Mechanical Properties Of Carbon Steel Research Articles

Effect of Different Tempering Media on Fracture Toughness and Mechanical Properties of Carbon Steel

In this study, the effect of different thermal carbons on the impact resistance of heavy carbon, which contains 0.4% of. The focus was on how the resulting biochemistry affects the microstructure of the steel, and thus its mechanical properties. Steps: Impact test before heat treatment: Charpy impact test was performed on pre- impact specimens before any specimen was made. This test helps to determine the original impact of the steel without any modification in its microstructure. Tempering procedure: After that, it was further investigated by exposing it to high temperatures and then cooling it rapidly. This method is for market formation, which is a must. It was retested after tempering. The results showed a significant increase in the shock cases after tempering due to the formation of the texture which increased the strength of the specimen. Flame tempering (surface heat treatment): In this type of treatment, only the surface is heated with a flame and cooled rapidly, which results in the formation of a strong martensite texture on the surface, while the core of the specimen remains softer. When tested, it did get shock, but the amount of increase that occurred with full shock was not reduced. The reason for this is that the hardening in God is only on the surface while the core of the eye remains flexible, which leads to a reduction in contrast. Carburizing (surface heat treatment): Carburizing treatment is performed on some samples, which is a method that involves adding carbon to the outer surface of the fulminate and cooling it rapidly, resulting in a solid, hard material. When performing the shock test, it did get a shock that improved, but a case like flame hardening, you did not have very many shocks in full hardening.

Mechanical properties of carbon steel under uniaxial static tension

With the continuous development of science and technology, carbon steel is widely used in production and life. Especially at the practical application level, in the engineering application, the analysis of the mechanical properties of carbon steel materials has become increasingly prominent. The tensile test is a mechanical property test in which a standard tensile specimen is pulled to fracture at a specified tensile speed under the continuous action of static axial tensile force. The force and elongation are continuously recorded during the tensile process so as to obtain its strength criterion and plasticity criterion. In this paper, the characteristics of mechanical properties of the high, medium, and low carbon steels under uniaxial static tension are discussed. The reasons for the different mechanical properties of steels with different carbon content are explained from a microscopic perspective. The study provides some basic assistance to those who need relevant information.

An optimized machine-learning model for mechanical properties prediction and domain knowledge clarification in quenched and tempered steels

Clarifying the relationship between compositions, heat treatment processes, and mechanical properties of carbon steel, as the basis of material design, is challengeable, while machine learning (ML) makes this complex correlation explicit. In this work, three different mechanical properties (ultimate tensile strength, yield strength, and total elongation) were predicted based on the collected quenched and tempered (Q&T) steel dataset by six ML algorithms, in which the optimal Gaussian process regression (GPR) combined with the key descriptors by feature engineering to train an optimized ML model. Such a simplified ML model shows even better prediction accuracy. In the above training process, Bayesian optimization (BO) searches the hyperparameters efficiently. The newly collected data also achieve small prediction errors, showing good generalization capacity. To maximize the application value of the current ML model, the grid prediction of composition and process, and local interpretable model-agnostic explanations (LIME) were utilized to reveal some new insights about the quenched and tempered steels, which could shed light on the ongoing new material design. Besides, the overfitting tendency of the ML model was examined to ensure the rationality of prediction, and the influence of data amount on the prediction performance was discussed.

Data Science to Determine Mechanical Properties of Low Carbon Steel During In-Process Inspections

Carbon steel is a widely used category of engineering metal, mainly due to its attractive mechanical and fabrication properties and low cost. The chemical composition, physical parameters, and mechanical properties of carbon steel are maintained as per the specified standards, and local steel should be complied with Sri Lankan Standard 375: 2009. Generally, the chemical composition is tested during melt stages, and mechanical properties are tested for finished products. Since it is necessary to ensure products comply with the standard, mechanical properties are tested during in-process inspections as well. When the results are not within the acceptable range, a considerable amount of production has to be rejected, causing a loss to the manufacturers. If the results of the in-process inspection are instant, it will help make suitable adjustments to process conditions and thereby prevent rejection of products, while reducing quality assurance costs, as well. Therefore, the objective of this study is to predict tensile properties with chemical composition, as input variables, to be used for in-process inspections. Forty mechanical test reports were collected from a steel manufacturing factory for 12 mm diameter, thermo-mechanically treated (TMT) steel bars. Each test report is of 15 samples from the respective batch, and consists of corresponding chemical composition and physical parameters. Multiple linear regression analysis was applied to each batch, using Statistical Package for the Social Sciences (SPSS) software, to predict yield strength (YS), ultimate tensile strength (UTS), elongation at break (EB) with carbon equivalent value (CEQ) and percentage of Sulphur as inputs. Relationships between variables were not significant, even though those relationships can be used to predict tensile properties. The predictions may not be reliable, due to the limited conditions of the study and assumptions made. It is therefore recommended to apply multivariate regression analysis or Artificial Neural Network (ANN) techniques, with other chemical elements, process temperature and water flow rate etc. also as input variables. KEYWORDS: Chemical composition, In-process inspection, Low carbon steel, Multiple linear regression analysis, Tensile properties

Mechanical properties of corroded carbon steel based on random pit corrosion in marine environment

The corrosion of carbon steel seriously affects the long-term performance of the marine infrastructure. This study introduces an innovative numerical method for predicting the mechanical property degradation of carbon steel in the marine environment. To determine the degradation pattern of mechanical properties of carbon steel with various degrees of corrosion, 48 Q235 carbon steel specimens were subjected to mechanical properties testing after corrosion; a corrosion model with the stochastic distribution of corrosion pits was established based on the Monte-Carlo principle, and finite element analysis was carried out on the mechanical properties of carbon steel after corrosion. The numerical analytical results agreed well with the testing results, proving the model's validity and predicting the mechanical properties of carbon steel at various exposed times. The results demonstrate that as the amount of time exposed to specimens rises, the yield and tensile strength of the specimens decrease dramatically. Comparing the numerical simulation with the testing, the average error of the nominal tensile strength is 4.2%, and the average error of the nominal yield strength is 6.4%. It was further predicted that the specimens' nominal yield strength and nominal tensile strength decreased by 25.57% and 30.86% when the exposed time was 400 days.

A strategy assisted machine learning to process multi-objective optimization for improving mechanical properties of carbon steels

• Feature selection can effectively screen out the key materials descriptors related to tensile strength and elongation, respectively. • An effective method is proposed to deal with the two mutually exclusive properties for simultaneously optimizing the mechanical properties of carbon steel. • The established machine learning prediction model for the comprehensive performance of carbon steel has good generalization ability and is combined with the EGO algorithm to obtain the optimal carbon steel composition to guide the next experiment. Improvement in individual mechanical properties of carbon steels, such as strength or ductility, can no longer keep up with the increasingly demanding service environment. Therefore, it is of practical significance to improve two or more mechanical properties accurately and efficiently. In this work, five machine learning algorithms are first employed to establish prediction models for different mechanical properties (tensile strength, fracture strength, Charpy absorbed energy, hardness, fatigue strength, and elongation) based on the collected carbon steels data. Then, a set of mutually exclusive properties (tensile strength and elongation) and the key descriptors of the corresponding properties are identified by feature engineering, and the importance of the key materials descriptors is analyzed. The prediction models based on key descriptors for tensile strength and elongation also demonstrate good accuracy. All the key descriptors are considered as input features for the comprehensive performance (CP) calculated from the product of tensile strength and elongation. Finally, we develop a machine learning prediction model for CP and successfully apply the efficient global optimization algorithm to optimize two mutually exclusive mechanical properties. This work provides a new multi-objective optimization strategy that is expected to be used for the development of new steels with excellent comprehensive performance.

Evaluation of Tribological and Mechanical Properties of Carbon Steel with Fluoroligomeric Film at Piezoelectric Actuator Contact

The tribological investigations of carbon steel surfaces modified with fluoroligomeric materials were performed. Compared with the uncoated steel, the fluoroligomeric coated surface showed higher plasticity of the modified surface in the scratch tests where the fluoroligomeric film was not destroyed by higher loading. This could be explained by the lower micro hardness of the steel after processing by fluoroligomer and the influence of the adsorbic Rebinder effect. This study includes original results of the loading influence on the efficiency of the piezoelectric actuator and the wear value of the frictional element, which is important explaining the greater longevity of the piezoelectric actuator. Fluoroligomer treatment of the surface considerably improved the performance of the piezoelectric actuator. Using the reference steel roller in the piezoelectric actuator under minimum loads was characterized by a decrease in rotor speed with increasing the pressing of the frictional element. When the rotor was coated by fluoroligomer, the speed remained stable when increasing the pressing force. Using the reference steel roller, the rotation after short-term overloads was not restored, and rollers with fluoroligomeric surface started to rotate soon as the short-term overload was removed. The higher efficiency of piezoelectric actuators with a fluoroligomeric layer on the roller is related to almost two times lower wear of a friction element operating with coated rollers as compared to reference rollers.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ СКОРОСТИ ДЕФОРМАЦИИ НА СКЛОННОСТЬ УГЛЕРОДИСТОЙ СТАЛИ У8 К ДЕФОРМАЦИОННОМУ СТАРЕНИЮ

The effects of the strain rate and degree on the scale of the strain aging effect in carbon steel U8 with lamellar pearlite microstructure, which is a eutectoid mixture of ferrite plates and brittle plates of secondary cementite Fe3C have been investigated. The microstructure and properties of Russian steel U8 after quasistatic compression, dynamic compression (shock processing), and explosion processing have been investigated. A low-temperature annealing (150–500 °C) of the non-deformed steel U8 has been shown to result in a monotonous reduction of hardness. The quasistatic compression and shock processing of the carbon steel were found to result in the strain aging manifested as an increasing hardness at annealing of the deformed steel U8. The increasing of the deformation degree and strain rate was accompanied by the increasing of hardness of the annealed steel. The explosion treatment was shown not to result in a notable improvement of the mechanical properties of carbon steel as well as in a change of the morphology of cementite plates. The deformation aging effect in steel U8 after the explosion loading was absent. The strain aging effect in U8 steel after quasistatic compression and dynamic loading was suggested to originate from an increasing of the lattice dislocation density, the long-range internal stress fields from which lead to the dissociation of the cementite Fe3C plates and to increasing of the concentration of carbon atoms in the ferrite crystal lattice. The absence of the strain aging effect in the carbon steel after the explosion loading is due to a small degree of the explosion deformation that doesn't allow providing an essential increasing of the lattice dislocation density in ferrite.

Investigation of Heat Treatment on Mechanical Properties of Medium Carbon Steel

The effect of various heat treatment operations (annealing, normalizing and hardening) on mechanical properties of medium carbon steel was investigated. The samples were prepared and heat-treated at 770 ºC subsequently was cooled by different quenching media. The mechanical properties of the treated and untreated samples were determined using standard methods. Results showed that the mechanical properties of carbon steel can be changed and improved by various heat treatments. It was also found that the annealed samples has the lowest tensile strength and hardness value and highest ductility, while hardened samples has the highest tensile strength and hardness value and lowest ductility value.

Effect of Quenching on the Mechanical Properties of Carbon Steel for Hammer Mill

This paper covers the effect of quenching on the mechanical properties of high carbon steel for hammer mill. The main objective of this study is to investigate the mechanical properties and microstructure of high carbon steel before and after heat treatment (i.e., quenching). In this study, the specimens were heated at different level temperature which are 750 °C,800 °C and 900 °C prior to quenching process in water with soaking time of 5 minutes. After the heat treatment of quenching process completed, Rockwell hardness test and tensile test were performed, and the results were collected for both untreated and heat-treated specimens. The fractured surfaces of the specimens were also examined by using metallurgical microscope. It was observed that different level of quenching temperature and untreated specimens gave different mechanical properties. The specimen undergone water quenching recorded the highest hardness and tensile strength as 67.9 HRA and 426.11 MPa, respectively. Besides, the microstructure obtained from untreated specimen provided a good combination of ferrite and pearlite, meanwhile in quenched specimens formation of martensite was observed.

Mechanical Properties and Resistance Coefficient of Carbon Steel during Fire

AbstractRecently, serious fire accidents have occurred on bridges. For example, the 9‐Mile Overpass located near Detroit, MI, USA, experienced serious damage, where the steel‐concrete composite girder bridge fell down. To avoid future instances of such events, we need to understand the effect of the decrease in hardness of carbon steel during fire on structural characteristics, and to clarify the collapse mechanism of a bridge. Fifty years ago, the Japan Society of Steel Construction (JSSC) defined the mechanical properties of carbon steel up to 900 °C. However, recently, there have been bridge fire incidents where the heat has exceeded an estimated 1000 °C. Therefore, it is necessary to conduct the high temperature tensile test above 900 °C. In Japan, the design method has changed from the allowable design method to the limited design method, and a fire design method for the safety, serviceability and restorability of bridges has not been established. In near future, we seek to clarify the resistance coefficient for fire design. Herein, we carry out the high temperature tensile test to determine the relationship between strength and temperature, and propose a resistance coefficient for fire design based on these results. The 1 % yield strength of SM400 (minimum tensile stress: 400 N/mm2) decreased on average by 26 % at 500 °C, and on average by 94 % at 1100 °C. It was found that the elongation of carbon steel is greatest at 800 °C.

The influence of continuous casting technology on the cleanliness of carbon steel

The influence of the production method, i.e. casting technology on the cleanliness and thus the quality of carbon steels is best determined through the presence and type of non-metallic inclusions. A large number of inclusions, especially oxide and complex ones, can significantly affect the mechanical properties of carbon steels and limit their application for the production of finished products. This paper presents the influence of the presence, type and amount of non - metallic inclusions in B500B carbon steel according to ASTM / AISI produced by continuous casting technology without and with the application of stream protection.

Temperleme Isıl İşlem Sıcaklıklarının Karbonlu Çeliklerin Mekanik Özelliklerine Etkileri

Temperleme Isıl İşlem Sıcaklıklarının Karbonlu Çeliklerin Mekanik Özelliklerine Etkileri

WITHDRAWN: Strain rate effect on mechanical properties of 0.24% carbon steel using artificial neural network

The effect of strain rates on 0.24 percent C carbon steel under tensile loading has been discussed in this study. To perform the test by adjusting the strain rates, an electronic tensiometer was used. Before and after research, the microstructural orientations and stiffness around the necking area were defined by an optical microscope and a micro-hardness tester. At room temperature, the mechanical properties of carbon steel are investigated, such as ultimate tensile strength, yield strength and hardness. The lowest ultimate tensile strength (429.14 MPa) and lowest yield strength from the data were observed to have a strain rate of 1 mm/min (292.8 MPa). Strain intensity of 5.75 mm/min. The maximum ultimate strength (525.54 MPa) and highest yield strength are given (376.35 MPa). If the strain rate increases, the ultimate strength, and yield strength will rise and vice versa, the results showed. It can be observed that the hardness value improved to a reasonable level of 3.5 mm/min from 1.5 mm/min and decreased to 5.75 mm/min as the strain rate increased. The ANN model demonstrated an impressive contrast between the coefficient of correlation (R = 0.997) and the error in the mean square (MSE = 1.24 10-5) and the experimental findings. This analysis shows that the ANN model is capable of predicting the impact on Carbon steel’s mechanical properties of different rates for the strain.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Ultra-High-Carbon Steel

The effect of heat treatment parameters (the temperature of 850 – 930°C and the cooling rate of 1 – 20 K/min) on the microstructure and mechanical properties of carbon steel with 1.95 wt.% C is studied. The temperatures of the phase transformations in the steel are determined. X-ray diffractometry is performed. A heat treatment mode preventing the formation of ledeburite in the structure of the steel and promoting a uniform distribution of carbide particles in the matrix is suggested.

Post-fire mechanical properties of carbon steel and safety factors for the reinstatement of steel structures

This paper provides guidance on the post-fire material properties and associated safety factors for structural carbon steel which are required for the assessment and retrofitting of existing steel buildings which have suffered and survived a fire. Nowadays, there is a discrepancy between the methodology which is used in the design stage of a building (mostly based on the partial factor method) and the verification methods used after a fire. In the past decade, a number of researchers have published test data and there is more information available on the mechanical properties of steel following a fire. Nevertheless, a statistical evaluation of these results has yet to be conducted although design codes generally adopt a reliability-based approach for the analysis and assessment of buildings. To fill this gap of knowledge, the current article includes a statistical evaluation of the mechanical data from 718 tests collected from 19 peer-reviewed articles and doctoral theses. The study is done for hot-rolled steel, cold-formed steel as well as wrought or cast iron. By focusing on the effect of a fire on the mechanical properties after cooling, which is mostly related to how the coefficient of variation of their distribution increases, adjusted safety factors are proposed together with a reduced reliability index based on economic and social considerations. It is contended that by following this method, possible misunderstandings can be avoided and decisions on the salvage and rehabilitation of structures can be based on performance data and technical analysis, thus reducing the need for individual judgement.

Studying the Impact of Blast Treatment on the Structure and Mechanical Properties of Carbon Steel

The study has covered the effects of blast treatment on the microstructure parameters and mechanical performance of carbon steel. The calculation results of examining the structure and properties of carbon steel in its initial state and after explosive hardening in various sections of cylindrical carbon steel workpieces have been verified with the finite-element analysis using the ANSYS Workbench software environment. Blast treatment has been demonstrated to lead to a perceptible change in the structural state of carbon (cementite) in steel.

Mechanical properties of carbon steel by compound arc and vibration shock forging-rolling

Abstract To solve problems of coarse grains and low mechanical performance in low carbon steel parts fabricated by wire and arc additive manufacturing (WAAM), a novel compound arc and vibration shock forging-rolling (CAVSFR) method was proposed in this study. Carbon steel components were fabricated by the proposed method. And results showed that the total deformation of 28.3 % was obtained and the average grain size was reduced from 9.6 μm of WAAM to 6.4 μm. Grain refining was attributed to the static-force rolling, vibration-shock forging and micro self-forging of the molten pool. The large deformation in the medium-high-temperature zone, which provided more nucleation sites, accounted for grain refining in both static-force rolling and vibration-shock forging. Vibration shock greatly promoted dendrite fragmentation and more dendrite fragments were obtained as nuclei for new grains. Besides, the larger constitutional supercooling helped these nuclei survive and induced more nucleation, which could refine grains. These two factors were responsible for the grain refining in micro self-forging of the molten pool. What’s more, the refined grains enhanced the strength and plasticity of the material. The ultimate tensile strength (UTS), yield strength (YS) and elongation of the optimized component manufactured using the proposed method were increased to 555 MPa, 391 MPa and 38.9 %, which were enhanced by 14.2 %, 8.6 % and 1.8 % respectively and exceeded that of the wrought low alloy steel with the UTS of 550 MPa. Compared with other methods, small load and simple equipment could obtain components with the high performance through the proposed method.

Fe-Me-B Diffusion Layers for Surface Modification of Carbon Steels

Multicomponent boron-based diffusion layers are capable to provide a wider variety of surface improvements compared to pure boriding. In this research, we consider a way to increase mechanical properties of carbon steels by using two-component thermal-chemical treatment (TCT) such as boroaluminizing (B+Al), and boronickelizing (B+Ni). Diffusion treatment of steel surface was carried out by pack method in powder mixtures, and pastes, containing the above-mentioned elements and sodium fluoride as an activator. The exposure time was 3 hours, the treatment temperature was 950 °C. Pure boriding was conducted additionally to compare with two-component methods. The metallographic analysis revealed diffusion layers with a tooth-like structure after boriding and B+Ni. Typical composition of boride layer with iron boride FeB as an outer phase and Fe2B as an inner one was obtained after the first method. EDS analysis revealed a small amount of Ni (less than 1%) in boronickelized layer. Although XRD analysis revealed Ni2B, Fe3Ni3B besides iron borides and carboborides after B+Ni. Another structure was obtained after B+Al – namely a layered microstructure with outer softer iron aluminides and iron borides beneath. The thickest layer was obtained after boriding with the thickness of 140-160 μm, where higher value corresponds to low-carbon steel and vice versa. While for boroaluminizing the layer thickness was around 120-140 μm and for boronickelizing - 60-100 μm. Microhardness profiles differ significantly depending on the TCT method. For instance, initial high values followed by a drastic drop of hardness for boriding and boronickelizing. Wave type profiles characterize the microhardness distribution on boroaluminized samples. Wear tests indicated that samples with boride layer were the most wear resistant and the least resistant were the samples after B+Al. Fe-Me-B layers with the tooth-like structure are superior to the ones with the layered structure.

Crack Healing of High Temperature Hydrogen Attack Corrosion by Heat Treatment

Crack healing demonstrate as a ability of metal to repair physical damage by restructuring the carbon microstructure. High-Temperature Hydrogen Attack (HTHA) destruction happens when carbon steel equipment is exposed to hydrogen partial pressure at high temperatures. This will result in damage that severely degrades the mechanical properties of carbon steel. HTHA always happen at high-stress area in carbon steel such as a post-weld-heat-treated weldment and bending area in the form of the fissure exerted by methane gas inside the equipment. As more fissures are formed, it leads to form micro cracks and weaken the steel to cause a rupture. HTHA is difficult and challenging to inspect. In this research, the HTHA locations were identified by magnetic particle inspection (MPI) and heat treatment was performed by heating to annealing temperature and slowly cooled in the furnace. The early stages of attack with fissures or even small cracks detected are difficult to detect. When significant cracking detected, the particular point is already at higher possibilities of equipment to fail. Previous research has elucidated that there is a possibility of HTHA crack to reduce if undergoes for heat treatment. Heat treatment implies carbon diffuse into the matrix and hydrogen atoms escape. Therefore, diffusion plays an important part in the healing of HTHA crack as it plays a key role in the HTHA process. In this study, the specimen is 4-inch (10.16 cm) elbow pipe of the pipeline between distillation column and heat exchanger with a wall thickness of 1-inch (2.54 cm) had failed due to HTHA from pipelines which have been operating for 10 years. The failure occurs during operation on the pipelines between distillation column and heat exchanger. The crack length has reduced once the failed part was reheated to the annealing temperature of 850°C and slowly cooled in the furnace. The heat treatment by annealing also can be an alternative for altering the structure of the material in order to achieve desired properties and prepare the situation for further decision making by the process operation responsibilities. The conclusion for this research is to identify HTHA locations and restructure the microstructure of affected carbon steel by heat treatment. Results revealed that cracks length had reduced 3 to 10% by heating the failed pipe to annealing temperature and then slowly cooled for microstructure recover. However, the hardness had reduced and further research should be extended to overcome this problem.