogen is unevenly distributed and varies from 0.17 ppm to 1.8 ppm. Large concentrations of hydrogen are observed in the zones of difficult deformation, which indicates the hydrogen nature of the metal defects observed at the fracture. The result of mechanical tests and hydrogen diagnostics is a manufacturing defect of rolled products that cannot be corrected. Hydrogen diagnostics using metallurgical hydrogen (without hydrogen charging samples) takes tens of times less time than mechanical tests, and gives an adequate result.

Silicon in steels of various structural classes as element that influences their properties when operating in high temperature range. Part 1. Heat embrittlement

The study of the effect of silicon on the strength properties of steels of different structural classes is carried out. Modern methods of analysis are used — neural network prediction of mechanical characteristics both in the initial state and with long exposure up to 10 000 hours-cycles. For a sample of industrial melting from steel 10KhSND, a fractographic analysis of the fracture is carried out in order to determine the location of silicon and its role in the thermal embrittlement of steel is determined by constructing a computerized supermodel of the fracture.

Formation of Dispersed Acicular Ferrite in the Structure of Cold-Resistant Welds at Temperatures down to –70°C during Manual Arc Welding at the Assembly of Metal Structures Made of 10KhSND Steel: Part 1

Formation of Dispersed Acicular Ferrite in the Structure of Cold-Resistant Welds at Temperatures down to –70°C during Manual Arc Welding at the Assembly of Metal Structures Made of 10KhSND Steel: Part 1

USE OF FACTOR ANALYSIS METHODS IN THE STUDY OF THE STRUCTURAL STATE OF THE WELDED JOINT AFTER LASER WELDING

Formulation of the problem. The use of the mathematical apparatus of factor analysis allows us to investigate the stability of correlations between individual variables. It is the correlations between the variables themselves, as well as between the variables and the selected factors that contain the basic information about the stage of development. The results of factor analysis will be informative if they can be interpreted from the point of view of the physical meaning of both the process under study and the factors that were obtained as a result of the application of factor analysis. Therefore, when identifying factors that will be used for further analysis, one should be guided not only by mathematical methods, but also by the physical meaning of identifying factors. Thus, the use of factor analysis in the study of material science problems (for example, the welding process) is reduced to the search and analysis of the most significant characteristics of the process (factors) among the data array that can be obtained during the process under study. Purpose. Investigation of the relationship between the structural state in the zones of the welded joint after laser welding of specimens from steel 10KhSND using the mathematical apparatus of factor analysis. Conclusion. In this work, the study of the relationship of the distribution of the structural state over the zones of the welded joint was carried out using the mathematical apparatus of factor analysis.

Reaction of Cylindrical 09G2S and 10KhSND Steel Shells with Longitudinal and Annular Welded Joints to Explosive Loading

Large explosion-proof chambers are manufactured using cylindrical shells made of sheet metal by rolling and welding with addition of longitudinal and circumferential seams. In this case, one should make a choice of steel with increased strength or ductility. In this regard, this work presents the results of a study of the reaction of such 09G2S and 10KhSND steel shells to dynamic loading.

On the disperse acicular ferrite formation in the structure of cold-resistant joints under temperatures up to –70°С in MMA welding of 10KhSND steel. Part 1

The article presents an analysis of the metallurgical techniques that provide high quality electrodes for manual arc welding of low-carbon low-alloyed cold-resistant steels. It is shown that it is possible to improve technological and operational properties of welded joints at very low climatic temperatures up to –70°C implementing micro-alloying of the weld metal with nitrogen, titanium, cerium oxide and diamond nanopowder produced by detonation synthesis. The composition introduced into the electrode coating modifier mixture is identified. The cumulative effect of its components on the weld impact strength under temperature testing within the range from –20 up to –70°C was established. The matrix of the weld metal is composed mainly of disperse acicular ferrite, hardened by nanoparticles allegedly nitrides and carbonitrides of titanium and aluminum. It is shown that the centers for the crystallization of acicular ferrite are micro-sized non-metallic inclusions formed on ultrafine titanium nitrides. It was revealed that the toughness of the weld metal at low climatic temperatures is higher than toughness of joints welded by massively imported Japanese KOBELCO electrodes LB-52U. The results of the study make it possible to increase the cold resistance of welded structures for petrochemical plants and other facilities located in the Extreme North of the Russian Federation.Part 2 of the article will be devoted to the study of the welding and technological properties of coated electrodes.

Reaction of Cylindrical Shells Made of 09G2S and 10KhSND Steel with Longitudinal and Annular Welded Joints to Explosive Loading

Reaction of Cylindrical Shells Made of 09G2S and 10KhSND Steel with Longitudinal and Annular Welded Joints to Explosive Loading

Increasing the Corrosion Fatigue Resistance of Welded Joints by High-Frequency Mechanical Peening

The cyclic life of butt- and T-welded joints in as-welded condition and after strengthening by high-frequency mechanical peening has been studied. The welded joint specimens were made from a 12 mm thick rolled sheet of commonly used weathering steels 10KhSND and 15KhSND. The fatigue tests were carried out in air and in a corrosive medium (in a 3% NaCl solution) under pulsating tension with a frequency of 5 Hz. It has been found that high-frequency mechanical peening as a method for the plastic surface deformation of the joint metal near the fatigue damage localization sites increases the cyclic life of welded joints in air by a factor of over 10. It has been confirmed that in tests in a corrosive medium, the short-time fatigue strength of welded joints both in initial and in strengthened condition decreases. It has been shown that as a result of strengthening by high-frequency peening, the corrosion fatigue resistance characteristics of butt-welded joints of 15KhSND steel are significantly improved: the cyclic life increases by a factor of 4–10 depending on the level of applied stresses, the short-time fatigue strength, based on 2 · 106 cycles, increases by 85%. It has been found experimentally that in a 3% NaCl solution, strengthening increases the cyclic life of T-welded joints of 15KhSND and 10KhSND steels by a factor of 4–10 and 3.5–4, respectively, and that the short-time fatigue strength, based on 2 · 106 cycles, increases by 114 and 80%, respectively. Most strengthened specimens failed in the base metal, far from the fusion line; the unstrengthened specimens failed only in the transition area between the weld metal and base metal.

Special features of welding 10KhSND low-alloy structural steel with an oscillating laser beam

Experimental results confirm that deep penetration welding with oscillations of the laser beam influences formation of the structure, shape and quality of a welded joint. The results of metallographic studies are used to determine the values of the oscillation parameters of the laser beam at which the risk of formation of defects in the welded joint is reduced. The results of mechanical tests and microhardness measurements of the welded joints produced by laser welding with an oscillating beam in 10KhSND steel are presented.

Магнитный контроль сопротивления усталости сварных соединений

Introduction. Complexity of welded joints nondestructive testing under operation conditions is associated with the heterogeneity of the metal structure within the heat-affected zone, which is a stress concentrator; the metal structure in this zone is being changed under cyclic loads. The work aim was to investigate the possibility of applying a coercimetry method to diagnostics of welds working under cyclic loads.
 Method. At low-cycle fatigue irreversible damage accumulation takes place even in a defect-free weld. The magnetic structurescope KRM-Ts-K2M was used for detection of this damage by the value of the coercive force increase. The impact of load parameters on a coercive force was studied on the basis of static and cyclic testing of samples with butt and fillet (T-shaped) welds.
 Results. Numerous static and cyclic testing of welds and base metal have enabled the author to determine correlation between a coercive force value and weld resource parameters for the conventional steel grades St3sp, 09G2S and 10KhSND. Prospects of small (with the base ≤ 20 mm) sensors application for weld local diagnostics has also been shown in the work.
 Conclusion. Combination of magnetic structural testing by a coercive force method with an ultrasonic inspection makes it possible to predict a physical resource of metal work at the examination of hazardous production facilities.

Interaction of titanium dioxide with the weld pool in automatic submerged-arc welding of 10KhSND steel with a metallochemical addition

The theory of thermodynamics of heterophase reactions is used for examining the interaction of the metallochemical addition with the weld pool in automatic welding of 10KhSND steel under a layer of AN-47 flux. It is shown that the addition of titanium dioxide to the weld pool using a granulated filler results in the reliable supply of the addition to the reaction zone with uniform distribution in the entire volume of the pool. The total area of the ‘granulate–melt’-specific interfacial surface is 15 times greater than the specific area of the ‘liquid slag–weld pool’ interfacial surface. The structure of the weld metal combines the high parameters of strength, ductility and toughness.

Structure and phase composition of the surface layer on steel after alitization

Studies have been made on the structure and on the phase and elemental compositions of the diffusion layer obtained by depositing an aluminum gas-thermal coating on steels St3sp, 10KhSND, and 09KhN2MD with subsequent heat treatment.

Studying and Mastering the Controlled Rolling of Sheet for Side Members

The production of sheet for side members ‐ a product delivered to automobile factories in Russia and Belarus ‐ has been successfully introduced on the 800 mill at the Orsk-Khalilovo Metallurgical Combine (Nosta company). In accordance with the orders the combine has received, the sheet is made in widths of 310‐430 mm from steels 15GYuT, 20GYuT, 17G2(17G1), 13G2AF, 10KhSND, and 10KhSNDA. As is known, sheet produced for the side members of automobiles must have high indices for strength, ductility, cold resistance, and weldability, since the members are subjected to dynamic loads (mainly alternating bending loads) while in service, and needs to meet the requirements of TU 14-1-4632‐93. The technology used to make the sheet involves producing the steel in electric-arc furnaces, rolling ingots on a 1250 blooming mill, heating the blooms in the heating furnaces of an 800 mill, and rolling them on that mill with a force of 8.4 MN. The 800 mill consists of a reversing two-high universal roughing stand, a continuous finishing train of four-high stands, and a water-air cooling unit for accelerated cooling of the sheet. The sheet is heat-treated (normalized) after rolling. The goal of the project we undertook was to develop and successfully introduce a technology for the production of universal sheet that can be used to make automobile side members. We wanted the heat treatment of the sheet to take place during the final stage of the rolling operation in the normalization temperature range ‐ a range of temperatures somewhat higher than the critical temperature (Ac 3  820‐870°C for most low-alloy steels). This would make it possible to obtain a set of properties similar to those of normalized metal [F. Khaisterkamp, K. Khulka, Yu. I. Matrosov, et al., Niobium-Bearing Low-Alloy Steels. “Intermet Engineering,” St. Petersburg, Moscow (1999)]. Studies were performed on steel 20GYuT, which was designed for the fabrication of side members at the Kama River Truck Plant. To obtain rolled products of the desired types, we make steel 20GYuT with a carbon equivalent C e = 0.37‐0.47% (C e = C + Mn/6 + Si/24, where C, Mn, and Si are the mass contents of carbon, manganese, and silicon in the steel, %). The semifinished products are heated in the walking-beam furnaces of the 800 mill to temperatures of 1240‐1260°C and then rolled on the mill (the finishing temperature in the continuous finishing train is no higher than 850°C). The rolled products then undergo forced cooling in a water-air cooling system to a temperature no higher than 760°C. This is done to alleviate striation in the structure of the sheet metal. The rolled products are normalized at 940‐970°C and pickled in the hot-pickling section of the 800 mill. It was found that when the existing regime is used on the 800 mill to roll sheet of steel 20GYuT with a carbon equivalent greater than 0.39%, the strength and hardness properties of the sheet are good but its ductility and toughness characteristics do no satisfy the requirements of TU 14-1-4632‐93. Taking this into account, we used blooms from regular production heats with C e < 0.39% when we devised new regimes for normalization rolling. The blooms were rolled in the continuous finishing train of the 800 mill while varying the finishing temperature within the range from 850 to 950°C and avoiding use of the water-air cooling unit. The results of chemical analyses of the experimental heats are shown in Table 1 in comparison to the requirements of TU 14-1-4632‐93. Figures 1 and 2 show the dependence of the strength, ductility, and toughness properties of steel

Tendency of steels 10KhSND and 09G2S towards brittle failure

The tendency towards brittle failure of low-alloy steels type 10KhSND and 09G2S at low temperatures depends on the supply condition. The highest resistance to brittle failure occurs for steel after temper hardening, i.e., quenching and high-temperature tempering. A changeover into a brittle condition for temper hardened steels of the test melts commences at −60°C, and for hot-rolled steels it commences at −40°C.

Characteristics of static and fatigue strength and of crack resistance of welded joints in structural steels at low temperatures. Communication 1

The article presents the results of experimental investigations of the effect of low temperatures (down to 77°K) on the resistance to static and low cycle deformation and rupture of steels 09G2S, 10KhSND, 06G2AF, 20KhGSA, 07Kh3GNMYuA, and ON6. It also presents the dependences of the theoretical characteristic of low cycle fatigue mTe of steels at low temperature under rigid loading on the index of ductility {ie022-01} under static loading and test temperatures down to 77°K.

Improving the strength characteristics of hot-rolled steel 10KhSND

Improving the strength characteristics of hot-rolled steel 10KhSND

Increasing the strength of hot-rolled steel 10KhSND

1. Increasing the concentration of manganese to 1.0% in steel 10KhSND increases the ultimate strength without changing the yield point. 2. An increase in the ultimate strength and the yield point while maintaining the same levels of ductility can be achieved by adding 0.03–0.07% Ti to steel 10KhSND. In order to increase the strength of steel 10KhSND in the hot-rolled condition, we recommend the addition of Ti in amounts close to the maximum allowable according to State Standard 19282-73 (0.03%). 3. The increased strength of steel 10KhSND containing increased amounts of Ti of 0.025–0.030% occurs as a result of decreased grain boundary elongation and a decreased tendency toward grain growth.