Carbon Steel Grades Research Articles

STUDY OF THE INFLUENCE OF THE CHEMICAL COMPOSITION OF RAILWAY AXLE STEEL ON THE UNIFORMITY OF THE FINAL MICROSTRUCTURE

The relevance of the work. For modern railway transport, increasing the strength and operational reliability of rolling stock parts, in particular railway axles, is an urgent task. It is known that the inhomogeneity of the distribution of chemical elements in the structure of structural grade carbon steels is formed mainly during their crystallization and may subsequently affect the final structural state and set of properties. Purpose. Study of the influence of the chemical composition of steels for railway axles on the uniformity of the structure. Methodology. Experimental ingots of different chemical compositions with different amounts and ratios of the main chemical elements within the range of OS and EA1N were produced in laboratory conditions. The grain structure was studied on microsections after etching with nital. Chemical inhomogeneity (“traces” of the dendritic structure) − the distribution of chemical elements in the microstructure of cast samples was detected by etching in a hot solution of sodium picrate. Metallographic analysis was performed on a light (optical) microscope “Axiovert 200 M MAT” manufactured by “Carl Zeiss”. The results. The effect of changing the chemical composition of carbon steel, which is intended for the manufacture of railway axles, on the peculiarities of the formation of ferrite-pearlite heterogeneity and grain size is determined. It is shown that in samples of steels corresponding to the EA1N brand with a lower carbon content, the distribution of phases is uneven. The mechanism of formation of such a structure is explained from the point of view of two theories. In samples of steels with an average carbon content, which correspond to steel of the OS grade, the distribution of the pearlite and ferrite phases is more uniform, the relationship between the size and the degree of darkening of the pearlite areas with the order of the former dendritic branches has been established. Based on the results of the quantitative analysis of the final grain structure, it was established that OS steel with an average carbon content at different Mn/Si ratios has a more uniform grain structure. EA1N steel with a lower carbon content has a pronounced grain size, with an increase in the Mn/Si ratio, the largest maximum of the dependence of the distribution shifts to a larger grain size (smaller number). Practical results. Increasing the homogeneity of the final microstructure contributes to increasing the plasticity and viscosity of steel, which directly affects the reliability and durability of railway axles.

The upper bound of the buckling stress of axially compressed carbon steel circular cylindrical shells

Abstract The buckling stress of axially compressed circular cylindrical shells (CCSs) is highly sensitive to imperfections. The literature proved that it is hard to generalize the imperfections and the designers are encouraged by the Eurocode EN 1993:1-6 (2007) to conduct geometric and material nonlinear with imperfections analysis (GMNIA) considering different possible forms of imperfections for the shell under design. As GMNIA type of analysis is difficult and requires highly skilled engineers, knowledge of the upper limit of the buckling stress serves as a guide and prevents the overestimation of the shell buckling resistance. It also encourages average skill designers to attempt GMNIA as far as the maximum possible limit is known. Thus, the objective of this study is to provide the upper bound of the buckling stress of carbon steel CCSs. Geometric and material nonlinear analysis (GMNA) of perfect circular cylindrical shells for a wide range of R/t ratio is conducted. It has been found that for cases of small and intermediate R/t values the buckling stress can be predicted by GMNA while the elastic buckling controls those of larger R/t values. The limiting R/t values depend on the steel grade and have been derived for the available standard grades of carbon steel. The obtained results are presented in terms of simplified formulas and a design chart to be used by engineers. Application of the proposed upper bound in simplified design approaches using knock down factor (KDFs) has also been discussed.

THE EFFECT OF ARC STUD WELDING PARAMETERS ON MECHANICAL PROPERTIES OF DOCOL 1500M ADVANCED HIGH STRENGTH STEEL WELDING JOINTS

Arc stud welding method is a welding method that takes advantage of the arc's ability to melt metals. Stud welding is an easy and fast welding method that is generally applied to surfaces where threading is problematic and welding is difficult. Docol 1500 martensite materials are high-strength steels with high tensile strength up to 1700 MPa and good ductility. These type of materials provide high efficiency, especially in the automotive industry, in terms of both vehicle lightness and advanced crash protection. In this study, the weldability of threaded studs made of 20MnB4 grade carbon steel was investigated using the arc stud welding process on Docol 1500M plate. The arc stud welding process was carried out using a ceramic ferrule at different combination values with electric current values ranging between 300A and 500A and different welding times ranging from 0.125 seconds to 0.300 seconds, as well as variable welding parameters such as 3mm plunge value and 5.9mm lift distance. With the experimental study, the most suitable welding parameters were try to determined according to the size and properties of the materials to obtain a quality welded. At the end of welding process, the effects of arc stud welding parameters such as welding current, welding time, plunge and lifting distance on mechanical and microstructural properties were experimentally investigated.

Comparison of contamination by non-metallic inclusions in continuous cast slabs of special low carbon steel

The paper studies and compares the macrostructure quality of continuously cast slabs of extra low carbon steel grades DX54D, DX56D, DX57D and 006/IF during casting on a curved-type CCM with and without a vertical section. For this purpose the array of production data of casting of steel of the above mentioned grades, totaling 383 melts, was studied. At the same time, 149 melts were cast on four CCMs (conventionally named A, B, C, D) of curvilinear type with a base radius of 8 m, and 234 melts – on a machine of curvilinear type (E) with a base radius of 11 m and a vertical section of 2.7 m length. Contamination of the cast metal with non-metallic inclusions was assessed metallographically by the degree of development of the defect “point heterogeneity”. The presence of a vertical section allows to reduce the degree of development of point heterogeneity from 1.29 to 0.75 points – by 0.54 points or by 41.9% (relative). With a probability of 99.9% we can assert that the difference between the average values of point heterogeneity is not random and is limited by the presence of the vertical section of the CCM

Development of TRIP phenomenon using power refining of retained austenite by niobium

AbstractThe illustrations above demonstrate that as the percentage of niobium increases, the grain size decreases, leading to an increase in the stability of transformation induced plasticity steel. This, in turn, results in improved mechanical strength. The optimal volume fraction of retained austenite for a significant transformation induced plasticity effect to occur is reported to be in the range of 10 vol. %–20 vol. %. The volume fraction of retained austenite directly determines the carbon content and grain size of the retained austenite, its two main stabilization factors. The stability of the retained austenite dictates when the strain‐induced martensite transformation (SIMT) occurs during straining of transformation induced plasticity high strength steel. Unstable retained austenite transforms almost immediately upon deformation, increasing work hardening rate and formability during the stamping process. At the appropriate stability of the retained austenite, the Strain‐Induced Martensite Transformation begins only at strain levels beyond those produced during stamping and forming, and the retained austenite is still present in the final part; it can transform into martensite in the event of a crash, providing greater crash energy absorption. The tensile strength level of micro‐alloyed transformation induced plasticity steels may exceed 1 GPa. Grain refinement mechanism is considered as the most applied mechanism used in increasing of steel strength without deterioration of ductility and toughness. Recently, it was proposed that the grain refinement could act positively on promoting the transformation induced plasticity effect of advanced high strength steel through improving the stability of retained austenite. In this research, quenching and partitioning heat treatment technique was applied to four grades of low carbon steel with different percentage of niobium. Then, the effect of niobium on grain refinement has been detected by microstructure observations. Mechanical properties and strain hardening properties of investigated steel have been determined. In addition, by using x‐ray diffraction, as well as a new electric resistance‐based sensor, it was possible to characterize the stability of the retained austenite through the plastic deformation of steel. Grain refinement by using of niobium has a great impact on promoting the stability of retained austenite against the plastic stress at the plastic deformation zone.

Mechanical Properties and Microscopic Evaluation of Heat Treated D6A Ultra High-Strength Steel

This investigation aims to evaluate the influence of heat treatment on the hardness and microscopic characteristics of a specific grade of medium carbon steel, namely, the American standard D6A Ultra High-Strength Steel, which contains 0.47% carbon in its composition. After preparation, specimens were heated in a muffle furnace at a temperature of 830°C and held for 90 minutes, followed by quenching. Subsequently, the specimens underwent tempering at a temperature of 600°C for 60 minutes. The hardness and microscopic evaluation of the heat-treated steel were determined. The results also indicate a rapid increase in hardness with a decrease in thickness for the heat-treated material. For HRA (Rockwell Hardness A Scale) times of 5s and 10s, the hardness enhancement percentages were 29% and 103%, respectively, compared to specimens without heat treatment. Furthermore, a chamber pressure test assessed the suitability and optimal design of Ultra High-Strength Steel for a pressure vessel in a mortar gun. As the outer radius increases, there is a corresponding decrease in axial stress, hoop stress, and the maximum limit of ultimate stress for both internal pressures within the pressure vessel. For internal pressures of 100 MPa and 85 MPa, the optimal inner radius for the pressure vessel is determined to be 0.053m and 0.051m, respectively.

Analysis and Experiment of Blank Holder Gap in the Cylindrical Cup Deep Drawing of Low Carbon Steel to Prevent Cracking-Wrinkling

This paper aims to investigate Blank Holder Gap (BHG) in order to prevent wrinkles and crack defects in the deep drawing process of cylindrical cups with a diameter of 30 mm, using low carbon steel grade SPCC that is 0.7 mm thick. Mathematical and experimental approaches were applied to study the effect of BHG on wrinkle wave height and product quality. The analytical approaches used were the slab method and the Forming Limit Diagram (FLD) to determine the final thickness of the product specimen and the height of the wrinkling wave, respectively. Each method in this study had been compared to each other. Punch-die dimensions were determined based on the standard tool designed. According to the research, BHG is set 100% to 114% of the thickness of the initial material or equivalent about 0.70 to 0.80 mm. By using the value of this gap, the height of wrinkles can be avoided, the magnitude of the drawing force is still below the critical limit, and the product specimen does not experience wrinkles and cracks. The results of this study are applicable to the deep drawing of cup products on SPCC material with a thickness of no more than 1 mm.

Investigation on the effect of reduction process on internal quality of high carbon steel billet and its evolution in as-rolled wire rod

The effect of reduction process, especially the reduction zone on the internal quality of continuous casting high carbon steel billets was studied by shifting active reduction rolls while at same casting condition, as well as identical reduction amount and gradient. In the present study, the heredity of the main internal defects emerged in billets with different reduction zones was also investigated after subsequent rolling process in terms of severity, regional distribution, and microstructure formation as well. For the investigated high carbon steel grade, the evolution of the internal quality in relation to the macrosegregation, internal crack and porosity illustrates the effectiveness and importance of applying mechanical reduction for the homogeneity improvement from the cast billet to the as-rolled wire rod product. Meanwhile, it is also suggested by the investigation the necessity of fine control for the implement of mechanical reduction process, or it may not have sufficient positive impact on homogeneity and compactness of billet and as-rolled product, but some other undesirable defects may even be induced by mechanical reduction.

Laser beam oscillation welding for fatigue properties enhancement of tailor-welded blanks

Dissimilar thickness laser welded tailored blanks of two low-alloyed carbon steel grades were fabricated. Laser welds made without beam oscillation exhibited serious root undercuts. Although these notches did not degrade the tensile strength, they were detrimental to the fatigue lifetime of a weld joint. Therefore, laser welds with three different beam oscillation modes to modify the root were examined. Application of beam oscillation improved fatigue properties in all tested cases. The best results were achieved with line oscillation, even though this mode did not suppress weld root notches, suggesting other factors, besides joint geometry, contributing to the resulting fatigue properties.

Numerical and experimental failure analysis of wind turbine blade fastener

The objective of this study is to conduct a root cause failure analysis on wind turbine fasteners constructed from carbon steel Grade 10.9. The presence of corrosion pits at the thread root, as well as beach and ratchet marks on the fracture surface, suggests that the fastener failed due to a corrosion-fatigue mechanism. The microstructure of the failed fastener predominantly consisted of 98 % tempered martensite, with some bainite and a small amount of chromium carbides, which is characteristic of quenched and tempered low alloy steel. Magnetic particle testing revealed similar crack marks on other fasteners in similar locations, indicating the points of maximum stress in these fasteners. Furthermore, finite element analysis using Abaqus software demonstrated that for a corrosion pit to grow, it required a minimum pit length and depth of 0.5 mm and 0.6 mm, respectively.

Correlating dry wear turning and pin-on-disc tests: a cost-effective approach to machinability evaluation for low carbon steel grades

Machinability tests play a crucial role in the metalworking industry despite their inherent cost and time requirements. This study aims to introduce a novel approach by establishing a correlation between the dry wear turning and pin-on-disc tests, potentially enabling their interchangeability. The industry is particularly interested in this challenge due to the simplified implementation and reduced costs and time compared to the conventional turning test. The correlation between the dry wear turning and pin-on-disc tests was investigated using three low carbon steel grades (12L14, 1212, and 1018) and three medium cutting speeds (150, 180, and 240 m/min). Additionally, a comprehensive cost-energy comparison is conducted to underscore the significance of identifying a laboratory test equivalent to the traditional machinability test. The obtained results reveal a strong correlation between both wear tests. Furthermore, the relative cost analysis demonstrates that the pin-on-disc test costs only 14% of the long-duration turning test, emphasizing its cost-effectiveness.

Unravelling the corrosion processes at steel/bentonite interfaces in in situ tests

AbstractMicroscopic and spectroscopic analyses were conducted on steel/bentonite interface samples removed from four in situ experiments that were carried out in three underground research laboratories at different temperatures and under different hydraulic and geochemical conditions. The results provide valuable information about the corrosion processes occurring in high‐level radioactive waste repositories. Systematic patterns can be deduced from the results, irrespective of carbon steel grade, type of bentonite and its degree of compaction, geochemical environment or experimental setup. Thus, a clear dependence of the corrosion rates on temperature and exposure period, as well as on the availability of H2O and O2 provided by the surrounding bentonite buffer, is observed. Furthermore, Fe(II) ions released by corrosion interact with the structural Fe in the clay. Recent developments highlight the usefulness of reactive transport modelling in understanding the coupled corrosion and Fe–clay interaction processes.

Characterization of asphaltene removal mechanisms from well columns using surface energy

The deposition of asphaltene in well columns would compromise flow assurance and possible occurrence of under deposit corrosion. The formed deposit is the net difference between deposition and removal of asphaltene fouling. While there has been a body of research on deposition, the subjects of removal and its dominant mechanisms have received less attention. The present study therefore examines the most important removal mechanisms of shear force, rolling, and rebound under field operating conditions. To achieve this, the removal critical velocity was examined as a function of oil properties of density (870–1000 kg/m3) and viscosity (1.5–3.0 cP), casing diameter (4.5–7 in), and casing substrate (two grades of carbon steel). Experiments were used to determine the preliminary surface energy/tension characteristics of the investigated casing surfaces, crude oil sample, and crude oil-extracted asphaltene particles. The findings revealed that the casing substrate would profoundly influence the removal of asphaltene from the surface whereas the impact of oil properties and casing diameter would be meagre. Furthermore, the larger the asphaltene particles, the greater the possibility for asphaltene removal. For similar thermodynamic, hydrodynamic, and geometrical conditions, the rebound is the major mechanism for removal of asphaltene deposits, according to the predicted critical removal velocities. Finally, to calculate the proportion of precipitated asphaltene particles that would ultimately attach to the surface of the casing, the sticking probability is examined.

Определение оптимальных технологических параметров процесса очистки деталей в погружных моечных машинах

Cleaning and washing contaminated surfaces of machine parts is relevant in the repair industry. Improving the efficiency of the process of cleaning metal parts is possible using a combination of submersible, jet and ultrasonic methods. The variety of designs of washing machines and installations using different cleaning methods requires the determination of optimal technological parameters and process modes, as well as the identification of an effective washing solution. For this purpose, an experiment was carried out on the process of cleaning metal parts from the remnants of cutting fluids (coolants) in submersible washing machines using ultrasonic vibrations. Solutions of dimer, labomid, and soda ash were studied to clean metal parts from coolant residues. To intensify the process of washing metal parts, an ultrasonic unit UZDN-A with a constant oscillation frequency was used. The degree of purification of metal parts was estimated by the ratio of the mass of the pollutant removed from its surface to its initial mass, in percent. The obtained mathematical models of the degree of cleaning of metal parts (for grades of structural carbon steels and non-ferrous metals) from coolant made it possible to determine the optimal technological parameters: concentration of cleaning solutions 15 to 20%; working temperature for dimer - 20 to 30°C, for labomid - 70 to 80°C, for soda ash - 80 to 90°C. It has been established that the most energy-efficient and safe cleaning solution is a dimer, and the use of labomid for ultrasonic cleaning is not advisable due to its increased foaming. It was also found that the time of washing (the presence of metal parts in the machine) and the amount of oil on the surface of metal parts do not significantly affect the degree of cleaning.

How nitrogen alloying affects the structure of multilayer metal materials

This article deals with the way nitriding affects the structure of multilayer metal materials. The subject of research was a composition of alternating layers of the U8 carbon steel and austenitic 08H18n10 grade steel with various structuring degrees.

Development and Calibration of Thermoelectric-Power-Based Non Destructive Evaluation (TNED) Device for Aging Analysis of Carbon Steel SA 106B

The aging analysis of nuclear power plant components and materials is crucial for the power plant’s safety, and for its upgradation and life extension. The health monitoring of power plant materials, such as steel, is mostly done by employing conventional non-destructive evaluation (NDE) techniques. Considering the limitations associated with conventional NDE techniques, thermoelectric power based NDE (TNDE) is being explored. This paper presents the first ever development and successful demonstration of TNDE in Pakistan. Moreover, the aging analysis of carbon steel grade SA 106B is also being presented for the first time. The extraction-steam pipe samples (new and aged) of SA 106B, from a 46-years-old operating nuclear power plant, are being analyzed and the sensitivity of TNDE to aging induced changes in microstructure is demonstrated. Further, the aged SA 106B is simulated via heat treatment and the equipment is calibrated for its utilization in the nuclear power plant. The correlation between thermoelectric power (TEP) and Vicker hardness (HV) [TEP (µV/oC) = ~2x10-5 Hardness (HV) + 0.008] has been analyzed. It is revealed that the technique has the potential to analyze mechanical properties of aged extraction steam piping without cutting and taking the samples to the laboratory.

Побочные продукты окислительной десульфиризации судового маловязкого топлива — перспективные ингибиторы коррозии

The studies described in the article show that the by-product of oxidative desulfurization of low-viscosity marine fuel is a promising inhibitor of acid corrosion, showing anticorrosive activity in dimethylformamide medium with respectto carbon steel grade St3sp with a degree of protection of 75.5%. This will not only simplify the material support of the proposed alternative technological process of desulfurization of fuel and solve environmental problems, but also reduce the need of the domestic industry for expensive imported reagents.

CORROSION OF CARBON STEEL IN THE WATER BASINS OF SHEMKIR AND YENIKEND HYDROELECTRIC POWER PLANTS

Using gravimetric and electrochemical research methods, the corrosion-electrochemical behavior of carbon steel grade St3 in Kura river water has been. Gravimetric measurements were carried out under operating conditions of the Shemkir and Yenikend hydroelectric power stations for one year. Along with this, the ionic and bacteriological composition, as well as some physicochemical parameters of these waters were established. It revealed that St3 in the Kura water corrodes at a rate of (0.04÷0.05) g/m2•hour, which is characteristic of steel corrosion in fresh waters. In the atmosphere of hydraulic structures, steel corrodes at rather a low rate, i.e. (5÷6)10-3 g/m2 hour. As a result of biochemical analysis, sulfate-reducing bacteria (SRB) were discovered in these waters, which are a dangerous organism that releases the corrosive substance of H2S. By taking the anodic and cathodic polarization curves, a quasi-stationary steel corrosion rate was established to be 0.06g/m2 h.

Steam Boiler Design Using Diesel Motor Exhaust Gas

As it is known that the boiler is a device used to heat water. This research is conducted to propose another alternative in energy saving efforts by utilizing exhaust gas energy from Diesel motors which so far have not received much attention. The exhaust gases is reused to react the boiler. The method used in design this tool uses the literature study method. The data is taken from the exhaust gas of a 9 x 12 x 4 cylinders Diesel engine with a speed of 300 rpm and Mep 80 Psi, engine power (N) 92.4 Hp. From the results of this study, the results show that the size of the steam pipe with pipe outer diameter (OD) is 1 in, spaced 1 in, the number of rows is 2 rows, the number of pipes in one row Z = 12 rows, with carbon steel pipe material SA 106 Grade. Meanwhile, the size and arrangement of the economizer pipes are the outer diameter of the pipe (OD) 1 in, the spacing = 2 in, the number of rows = 6 rows, the total number of pipes Z = 2 x 6 = 12 pieces, the overall length of the pipe is L x 12, the economizer pipe = 644 in, and SA 106 Grade carbon steel pipe material. The thickness of the boiler drum t = 0.245 cm, capacity Q = 536.75 lb/hour, and the boiler drum material is SA 302 Grade B carbon steel.

Joining different grades of low carbon steel to develop unsymmetrical rod to plate joints using rotary friction welding for automotive applications

The main objective of this investigation is to optimize the rotary friction welding (RFW) parameters for maximizing the tensile strength (TS) and weld interface hardness (WIH) of rod to plate joints of different grades of low carbon steel and analyze the effect of RFW parameters on TS and WIH of joints. AISI 1018 and AISI 1020 grades of low carbon steel are joined to develop unsymmetrical rod to plate joint using RFW for automotive applications. RFW being a solid-state welding (SSW) was employed to avoid the problems in fusion welding and development of unsymmetrical joints such as solidification cracking, wider heat affected zone (HAZ) and distortion. The RFW parameters specifically friction pressure/friction time (FRNP/FNRT), forging pressure/forging time (FRGP/FRGT) and rotational speed (rps) were optimized using response surface methodology (RSM) to maximize the strength and hardness of rod to plate joints. The three factor – five level central composite design (3 × 5 - CCD) consisting of less experiments was employed for designing experimental matrix. The tensile strength and microhardness tests were performed to evaluate mechanical performance of rod to plate joints. The numerical and graphical optimization techniques of RSM were employed to optimize the RFW parameters. The 3D response surfaces were developed which show the optimum conditions of RFW parameters. The effect of RFW parameters on TS and WIH of rod to plate joints was analyzed from 3D response surfaces. The microstructural features of optimized rod to plate joint were analyzed using optical microscopy. The fractured surfaces of rod to plate joints were analyzed using scanning electron microscopy. Results showed that rod to plate joints developed using FRNP/FRNT of 3.71 MPa/s, FRGP/FRGT of 3.71 MPa/s and RTSP of 19.99 rps exhibited higher TS and WIH of 452 MPa and 252 HV0.5 respectively. The higher TS and WIH of rod to plate joints is attributed to the evolution of finer grain structure in weld zone and narrower HAZ. The RTSP revealed greater effect on TS and WIH of rod to plate joints followed by FRGP/FRGT and FRNP/FRNT.