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The inhomogeneity present in the deformation and microstructure during the open die forging of large size ingot significantly influences the mechanical properties of the final part. This study aims to develop a microstructure-based finite element (FE) model and investigate the influence of deformation path on microstructure evolution during the upsetting process of large size ingot of a high strength steel. The difference in deformation path is achieved by modification in anvil shape such as flat, v shape, convex, and concave die. To achieve this goal, hot compression tests were carried out using the Gleeble 3800 thermomechanical simulator. Utilizing the acquired and corrected flow stress data, a material model and a microstructure model were established, and both formulated models were then integrated into the Forge NxT 3.2 finite element simulation software through the inclusion of a dedicated user subroutine. The predictions from the FE analysis were validated with experimental results on standard size hot compression specimens, which allowed for the accurate prediction of the dynamic recrystallized average grain size at the end of hot deformation. Afterwards, the validated FE model was scaled up to simulate the industrial upsetting process, making it possible to investigate the effect of deformation path on inhomogeneity of strain and microstructure evolution at the end of upsetting process for large sized forged ingots. An evaluative analysis of four die geometries, aimed at identifying the optimal die shape for minimizing inhomogeneity in strain and grain size across a large size forged ingot, was conducted. It was found that the convex die provokes the lowest deformation, while the concave die induces the highest deformation values at the center of the ingot. Utilizing the coefficient of variation as an indicator of heterogeneity, it was determined that the v-die and concave die resulted in a more consistent grain size distribution compared to the flat and convex dies. [ABSTRACT FROM AUTHOR]

Medium carbon steel is one of the most abundantly used materials globally due to its availability, low cost, and wide range of properties. On the other hand, medium carbon steel has a significant disadvantage in terms of corrosion and wear resistance. In this research work the medium carbon steel substrate is electroplated with ternary alloy Zn–Ni–W to improve the hardness and resistance to corrosion in the steel substrate. Providing a Zn–Ni–W alloy sacrificial thin layers with a trace amount of W on the surface of a mild steel substrate improves its corrosion and wear resistance. The electrolyte composition is optimized in such a way that the coating is rich in Zn which makes it a sacrificial type coating. The coating is done in an acidic sulfate bath with current density and pH of 1 A/dm2 and 5 respectively. The electrodeposition process is carried out at two different temperatures 55 °C and 70 °C with a deposition time of 30 min respectively. Surface morphology, chemical content, phase structure, and the thickness of these coatings are studied and compared using SEM, EDS, and XRD. Corrosion and wear behavior of Zn–Ni–W alloy coating has been done with the help of Electrochemical impedance spectroscopy (EIS). In conclusion, EIS results reveal notable characteristics for the Zn–Ni–W sample coated at 70 °C. The thin film exhibited a low corrosion rate and corrosion current, indicating a enhanced resistance against corrosion. Furthermore, the high polarization resistance value emphasizes the film's effectiveness in inhibiting corrosion processes. These findings collectively emphasize the favorable corrosion-resistant properties of the Zn–Ni–W coating deposited at 70 °C. [ABSTRACT FROM AUTHOR]

A comprehensive experimental study was conducted on EN8 steel samples subjected to hot rolling at various temperatures and with different numbers of passes. The research investigates the influence of these rolling parameters on the material's microstructure, hardness, and magnetic properties. The study includes controlled heating to specific temperatures, precise adjustments of roll spacing, and meticulous monitoring of rolling parameters. Key findings include the microstructural evolution during hot rolling, with grain refinement and phase transition, notably influenced by temperature. The data also reveals the relationship between rolling conditions, material hardness, and percentage of recrystallization, offering insights into optimizing material properties. Furthermore, the study presents an in-depth analysis of the Barkhausen peak's behavior concerning temperature, showcasing its potential for non-destructive hardness evaluation. Overall, this research provides valuable knowledge for material engineers and manufacturers aiming to tailor EN8 steel properties through optimized rolling and heat treatment processes. [ABSTRACT FROM AUTHOR]

The use of solenoid magnets in welding processes has attracted attention due to their potential to influence the properties of welded joints. This research investigates the effect of the size of the magnetic induction solenoid on the tensile strength and impact toughness of welds between mild steel and medium carbon steel. Welding experiments were carried out using various sizes of solenoid magnets (0; 1.71mT; 2.11mT; 2.31mT; 2.60mT), and the welding results were tested for tensile strength and impact toughness. The findings show that the size of the magnetic induction solenoid has a significant effect on the mechanical properties of the weld. The larger induction size in this study increased the tensile strength of the welded joint, namely 431.576 N/mm2 without induction and 533.33 N/mm2 with induction. Meanwhile, the impact toughness of welded joints also increases, namely 95.92N.m without treatment and 217.35N.m with induction. [ABSTRACT FROM AUTHOR]

In this study, the effect of rolling of 1.25Cr-1Mo-0.5V-0.3C American Iron and Steel Institute 4340 modified steel for highspeed railway brake discs on the microstructure and mechanical properties was investigated. The materials were hot-rolled at 0%, 51%, and 66% reduction ratios, and then analyzed by optical microscopy, scanning electron microscopy, and electron backscattering diffraction (EBSD). needle-shaped ferrite block morphology in bainite varied with the rolling ratio. EBSD analysis reveals dynamic recovery and dynamic recrystallization, affected ferrite block boundaries and dislocation densities during rolling. Mechanical tests showed that hardness, toughness and elongation increase at higher rolling reduction ratio, while strength remained relatively constant. In particular, the impact toughness increased almost twice from the level of 70 J in S1 (0% reduction) to the level of 130 J in S3 (66% reduction). These results showed that the hot rolling can significantly improve the strength and toughness combination of cast brake discs material.

Since it is known that tensile strength and hardness are roughly proportional, a hardness test is often used as a simple and substitute test. However, it has been reported that the proportional relationship between tensile strength and hardness is broken above 595 HV (≈55 HRC). Besides, there are few examples of mechanical properties determined by compression tests despite the fact that high-hardness and high-strength materials subjected to significant compressive stress are used in machine element parts, e.g. bearings. Tensile strength is used instead of compressive strength for the design. Thus, the relationship between hardness and compressive strength in hard materials, quenched medium carbon steel, was revealed. The compressive strength at 8% plastic strain (compressive strength) was almost the same as the maximum compressive strength. The compressive strength and hardness were at their maximum in the as-quenched specimen and decreased with the increase in tempering temperature. The compressive strength and hardness had a linear relationship up to 2000 MPa similar to the relationship of tensile tests. However, the compressive strength increased slightly in relation to the hardness above 2000 MPa in contrast to tensile tests. Thus, the work-hardening index was introduced as a variation parameter to the function that expresses the relationship between compressive strength and hardness to obtain better estimation. The estimated compressive strengths using the work-hardening index are agreed well to the experimental results.

In the present paper, the influence of the mean stress on the fatigue behavior of smooth and notched medium carbon steel components (C45 grade) is investigated through conventional and more advanced design methodologies. Original experimental data are provided for two notched specimen geometries and three different high load ratios (R = {0.7, 0.8, 0.9}). To assess the effect of the mean stress in a larger range, the bulk of fatigue data has been widened through more than 150 tests on C45 steel drawn from literature. The considered experimental data ranged between a load ratio of −2 and 0.9. The mean stress effect has been assessed in a first attempt through well‐established literature models resulting in a data correlation characterized by a large scatter. Finally, an attempt to uniquely consider both geometrical and load ratio effects has been performed through a numerical application of the strain energy density (SED) method. Elevated load ratios (R ≥ 0.7) prove to be highly detrimental for C45 steel with a fatigue life reduction of up to 3 orders of magnitude; however, this effect can be considered with a sufficient degree of accuracy through the SED method. Highlights: Original experimental fatigue data are provided for very high load ratio.Experimental fatigue results, having load ratio between −2 and 0.9, are considered.A comparison between different methodologies to account for load ratio is reported.A unique fatigue curve is achieved through an energetic local approach. [ABSTRACT FROM AUTHOR]

AISI 4130 steel is widely used in the aircraft industry, mainly for frame structures. It is a medium carbon low-alloyed (25CrMo4) steel predetermined for precipitation of carbides in the microstructure during heat treatment. Six different heat treatments were applied to study the effect of the resulting microstructure (ferritic-pearlitic in a normalised state or martensitic with carbides in a hardened state) on the fatigue life of AISI 4130. Tension-tension cycling under force control was used to determine the S-N curve of flat specimens with a central circular notch. The best fatigue properties were achieved for the material state HT125, i.e., hardened & tempered to 125 ksi (863 MPa), exhibiting the maximum stress at a fatigue limit of 225 MPa, which is approximately 5-15 % better compared to the rest of the applied heat treatments. Microstructural investigations using scanning electron microscopy explained the acquired fatigue life results of AISI 4130 concerning different heat-treated conditions. [ABSTRACT FROM AUTHOR]

The possibility of increasing the durability of steel pins working against bronze bushings through plasma–electrolytic nitrocarburizing of the surface of medium carbon steel is shown. The phase composition, microhardness, morphology, and surface roughness were studied. Tribological tests were carried out under dry friction conditions according to the shaft-pad scheme. It has been established that plasma–electrolytic nitrocarburizing of the surface of medium carbon steel at a temperature of 700 °C for 5 min leads to a decrease in the friction coefficient by 2.3 times, the weight wear of steel by 24.9 times, and the wear of the bronze counterbody by 5.9 times. At the same time, the contact stiffness increases by 2.6 times. Type of wear: wear with dry friction and plastic contact. The changes in tribological characteristics are associated with the high hardness of the hardened steel surface combined with the effect of dispersed nitrides and iron carbonitrides. [ABSTRACT FROM AUTHOR]

To ensure the high strength of 55Si2MnMoV steel and greatly improve the ductility, three samples with various initial microstructures (annealing, quenching, and austempering) were subjected to intercritical annealing (820 °C) and austempering (325 °C) for 25 min, respectively. The effects of the initial microstructure on the final microstructure and mechanical properties were systematically studied. XRD revealed that the volume of retained austenite (RA) of the three decreased significantly with the location close to the tensile fracture surface. While the conversion proportion of RA in the quenched sample peaked at 16.5%, indicating that RA transforms into martensite to a greater extent during tensile, thus delaying the occurrence of necking. The ferrite grains in the quenched sample were significantly refined and uniformly distributed, and a few were polygonal. Additionally, the grains of the austempered sample were mostly lath because of the inheritance of the initial microstructure. The ultimate tensile strength (UTS) of the quenched sample reaches 1093.61 MPa, which is slightly lower than that of the annealed sample, but the plasticity is greatly improved. The corresponding product of strength and elongation (PSE) reaches the peak value of 67.05 GPa%, which is 26.22% higher than that of the annealed sample, this is mainly attributed to the transformation of RA in a broad range of strain and the uniform equiaxed microstructure. Also, the strength ratio of the three samples fluctuates between 0.67 and 0.71, and their failure modes are all ductile fractures.

The effect of retained austenite stability on plastic deformation was investigated by stepwise tensile test of medium carbon steel material at two different bainite isothermal temperatures below or above the martensite start (Ms) point. The results show that higher retained austenite transformation leads to higher elongation. Compared with the above-Ms bainitic steel (320 °C-12 h), the below-Ms bainitic steel of retained austenite (240 °C-48 h) has higher mechanical stability. This is because the transformation induced plasticity effect (i.e., the TRIP effect) of retained austenite plays a significant role in the process of tensile strain. The block retained austenite distributed between the bainite sheaf deforms rapidly in the initial stage, and the film retained austenite between the bainitic-ferrite lath transformation is slow in the later stage of tensile deformation. This is attributed to the low stability of block retained austenite, which easily transforms into hard and brittle martensite under external stress, while the film retained austenite has high stability and cannot easily undergo phase transformation under the action of external force. Meanwhile, the work hardening ability of the below-Ms bainitic steel is higher than that of the above-Ms bainitic steel at the initial stage of tension, but the opposite occurs in the later stage of tension.

A new concept for the alloy design of advanced structural steels was figured out with the experimental elaboration of deformation behaviour in two novel medium carbon bainitic steels proposed sparse mixed regression model. Fe-0.53C-1.55Si-0.48Mn-0.59Cr-0.05Ni (wt%, Steel-A) and Fe-0.64C-1.74Si-2.11Mn-0.2Cr-0.15Ni (Steel-B) were studied. These steels were austempered to get bainite structure with retained austenite of different fraction and morphology. The chemical composition and heat treatment conditions were designed by sparse mixed regression modelling. In the Steel-A, the retained austenite fraction is 0.07 and it is in film form. In the Steel-B, the retained austenite fraction is 0.37 and most of them are in blocky form. Both the samples showed high tensile strength (>1.6 GPa) and good elongation (>12%). The Steel-A showed poor uniform elongation, but large post-uniform elongation. In the Steel-A, the retained austenite is stable during deformation, so inherent ductility of bainitic ferrite matrix largely contributed to higher post-uniform elongation. On the other hand, in Steel-B, the occurrence of deformation-induced martensitic transformation leads to large uniform elongation, through increasing the work hardening rate and delaying the onset of plastic instability.

Medium carbon steel is widely consumed by various industrial sectors due to its attractive set of mechanical properties and low cost, but it experiences deterioration when exposed to a corrosive environment. In the present study, Aloe Vera plant extract was studied as a green corrosion inhibitor for medium carbon steel in an acidic medium. The presence of inhibitive compounds in Aloe Vera plant extract was determined by FTIR. Moreover, the inhibition efficiency was determined through gravimetric analysis and electrochemical analysis. The results show that the Aloe Vera plant extract provided inhibition efficiency of more than 90% in both gravimetric and electrochemical analyses. Furthermore, the shift in polarization curves depicts that this plant extract is a mixed type inhibitor acting as an anodic and cathodic inhibitor. Overall, Aloe Vera plant extract provides excellent corrosion inhibition to medium carbon steel in the H2SO4 environment and can be used as a green corrosion inhibitor for mitigating internal corrosion of pipelines and storage tanks.

Studies on load capacity enhancement for an interference fit mainly focused on the essential coupling material pair of steel–steel parts. With more complex requirements in technical assemblies, more notable cases of material pairs are applied in interference fits. Hence, it is crucial to highlight the variations across-coupling scenarios in order to identify a workable approach for load capacity augmentation. The goal of this study is to examine how nickel plating affects the interference fit between steel and brass assembly parts. The experiments in this research focus on comparing the load capacity of plated and non-plated specimens by evaluating the extraction force on a compression machine. The fit parameters are measured with a coordinate measuring machine and contact surface profiler. Some microscopic observations are made to confirm the phenomena of this coupling case. The axial extraction tests determined that the plated fits show an increase in axial force limits of around 20% in comparison with the non-plated ones. There are also some significant improvements in the plated shaft surface properties, which reduce the physical adhesions between the shaft and hub. These results confirm the possibility of reusing the plated assembly parts, which gives highly economic and environmental advantages. [ABSTRACT FROM AUTHOR]

The effectiveness of acid solutions as a quenching agent for medium carbon steel and 5083-H22 aluminium alloy was investigated in this work. The samples were quenched in different acidic solutions. Solution A consists of 99% water +1% HCl, solution B consists of 97% water +3% HCl and solution C consists of 95% water +5% HCl. Thermal camera of type FLIR T600 was used to calculate the heat transfer time between the samples and the media. The microstructural characteristics of the quenched specimens were examined with an optical microscope. The mechanical properties such as yield strength, tensile strength, elongation and hardness were obtained by the conventional method. The results reveal that the samples quenched in solutions B and C show a significant increase in terms of strength compared to samples quenched in water. The accelerated cooling in solutions B and C has a double advantage which leads to an increase in the strength of the steel without a great degradation of the deformation properties, and that's what all mechanical engineers aspire. The obtained results on 5083-H22 aluminium alloy confirm the superiority of solutions B and C over water as a quenching agent in terms of strength, hardness and elongation. [ABSTRACT FROM AUTHOR]

In this study, the effects of corrosion rate on post welded annealed heat-treated medium carbon steel in seawater was investigated. The medium carbon steel samples were butt-welded by using the Shielded Metal Arc Welding (SMAW) technique and, afterwards, heat treated by annealing at different annealing temperature was carried out. The microstructure of the unwelded and post welded heated samples was characterised by means of optical microscopy. The as received (control), unwelded and post welded annealed medium carbon steel samples were immersed in sea water for a duration of one hundred (100) days, and this was to stimulate the effect on equipment in offshore and food processing applications. Post welded heat treatment on the microstructure, weight loss and corrosion rate were evaluated. The results obtained showed an initial increase in both the weight loss and corrosion rate of samples up to 40 days and started decreasing afterwards. It was equally observed that the post welded annealed samples showed more corrosion activities than the un-welded annealed samples. Above and beyond, corrosion activity was more prominent in samples with the highest annealing temperature. More so, the unwelded annealed medium carbon steel showed a dispersion of coalescence cementite and ferrite grain while the post welded annealed medium carbon steel samples showed a martensite (light area marked by arrows) distributed in the ferrite (dark area) matrix.

The possibility of increasing the durability of steel pins working against bronze bushings through plasma–electrolytic nitrocarburizing of the surface of medium carbon steel is shown. The phase composition, microhardness, morphology, and surface roughness were studied. Tribological tests were carried out under dry friction conditions according to the shaft-pad scheme. It has been established that plasma–electrolytic nitrocarburizing of the surface of medium carbon steel at a temperature of 700 °C for 5 min leads to a decrease in the friction coefficient by 2.3 times, the weight wear of steel by 24.9 times, and the wear of the bronze counterbody by 5.9 times. At the same time, the contact stiffness increases by 2.6 times. Type of wear: wear with dry friction and plastic contact. The changes in tribological characteristics are associated with the high hardness of the hardened steel surface combined with the effect of dispersed nitrides and iron carbonitrides.

Spring steels are typical materials where enhancement of mechanical properties can save considerable mass for transport vehicles, in this way the consumption of fuel or electric energy can be decreased. A drastic change in both the resulting microstructure and mechanical properties could be achieved due to the inclusion of strain into the tempering process after quenching. The strain assisted tempering (SAT) technology was applied, i.e., the process of quenching and following a sequence of tempering operations alternating with strain operations. After the first tempering, controlled deformation by rotary swaging was carried out with a strain of 17% (strain rate is about 120 s−1). Considerably higher strength parameters after SAT compared to conventional quenching and tempering (QT) technology were nevertheless accompanied by enhanced notch toughness at the same time by the decrease of elongation and reduction of area. However, by optimizing the process it is was also possible to achieve acceptable values for those parameters. Remarkable differences are visible in resulting microstructures of compared samples, which were revealed by metallographic analysis and X-ray diffraction measurement. While the standard microstructure of tempered martensite with transition carbides was observed after QT processing, carbideless islands with nanotwins occurred in martensitic laths after SAT processing. [ABSTRACT FROM AUTHOR]

The surface cracking problem in medium carbon sulfur‐containing steel is gradually emerging in continuous casting production. Therefore, this article investigates the effect of sulfur content on the surface cracks of medium carbon steel. In addition to macroscopic cracks, network cracks are visible on the surface of medium carbon sulfur‐containing bloom. 3D confocal laser scanning microscopy and industrial computed tomography are used to characterize the 3D realistic morphology of the network and macroscopic cracks. Thermodynamic calculations and hot ductility tests' results exhibit the higher precipitation of MnS in the sulfur‐containing steel, resulting in the second brittle zone of steel. The microstructure near the cracks revealed a high correlation between cracks and a high proportion of proeutectoid ferrite near the surface of the medium carbon sulfur‐containing bloom. In addition, the sulfur‐containing steel has 0.05% more linear shrinkage than the low‐sulfur steel during the transformation from austenite to ferrite, which increases its crack sensitivity. As a result, this article clarifies the effect of sulfur on the surface crack of medium carbon bloom. [ABSTRACT FROM AUTHOR]

Distinct materials are used for the construction of battle tanks used in defense sectors. The hull and turret of the battle tanks are made up of rolled homogeneous armor steel (also known as armor steel). The inner portions like the driver cabin and control room are covered with medium carbon steel. Hence, the dissimilar joint between these materials is unavoidable in the battle tank construction. Conventional fusion welding processes like manual metal arc welding, gas metal arc welding, and gas tungsten arc welding are preferred to join the dissimilar metals. However, the high heat input nature of these processes will create hydrogen induced cracking, high residual tensile strain, and HAZ softening, etc. To minimize these issues, solid state welding processes were adopted. In the present study, mechanical properties and microstructural characteristics of rotary friction welded dissimilar joint of armor steel and medium carbon steel was analyzed. The ultimate tensile strength of the dissimilar joint is around 775 MPa and the failure occurred at the medium carbon steel side. The impact toughness value of dissimilar joints is higher than medium carbon steel and lower than armor steel. The microstructure across the dissimilar joint has distinct features and a complex pattern was observed at the weld interface.

A heterogeneous microstructure composed of multiscale ferrite (spanning ultrafine, fine, and coarse grains) and granular or short rod cementite was obtained by warm rolling pseudoeutectoid microstructure. Combined with the short-time annealing process, the deformation tendency of ferrite grains and the dissolution and precipitation of cementite were adjusted. The mechanical properties of medium carbon steel are close to that of low alloy high strength steel. It was found that the GNDs are distributed in a gradient at the interface of the soft domain, and the closer to the boundary the higher the density, which contributes to the occurrence of the hetero-deformation induced (HDI) hardening mechanism and provides additional strength and plasticity. The increase in elongation of the annealed samples is due to the recrystallization of ferrite and the redistribution of cementite, which realizes the combination of HDI mechanism, Orowan strengthening and annealing softening mechanism. Additional strengthening mechanisms are calculated and a physical model of cementite ripening during annealing is proposed. The tensile fracture shows that the cracks mainly propagate along the grain boundaries of the layered microstructure, and the high density of dimples can make the propagation path of the cracks tortuous and increase the elongation.

Medium carbon steel is widely consumed by various industrial sectors due to its attractive set of mechanical properties and low cost, but it experiences deterioration when exposed to a corrosive environment. In the present study, Aloe Vera plant extract was studied as a green corrosion inhibitor for medium carbon steel in an acidic medium. The presence of inhibitive compounds in Aloe Vera plant extract was determined by FTIR. Moreover, the inhibition efficiency was determined through gravimetric analysis and electrochemical analysis. The results show that the Aloe Vera plant extract provided inhibition efficiency of more than 90% in both gravimetric and electrochemical analyses. Furthermore, the shift in polarization curves depicts that this plant extract is a mixed type inhibitor acting as an anodic and cathodic inhibitor. Overall, Aloe Vera plant extract provides excellent corrosion inhibition to medium carbon steel in the H2SO4 environment and can be used as a green corrosion inhibitor for mitigating internal corrosion of pipelines and storage tanks. [ABSTRACT FROM AUTHOR]

The hot coil slump is a recurrent problem in the manufacturing process of medium and high equivalent carbon steel plates. Even with the success of the hot rolling procedure, the posterior coil slump can occur, representing operational disorder and manufacturing cost increase. Some authors point that the coil slump phenomenon can occur due to metallurgical, mechanical and geometric aspects. Preview studies already investigated several possible mechanical and geometric contributions. However, there are few available experimental data about the metallurgical one, that is, the effect of late austenite decomposition during, or after the coiling stage. In this context, this paper presents a study about the application of dilatometry technique aiming to evaluate the influence of late phase transformations as a relevant cause of a medium carbon steel coil slump. Heating cycles that simulated, with good agreement, some possible plate cooling conditions and isothermal coiling procedures were performed in standardized specimens using a quenching dilatometer. Different combinations of cooling rates and coiling temperatures were evaluated. It was possible to conclude that the dilatometry technique application is viable and efficient to evaluate the metallurgical contribution to the coil slump phenomenon. For the studied steel, it was possible to suggest that a decrease of the cooling rate, in association with a slight decrease of coiling temperature, can significantly suppress the metallurgical influence on the coil slump occurrences. [ABSTRACT FROM AUTHOR]

Medium carbon steel is widely consumed by various industrial sectors due to its attractive set of mechanical properties and low cost, but it experiences deterioration when exposed to a corrosive environment. In the present study, Aloe Vera plant extract was studied as a green corrosion inhibitor for medium carbon steel in an acidic medium. The presence of inhibitive compounds in Aloe Vera plant extract was determined by FTIR. Moreover, the inhibition efficiency was determined through gravimetric analysis and electrochemical analysis. The results show that the Aloe Vera plant extract provided inhibition efficiency of more than 90% in both gravimetric and electrochemical analyses. Furthermore, the shift in polarization curves depicts that this plant extract is a mixed type inhibitor acting as an anodic and cathodic inhibitor. Overall, Aloe Vera plant extract provides excellent corrosion inhibition to medium carbon steel in the H2SO4 environment and can be used as a green corrosion inhibitor for mitigating internal corrosion of pipelines and storage tanks. [ABSTRACT FROM AUTHOR]

The work presented in this paper is to investigate the wear rate and wear mechanism of medium carbon steel with carbon contents of about 0,5 wt.% under the friction load with various contact surface temperatures. The wear test was performed by using the linear reciprocating ball-on-flat wear test machine. To develop the elevated temperature on the surface of the wear test specimen, the heater assembled into the wear test machine. The surface temperature of the wear specimen was set in the range of 30 ºC up to 250 ºC. The test was taken under 5000 cycles of friction loading with a maximum of the normal load of 25N. The experiment results show that the change in the contact surface temperature in the range of 30 ºC up to 250 ºC causes the wear rate to increase slightly. This is because the elevated temperature at the surface was not high enough to cause the hardness of the material to decrease significantly. The worn surface looks very thin scratches and slightly deformed layers, and the wear mechanism had identified as oxide wear.

Medium carbon steel is commonly used in waterfront structures, i.e., ports, and piers, where it is surrounded by very aggressive environmental conditions. Thus, it is very susceptible to different forms of corrosion. This work proposed an artificial neural network (ANN) model to predict corrosion rate of tempered medium carbon steel in environmental conditions close to these conditions where it is commonly used. Tafel analysis was used to determine the corrosion rate of the heat-treated samples. Optical microscope was used also to examine the morphology of the surface after tempering process. Eleven different tempering temperatures between 400 to 600°C, and three holding times 45, 90, 135 min were selected. Over the whole set of experimental data, the results show that the proposed ANN can achieve an excellent classification accuracy of around 92.63%. Therefore, the proposed model has promising potential application to predict medium carbon steel corrosion at different tempering conditions. [ABSTRACT FROM AUTHOR]

The present study is aimed to eliminate the undesirable microstructure in the real working condition of the steel unit. In this work, the microstructure of hot-rolled medium carbon steel (grade 45C8) is studied for application in the automotive industry. The effect of the temperature and rolling rate on the microstructure has been thoroughly investigated by analyzing the microstructure containing ferrite and pearlite phases after each trial run of hot-rolled steel. The desired microstructure of fine ferrite and pearlite is very much essential in hot-rolled medium carbon steel for better strength and uniform properties of the material. The formation of coarse pearlite is undesirable, which may lead to breakage during drawing and hardness variation in the hot-rolled steel. Therefore, this study is focused to find the optimum condition for achieving the microstructure containing uniform distribution of fine pearlite and ferrite without the presence of blocky pearlite patches. [ABSTRACT FROM AUTHOR]

Improving wear resistance and reducing the coefficient of friction of the cylinder liner are critical to improving the service life and energy savings of internal combustion engines. In this paper, the effect of the characteristics of cementite precipitation on the tribological performance was studied using a medium carbon steel (AISI 1045 steel), which can be used to make cylinder liners. Three kinds of microstructures with different characteristics of cementite were obtained by heat treatments. Abrasive wear tests and dry sliding friction tests were conducted on the samples of each microstructure. The study indicated that the abrasive wear resistance of medium carbon steel mainly depends on its hardness rather than on the characteristics of cementite precipitation. However, increasing the hardness alone did not guarantee improvement of the dry sliding friction performance of medium carbon steel. The specimen with a spherical pearlite microstructure, which was granular cementite distributed in the ferrite matrix showed the best friction performance. Moreover, the abrasive wear mechanism and dry sliding friction mechanism were discussed. In the end, the correlation between the characteristics of cementite and tribological behavior was established. These findings can help develop multiphase materials with outstanding tribological performance. [ABSTRACT FROM AUTHOR]

In this study, the effects of corrosion rate on post welded annealed heat-treated medium carbon steel in seawater was investigated. The medium carbon steel samples were butt-welded by using the Shielded Metal Arc Welding (SMAW) technique and, afterwards, heat treated by annealing at different annealing temperature was carried out. The microstructure of the unwelded and post welded heated samples was characterised by means of optical microscopy. The as received (control), unwelded and post welded annealed medium carbon steel samples were immersed in sea water for a duration of one hundred (100) days, and this was to stimulate the effect on equipment in offshore and food processing applications. Post welded heat treatment on the microstructure, weight loss and corrosion rate were evaluated. The results obtained showed an initial increase in both the weight loss and corrosion rate of samples up to 40 days and started decreasing afterwards. It was equally observed that the post welded annealed samples showed more corrosion activities than the un-welded annealed samples. Above and beyond, corrosion activity was more prominent in samples with the highest annealing temperature. More so, the unwelded annealed medium carbon steel showed a dispersion of coalescence cementite and ferrite grain while the post welded annealed medium carbon steel samples showed a martensite (light area marked by arrows) distributed in the ferrite (dark area) matrix. [ABSTRACT FROM AUTHOR]

Ballistic resistant materials are materials containing right combination of hardness, strength, and toughness. The quench process produces high hardness and tensile strength but decreases toughness. The hardening process has been performed using an induction machine and a tempering process on a medium carbon steel plate. This work aimed to determine and analyze the effect of deep cryogenic treatment (DCT) on steel plates that have been quenched tempered. This research utilized steel plates of 130 x 130 x 8 mm size which has been quenched and then immersed in liquid nitrogen at a temperature of -196°C for 1, 5, 10, and 20 days. The micro Vickers hardness test specimen, tensile test and charpy impact test were made to determine the effect of immersion time. The test results and analysis showed that DCT had the ability to change microstructure, improve the hardness, tensile strength, and impact toughness. Furthermore, the maximum hardness was obtained during the immersion treatment of 20 days, which was 449.45 VHN and 1107.53 MPa, respectively. However, the highest toughness was obtained during the immersion of 10 days, which was 1,001 J/mm². In order to get the optimal combination of ballistic characters, further ballistic testing is needed, both in simulation using the finite element method and ballistic experiment test. [ABSTRACT FROM AUTHOR]

Experiments were conducted to study the effect of quenching medium carbon steel in water-based MWCNTs nanofluids at 0.05 % wt. concentration quenchant, a large cylindrical sample with 46 mm diameter and 40 mm length made from medium carbon steel used with three K-type thermocouples with a diameter of 1.5 mm inserted in three locations for sample (center of the sample, mid-point between center and surface and 1 mm from the surface). A time-temperature reading data system was used to read temperature history during cooling stage. The same experiments were simulated using ANSYS Workbench with Thermal Transient Version 19, the cooling curves at three locations for the cylindrical steel sample calculated during quenching in MWCNTs nanofluids. Quench factor analysis was used to predict the hardness results from the calculated and measured cooling curves, and these results compared with the hardness test results conducted in the significant sample from the center to the surface. The results show excellent compatibility when compared between the hardness results from cooling curves, and it also shows a good agreement with the results of the hardness test, especially at the sample surface.

Studies on load capacity enhancement for an interference fit mainly focused on the essential coupling material pair of steel–steel parts. With more complex requirements in technical assemblies, more notable cases of material pairs are applied in interference fits. Hence, it is crucial to highlight the variations across-coupling scenarios in order to identify a workable approach for load capacity augmentation. The goal of this study is to examine how nickel plating affects the interference fit between steel and brass assembly parts. The experiments in this research focus on comparing the load capacity of plated and non-plated specimens by evaluating the extraction force on a compression machine. The fit parameters are measured with a coordinate measuring machine and contact surface profiler. Some microscopic observations are made to confirm the phenomena of this coupling case. The axial extraction tests determined that the plated fits show an increase in axial force limits of around 20% in comparison with the non-plated ones. There are also some significant improvements in the plated shaft surface properties, which reduce the physical adhesions between the shaft and hub. These results confirm the possibility of reusing the plated assembly parts, which gives highly economic and environmental advantages.

Spring steels are typical materials where enhancement of mechanical properties can save considerable mass for transport vehicles, in this way the consumption of fuel or electric energy can be decreased. A drastic change in both the resulting microstructure and mechanical properties could be achieved due to the inclusion of strain into the tempering process after quenching. The strain assisted tempering (SAT) technology was applied, i.e., the process of quenching and following a sequence of tempering operations alternating with strain operations. After the first tempering, controlled deformation by rotary swaging was carried out with a strain of 17% (strain rate is about 120 s−1). Considerably higher strength parameters after SAT compared to conventional quenching and tempering (QT) technology were nevertheless accompanied by enhanced notch toughness at the same time by the decrease of elongation and reduction of area. However, by optimizing the process it is was also possible to achieve acceptable values for those parameters. Remarkable differences are visible in resulting microstructures of compared samples, which were revealed by metallographic analysis and X-ray diffraction measurement. While the standard microstructure of tempered martensite with transition carbides was observed after QT processing, carbideless islands with nanotwins occurred in martensitic laths after SAT processing.

The triboelectrification behavior of metal friction pairs is a crucial area of research for understanding the friction and wear. In this study, the triboelectrification behavior of surface nanocrystallization of medium carbon steel was investigated. Friction and wear tests were performed using a spherical-on-disc tribometer under oil-free lubrication while measuring triboelectric current signals. The results demonstrated that microstructural differences in chemically identical materials give rise to distinct charging behavior. In particular, nanocrystalline medium carbon steel surfaces exhibited significantly lower triboelectrification properties compared to their original surfaces. The main reason for the different triboelectrification behavior of the nanocrystalline medium carbon steel surfaces was attributed to the lattice distortion of nanospheres, which was explained using the theory of work function. And the underlying mechanism was experimentally verified using a D/max-Ultima+ X-ray diffractometer to measure the lattice distortion of nanospheres in medium carbon steel. Moreover, the study found a correlation between triboelectric current, friction coefficient, and loads. The findings of this study provide valuable insights into the role of surface microstructure in the friction and wear of materials. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine how the chemical composition and microstructure formed in medium carbon steel hardened with banana tree sap fluid compared to oil and water. The process of carbon steel hardening is being heated to the austenite area (850oC ) then held for 10 minutes after which it is cooled quickly (quenching). During the cooling process, it is also measured the cooling rate of the three cooling media. Hardening process material is carried out by microstructure observation using an optical microscope with 400x magnification and also chemical composition testing with SEM-EDX. The results for measuring the cooling rate of banana fluid have a fast cooling rate of 36.9oC/s while water is 16.6oC/s and oil is 7.0oC/s. In observing the microstructure of water it has an unstable micro structure that is still the structure of pearlite, this is because the temperature of the cooling media is too high during quenching. And for oil microstructure and banana fluid get a homogeneous structure, namely martensite and bainite. From the results of testing the chemical composition, it was seen that there was an increase in carbon content in steel after hardening and quenching with the three cooling media. Conclusion The hardening process by quenching oil and banana fluids has a homogeneous micro structure compared to water. Water cooling process has the highest carbon content increase of 1.53 %C from before 0.52 %C.

Abstract This paper investigated the effect of soft reduction amount increasing from 1-4mm with a cooling time of 120s and 180s to reduce the internal crack defects by analyzing the microstructure, crack morphology, extent and nature of grain boundary ferrite, centre macrosegregation, and fracture surfaces in medium carbon steel. It was found that the large extent of grain boundary ferrite with coarse morphology weakens the bonding force of the PAGB and makes it brittle with the initiation of micro-cracks. The sever centre carbon macrosegregation of 1.3 takes place at cooling time of 180s with different reduction amounts, which becomes homogeneous at cooling time of 120s. The results show that the length of inter-granular and trans-granular cracks reaches 20mm with the carbon macrosegregation index of 1.3. The carbon macrosegregation index of 1.3 with a small fraction of 15% is enough to deteriorate the centre macrostructure of the ingot. The cleavage facet size of fracture surfaces is remarkably decreased below 100um at soft reduction parameters of 2mm/120s, 3mm/120s, and 4mm/120s with micro-cracks less than 100um, which reveals that the microstructure of specimens with these soft reduction parameters is more resistant to the cracks propagation.

Improving wear resistance and reducing the coefficient of friction of the cylinder liner are critical to improving the service life and energy savings of internal combustion engines. In this paper, the effect of the characteristics of cementite precipitation on the tribological performance was studied using a medium carbon steel (AISI 1045 steel), which can be used to make cylinder liners. Three kinds of microstructures with different characteristics of cementite were obtained by heat treatments. Abrasive wear tests and dry sliding friction tests were conducted on the samples of each microstructure. The study indicated that the abrasive wear resistance of medium carbon steel mainly depends on its hardness rather than on the characteristics of cementite precipitation. However, increasing the hardness alone did not guarantee improvement of the dry sliding friction performance of medium carbon steel. The specimen with a spherical pearlite microstructure, which was granular cementite distributed in the ferrite matrix showed the best friction performance. Moreover, the abrasive wear mechanism and dry sliding friction mechanism were discussed. In the end, the correlation between the characteristics of cementite and tribological behavior was established. These findings can help develop multiphase materials with outstanding tribological performance.

A slurry pot has been designed, fabricated and evaluated for erosion-corrosion investigations. A variable voltage controller was used to vary the input voltage into the one-horse-power motor that controls the slurry pot. The actual speed of the slurry pot shaft was also calibrated using a non-contact digital tachometer. Voltages of 100 and 200 V resulted in rotational speeds of 1100 and 2100 rpm, respectively employed for the subsequent erosion-corrosion tests. Erosion-corrosion of a dual-phase carbon steel was investigated with the aid of the slurry pot in aerated 3.5 wt.% NaCl environments. The sample was normalised at 850 oC and then cooled in air to room temperature. Prior to the test, the normalised samples were heated to 700, 725, 750, 775, 800 and 825 oC, respectively and quenched in oil. Erosion-corrosion rates of between 0.027 to 1.26 g/cm2.hr at 1100 rpm and 0.57 to 1.9 g/cm2.hr at 2100 rpm were recorded. It was also observed that as hardness increased there was reduction in weight loss of the heat treated alloy.

Brazing is one of the most important techniques known in joining two similar/dissimilar metals/metal–nonmetal combinations for structural, mechanical, and aerospace applications. Brazing joints are formed by melting pure or alloyed foil called braze. Braze is melted in between the two substrates to be joined, and the joint is formed due to inherent adhesion and reactivity between braze and substrate. Copper and nickel are most commonly used brazes in the industry. Copper behavioral studies are mostly aimed at stainless steels (SS), and lot of research is carried out in Cu–SS systems. But, what is the copper behavior with medium carbon steels? What is the grain boundary behavior of copper and its mechanism when the alloying elements in steel are very low? Sandwich experiments were conducted with C45/Cu/C45 systems under an inert gas environment at 1100 °C. Cu was found to be wetting and penetrating the grain boundaries of medium carbon steel such as C45. The depth of penetration varied depending on holding times. The microstructure of the interface was characterized by SEM, and penetration depth was measured by image analysis software for better resolution and accuracy.