Medium Carbon Steel Research Articles

Experimental Analysis of Heat Transfer Post Quenching of Medium Carbon Steel

<div>Transient temperature analysis is involved in the thermal simulation of the heat treatment process, in which the hot metal temperature changes with respect to time from an initial state to the final state. The critical part of the simulation is to determine the heat transfer coefficient (HTC) between the hot part and the quenching medium or quenchant. In liquid quenching, the heat transfer between the hot metal part and water becomes complicated and it is difficult to determine HTC. In the current experimentation a medium carbon steel EN 9 rod with a diameter of 50 mm and length 100 mm was quenched in water and ethylene glycol mixture with different concentrations. A part model was created; meshed and actual boundary conditions were applied to conduct computational fluid dynamics (CFD) analysis. In order to validate CFD analysis the experimental trials were conducted. Experimental results showed a reduced cooling rate for the specimen, and also a reduction in heat-carrying capacity of the mixture, which is attributed to the addition of ethylene glycol.</div>

Quasi-Static and Dynamic Crack Propagation by Phase Field Modeling: Comparison with Previous Results and Experimental Validation

In this paper, experimental tensile tests for pre-cracked high Carbon steel ‘C90’ specimens were performed for quasi-static and dynamic loading. High loading velocity affects the crack patterns by preventing deflection. On the other hand, an efficient numerical tool based on the phase field model was developed and validated to predict brittle fracture trajectories. A staggered numerical scheme was adopted to solve the displacement and damage fields separately. Implementation efficiency in initiating and propagating cracks, even from an undamaged microstructure, was proved. The effect of the critical fracture energy density Gc on the crack path was tested; with smaller Gc, the crack patterns become more complex. In addition, the impact of loading velocities was examined, and earlier and faster crack formation and greater crack branching is observed with higher impact velocity. In this study, bidimensional plane stress cases were treated. The phase field model with hybrid formulation was able to predict crack pattern and especially crack arrest and branching found in the literature. The developed model accurately determined the transition zone of the crack path topology that has been observed experimentally.

Effect of Carbon Content and Hard Phase Volume Fraction on Yield Strength in Friction Stir Processing of Low and Medium Carbon Steels

Effect of Carbon Content and Hard Phase Volume Fraction on Yield Strength in Friction Stir Processing of Low and Medium Carbon Steels

Studies on selective laser quenching by high repetition frequency lasers with scanning galvanometer

This study introduces a novel material processing methodology termed High Repetition Frequency Selective Laser Quenching (HRF-SLQ). This technique utilizes high-power lasers with a maximum power of 5 kW in conjunction with a scanning galvanometer, operating at elevated repetition rates up to 200 Hz, to specifically treat surfaces of high and medium carbon steels. The application of this method leads to the creation of allotropic metal matrix composite materials (A-MMCs). In general, the scanning speed of a galvanometer can range from hundreds to thousands of times per second. Based on the high acceleration and rapid jumping characteristics of the scanning galvanometer, this technology transforms the high-power laser heating of metal plates from continuous heating mode to parallel pulse heating mode, which repeats heating 30 to 200 times per second. This transformation ensures the quenched layer avoids melting even under prolonged irradiation times by high-power lasers. Consequently, it can significantly enhance processing efficiency by selective laser quenching (SLQ), ensuring that the depth of the hardened layer reaches 0.88–0.94 mm and keeping the surface smooth without melting. This paper systematically investigates the influence of various processing parameters, such as laser power (P), single heating time (t1), and the number of processing units (N), on the depth of the SLQ and the quenching efficiency. It also examines the impact of HRF-SLQ technology on the properties of A-MMCs and analyzes temperature field variations from room temperature to melting point through simulation methods combined with laser quenching experiments.

Composition and treatment of wear resistant steel for application in mining industry

The service life of machines in the mining industry is in the most cases determined by wear rate of parts in contact with the rock and soil. This work demonstrates the results of investigation on wear resistance of high-carbon low-alloy steel under abrasive wear. Steel samples containing 1.2 wt.% of carbon, 3 wt.% of manganese and 2 wt.% of silicon were hardened from 900 °C and 1000 °C and subjected to two-body and three-body abrasion tests. It has been established that after heat treatment this steel has increased abrasive wear resistance due to the phase transformation of unstable austenite into deformation-induced martensite. The results of study of near-surface region microstructure of samples after wear are presented. X-ray diffraction analysis and measurement of the microhardness of the worn surface were also carried out. It has been established that during abrasive wear a continuous layer of deformation martensite with a microhardness of 1300-1400 HV 0.05 is formed at a depth of up to 10 μm. Such a microhardness significantly exceeds the microhardness of quenching martensite. The results of the work can be used to increase the service life of wear parts of mining equipment.

Improved uniform ductility in a high-carbon pearlitic steel via microstructural homogeneity architecture

In this work, the nucleation and growth kinetics of pearlitic transformation are quantitatively investigated to unveil the distinctive microstructural evolution behavior under a high undercooling degree. Both intra-granular and inter-granular nucleation increasingly occur with 1-2 orders of magnitude increase in nucleation rate N˙. However, a moderate increase in the growth rate GV, namely a larger N˙/GV ratio, leads to a 30%–40% size reduction in pearlitic colonies. The avalanche-type increase in nucleation events induces a more random distribution of ferrite orientation among colonies that possess a slight increase in relative misorientation but a pronounced increase in accumulative misorientation, and an arbitrary alignment of Fe3C lamellas in colony interior. Such improved microstructural homogeneity ensures more uniform and localized deformability, which allows compatible deformation between colonies or within colonies and prevents the expansion of newly-formed cracks. These results provide guidance for industrial manufacture of high-carbon pearlitic products with high safety and reliability, resulting from the improvement in localized deformability, and for low-cost wires via reducing the drawing passes, stemming from the significant increase in uniform deformability.

Production of complex Fe-Si-Mn-Cr ferroalloy using high-ash coal: a sustainable metallurgical approach

The article presents the results of comprehensive thermodynamic modeling and laboratory tests conducted for smelting a complex ferroalloy of silicon, manganese, and chromium (Fe-Si-Mn-Cr) from chromium, medium-grade manganese ores, and high-ash coals from Kazakhstan. Thermodynamic analysis was performed using HSC Chemistry software to model the Fe-Si-Mn-Cr smelting process over a temperature range of 900 °C–1800 °C. This analysis involved six actual charge compositions with solid reductant (Csolid) consumption ranging from 5 to 20 kg per 100 kg of Cr and Mn ore mixture. The mechanism of the combined carbothermic reduction of Cr, Mn, Si, and Fe was investigated using the Cr-Si-Al-Ca-Mn-Mg-O-C system. According to thermodynamic data, the optimal consumption of Csolid per 100 kg of ore mixture is 17 kg, and the optimal temperature range for smelting ferroalloys is between 1600 and 1700 °C. Laboratory tests were conducted in a high-temperature Tamman furnace at 1700 °C, resulting in experimental samples of the new complex ferroalloy with an average composition of 14.85% Fe, 14.05% Si, 7.55% Mn, 57.54% Cr, and 6.01% C, with P < 0.03% and S < 0.02%. The phase composition included (Cr, Fe, Mn)3Si and carbides Cr23C6 and (Fe, Mn)3C. The resulting alloy is suitable for alloying high-carbon and tool steels.

Effect of welding speed variation on bead geometry of IN-625 weld bead on a medium carbon steel plate using synergic GMAW process

Gas Metal Arc Welding (GMAW) is widely applicable across various sectors due to its ease of operation, higher welding speed and high production rate. The present work aims to determine the effect of welding speed in a synergic GMAW process with ER-NiCrMo-3 wire to produce a bead-on-plate on AISI 4140 base material. The results showed that the beads produced were free from defects like porosity and cracks. The increase in welding speed decreases heat input (HI), bead penetration and weld width. However, the effect of speed was found least in heat input and most in bead penetration. The variation in bead geometry hence, clearly suggests that welding speed plays a significant role in the selection of weld parameters during the fabrication of IN-625 joints.

A Turn-Off Fluorescent Sensor for Metal Ions Quantifies Corrosion in an Organic Solvent

We demonstrate that the corrosion of AISI 1045 medium carbon steel and pure aluminum can be quantified by the turn-off fluorescent sensor Phen Green-SK (PGSK) in ethanol-based solutions. We first evaluate the dependence of the chelation enhanced quenching of PGSK on iron and aluminum ion concentrations. Subsequently, we apply PGSK to examine the anodic dissolution of metal corrosion. The observed time-dependent PGSK-quenching quantifies the corrosion rates of two metals over 24 h of immersion in ethanol-based solutions. The PGSK-based quantification of corrosion is compared to scanning electron microscopy and electrochemical techniques, including open circuit potential and Tafel extrapolation. The corrosion rates calculated from PGSK-quenching and Tafel extrapolation are in agreement, and both indicate a decrease in corrosion rates over 24 h. Our work shows PGSK can efficiently sense and quantify anodic corrosion reactions at metal interfaces, especially in organic solvents or other non-aqueous environments where the application of electrochemical techniques can be limited by the poor conductivity of the surrounding medium.

Grain Boundary Segregation Behavior and Thermodynamic Analysis Based on CALPHAD Method for B Added High Carbon Steel

Grain Boundary Segregation Behavior and Thermodynamic Analysis Based on CALPHAD Method for B Added High Carbon Steel

The durability increasing of high-wear cast parts of mining and processing equipment

The analysis of the operation of rapidly wearing parts of the ore-grinding equipment was carried out. It has been established that unloading grates and ladles are fast-wearing parts of layered fracture mills and determine their downtime between repairs. The possibility of improving the mechanical properties of medium-carbon steel 40HL due to the reduction of harmful impurities is shown. The effects of modification with aluminum, vanadium, calcium, and rare earth metals on structural formation, mechanical, and operational properties of steel are investigated. It was established that the complex modification of cast steel 40HL (0.04…0.1% vanadium, 0.15% silicon calcium and 0.15% rare earth metals) allows to significantly increase its mechanical properties and wear resistance. The separate and joint influence of aluminum, vanadium, calcium and rare metals on the austenite grain size and hardening of steel was studied. The proposed modification technology makes it possible to obtain a fine grain, through-hardening of castings and ensure reliable and long-lasting operation of ball mills.

Medium-carbon dual-phase steels with spheroidized ferrite matrix

This study presents processing and properties of dual-phase (DP) steels, which contain islands of martensite among ferrite grains effectively reinforced by abundant carbide particles. To this end, a medium-carbon, low-alloyed steel plate with an initial ferrite-pearlite microstructure underwent cold rolling for 80% thickness reduction. Specimens obtained from the cold rolled strip were then heated in a neutralized salt bath at various temperatures ranging from 600 to 730 °C for 10 ks, followed by water quenching. The resulting microstructures and mechanical properties were analyzed. Preceding the formation of austenite during intercritical annealing, recrystallization led to the formation of a spheroidized ferrite microstructure with a high number of carbide particles dispersed mainly within the recrystallized ferrite grains. Initially, austenite grains formed on the carbides located at the boundaries between ferrite grains, followed by the formation of austenite on the carbides still present within the ferrite grains. Quenching from 715 °C resulted in a DP microstructure with intergranular martensite while increasing the annealing temperature to 725 °C led to the creation of intragranular martensite additionally. The study also focused on the distribution of alloying elements in the DP microstructure, revealing an enrichment of carbides with Mn, Cr, and Mo. Furthermore, an enrichment of martensite islands with manganese atoms was identified, but no comparable enrichment with carbon atoms was observed. The specimens annealed at 715–725 °C, which consisted of a martensite volume fraction ranging from 0.15 to 0.45, exhibited a superior balance of strength and ductility, as well as an outstanding work hardening exponent.

Effects of two-step austempering processes on the wear resistance and fatigue lifetime of high-carbon nanostructured bainitic steel

The previous research on two-step austempering processes have been mainly focused on the bainitic transformation kinetics, with few details the relationships between the parameters of two-step austempering process and the wear properties and fatigue lifetime. In this paper, the effects of two-step austempering process on wear resistance and fatigue life of high carbon nano-bainite steel were investigated. The results show that the first-step bainite with high volume fraction prolongs the total bainite transformation time. The two-step austempering samples contain finer bainitic ferrite plate and higher volume fraction of retained austenite, as well as resent excellent hardnesses, tensile properties, wear resistance and fatigue lifetime. In particular, the wear resistance of the 50%-290 °C sample is better than that of the 210 °C sample, this is caused by the transformation of the high fraction of retained austenite in the two-step austempering samples into hard martensite and the microstructure refinement zone that forms on the surface of the sample during the wear process. The 50%-290 °C sample have better fatigue properties at low total strain amplitudes (0.7% and 0.8%). When the total strain amplitude is 0.7%, the fatigue life of the 50%-290 °C sample is 57.5% higher than that of the 210 °C sample, which is because of the higher yield strength and finer microstructure of the 50%-290 °C sample. These results support the later study of controlling two-step austempering process for high-carbon nanostructured steels.

Effect of Boron on Microstructures and Low-Temperature Impact Toughness of Medium-Carbon CrMo Alloy Steels with Different Quenching Temperatures

The effect of boron (B) on the microstructures and low-temperature impact toughness of medium-carbon CrMo steel quenched at 870~1050 °C and tempered at 600 °C was studied via Charpy impact testing and microstructure characterizations. The results showed that with an increasing B content from 0 to 50 ppm, the low-temperature impact toughness deteriorated significantly at quenching temperatures (Tq) lower than 950 °C but increased at a higher Tq of 1050 °C. Undissolved M2B particles remained and coarsened during the holding process due to the low Tq, decreasing the critical stress required for crack initiation and deteriorating the impact toughness accordingly. However, this detrimental effect of B could be mitigated by a higher Tq, and the favorable influences on the impact toughness improvement could be attributed to (1) the finer M2B particles formed during quenching effectively pinning the austenite grain boundaries (GBs), leading to a finer block size and a high density of high-angle grain boundaries, which reduced the critical stress for crack initiation; and (2) the fact that the coarsening of M23C6 on the GBs during tempering was slightly suppressed by the segregated B, eventually increasing the energy required for crack propagation. However, the degree of the favorable effect due to B was still lower than the negative effect of a high Tq.

Influence of Cr + Si content variation on cutting behavior of TiAlCrSiN HPPMS coatings

As high power pulse magnetron sputtering (HPPMS) technology is becoming popular in cutting tool industry, the development of nanocomposite coating systems such as TiAlCrSiN with this technology presents a new research avenue. Here, the combined effect of Cr and Si contents on properties and cutting behavior of high Al content TiAlCrSiN HPPMS coatings needs further investigation. For this purpose, three HPPMS coatings with Al/Ti ratio x = 1.4–1.5 and varying Cr + Si content, namely (Ti28Al40Cr16Si16)N, (Ti30Al43Cr17Si10)N and (Ti36Al54Cr5Si5)N, were deposited on cemented carbide substrates. In addition to basic characterization, the fracture behavior of the coatings was characterized by scratch tests. The cutting behavior of the coated inserts was exemplarily investigated during dry cutting of normalized medium carbon steel C45 with cutting speed vc = 80 m/min, feed rate f = 0.12 mm and cutting depth ap = 0.8 mm. The tool damage over the cutting time of tc = 35–40 min, as per the tool condition, was observed using light microscopy. Moreover, the damage mechanisms were analyzed in detail at the end of the cutting test using scanning electron microscopy. All coatings showed comparable indentation hardness HIT and indentation modulus EIT. However, an increased Cr + Si content amplified the brittle fracture of the coating under sliding load of scratch test. Moreover, the workpiece material C45 showed a higher adhesion tendency to cutting insert with high Cr + Si content TiAlCrSiN coatings during cutting tests. The tool wear and built-up edge formation increased due to the combined effect of workpiece adhesions and amplified brittle fracture of the coating at considered cutting speed. On the other hand, the inserts with low Cr + Si content coating exhibited better cutting performance and reduced built-up edge formation based on the improved fracture behavior of the coating and lower adhesion tendency of workpiece material to the corresponding coated insert.

Carbon Atom Distribution and Impact Toughness of High-Carbon Bainitic Steel

High-carbon nano bainitic steel is currently a hot research topic. The effect of the matrix’s carbon content and carbon atom distribution on the toughness of high-silicon, high-carbon bainitic steel is studied. The microstructure under an incomplete austenitization process consists of undissolved carbides, bainitic ferrite, and retained austenite. Using this process, the carbon content in bainitic ferrite is relatively low. Under the complete austenitization process, the carbon content in the bainite ferrite in the sample is high, and there is more retained austenite in the blocky type. The sample exhibits high impact toughness under an incomplete austenitization process, which is mainly affected by the low carbon content of bainite ferrite, high coordination ability of retained austenite, and high interface density of microstructure. The EBSD results show that the crack easily propagates between parallel bainite laths with low interface density compared with the high interface density perpendicular to the laths.

The significant impact of the crystallization of cementite in high carbon steel wire on its torsional performance

This article investigates the mechanism behind the significant differences in torsional properties of high carbon steel wire rods under two different drawing conditions when subjected to the same hot-dip galvanizing treatment. In our experiment, two types of drawn wires were annealed at 200–500 °C. X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy were used to comprehensively analyze the changes in ferrite lattice parameters, the dissolution of cementite, and the crystallization process under the two drawing conditions. The finite element method is used to simulate the strain in different drawing processes. The experimental results indicate that the wire subjected to less equivalent plastic strain shows good torsion ability during wire drawing, which is due to the slow crystallization process of cementite dissolved in ferrite during hot dip galvanization.

MODELING OF PHASE TURNING PID HOUR OF PERMANENT COOLING OF HIGH-CARBON ALLOYING STEELS

On the basis of the author's analytical model together with finite element models, simulation of phase transformations during continuous cooling of high-carbon alloyed steels, intended for the manufacture of metal products of responsible purpose, in particular for the metallurgical and machine-building industries, was performed. The simulation results are summarized by constructing thermokinetic diagrams of austenite decay in the process of continuous cooling of steels 65Cr3SiMoV, 80Cr3MoV, 80Cr5MoV. The obtained results will be used during the adjustment of industrial modes of heat treatment of metal products of responsible purpose, in particular, back-up rolls of rolling mills. At the next stage of research, it is advisable to construct isothermal and structural diagrams of steels 65Cr3SiMoV, 80Cr3MoV, 80Cr5MoV including the determination of the distribution of structural components according to the depth of the strengthened layer (0–100 mm), which will allow to create scientifically based principles for improving the technology of heat treatment of support rolls rolling mills, which are made of high-carbon alloy steels.

Modification of extended Oxley’s predictive machining theory and determination of Johnson-Cook material model constants by inverse approach

The Johnson-Cook (J-C) flow stress model, renowned for its consideration of the combined effect of strain, strain-rate, and temperature on material property, forms the cornerstone of this research. Its simplicity and applicability in numerical simulation render it widely popular. The study addresses two primary objectives: first, to modify extended Oxley’s predictive machining theory by eliminating the iterative loop for calculating the tool-chip interface temperature, and second, to utilize an inverse approach for determining J-C material model constants specific to medium carbon steel. The modified approach successfully eliminates the iterative loop, thereby streamlining the determination process and effectively reducing calculation time by 25%–40%, thereby enhancing overall efficiency. Concurrently, the study employs an inverse approach to accurately determine the J-C constants (A, B, n, C, and m). Notably, the research avoids the need for expensive and time-consuming Split Hopkinson Pressure Bar (SHPB) tests, instead opting for low-cost axial tensile tests and numerical optimization techniques to obtain the J-C constants. Thus, this study provides a practical method for determining J-C constants, pivotal for accurate material representation in numerical simulations and metal cutting applications. Standard materials and machines are employed, ensuring ease of understanding for a wider audience. The predicted values for the J-C constants are in proximity to the experimental values obtained by using SHPB test. Validated findings, achieved with precision under specified metal cutting conditions, highlight the effectiveness and applicability of the proposed approach, providing valuable insights for optimizing machining processes and improving efficiency.

MICROSTRUCTURE CHARACTERISTICS OF Cr3C2-NiCr COATINGS DEPOSITED WITH THE HIGH-VELOCITY OXY-FUEL THERMAL-SPRAY TECHNIQUE

With the goals of protecting boiler tubes from hostile surroundings, increasing thermal efficiency, and minimizing time losses from damage, thermal-spray coating methods for high-temperature operations were created. Ceramic-metal composite materials (e.g., Cr3C2-NiCr) are well known for protecting components from erosion decay in a high-temperature environment. In this investigation, the high-velocity oxy-fuel (HVOF) thermal-spray technique was employed to successfully deposit several variations of feedstocks containing Cr3C2-NiCr and NiCr powders onto a medium-carbon steel substrate, with and without filtering through a 400-mesh screen. Utilizing X-ray fluorescence (XRF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the microstructure features of the deposited coatings were assessed. The experiment results demonstrate that the crystallite and grain sizes of the deposited coatings can be increased by reducing the powder size through a sifting process using a 400-mesh sieve. This procedure also resulted in a coating with a higher density and lower porosity. Furthermore, new compounds including Cr2O3 and MnCr2O4 were formed in the coating layers as indicated by the XRD spectra. These phenomena are in good agreement with the EDS mapping of Cr and O, which reveals highly similar distributions. Manganese was originally a part of the substrate composition. Manganese could diffuse rapidly across the Cr2O3 layer and form the MnCr2O4 compound, indicating the manganese diffusion from the substrate into the Cr3C2-NiCr coating. The formation of MnCr2O4 can be attributed to the prior emergence of the Cr2O3 compound.