M2 Steel Research Articles

Electrodeposition of Al coating onto a 300M steel from AlCl3/acetamide deep eutectic solvents for corrosion protection

Aluminum coating was expected to be used for corrosion protection of 300M steel. Al coating was prepared using the galvanostatic electrodeposition from AlCl3/acetamide (1.3:1) system for the corrosion protection of 300M steel. This process was conducted at varying current density (2–8 mA·cm−2) and electrodeposition time (1 and 2 h). The chronopotentiometry revealed that the size of Al nucleus was proportional to the inverse of overpotential. Thus, the morphology of Al coating was characterized by scanning electron microscope and optical surface profiler. The results indicated a decrease in Al grain sizes and the roughness fluctuation with increasing current density. Moreover, the corrosion resistance of Al coatings was evaluated in a 3.5 wt% NaCl solution using the potentiodynamic polarization and electrochemical impedance spectroscopy test. It was illustrated that corrosion current density decreased by 57.8 % at 6 mA·cm−2 with the electrodeposition time increasing from 1 to 2 h, while the value decreased by 75.9 % with the current density raising from 5 to 6 mA·cm−2 for 2 h. Al coating electrodeposited at 6 mA cm−2 for 2 h represented the highest corrosion resistance with the charge transfer resistance of 5695 Ω·cm2, while the value of 300M steel was 914 Ω·cm2. Finally, X-ray diffraction pattern suggested that corroded coatings compositions included Al2O3, AlO(OH) and AlCl3·6H2O. The study was considered to provide a promising method using AlCl3/acetamide to electrodeposit Al coatings for protecting 300M steel from corrosion.

Behavior of M2 steel with CrN/TiN thin films by cathodic arc PVD method

The objective of this project is to obtain results on the films generated on M2 highspeed steel substrates, used in cutting applications and wear resistance. These samples were coated with CrN as the base layer and TiN as the film, using the PVD cathodic arc method. The project was carried out in collaboration with SADOSA S.A. de C.V., a company specialized in industrial coatings for high-speed cutting tools.The methodology included microstructural characterization through scanning electron microscopy (SEM) and composition analysis (SEM-EDS), along with topographical analysis using optical profilometry. The film thickness was determined using the calotest method, and tribological analysis was conducted with the pin-on-disk technique, obtaining wear tracks, volume loss, and specific wear rate according to ASTM G99 standards. The adhesion of the films was also evaluated using VDI 3198 standards to assess the adhesion quality of the samples. Finally, the data were collected for the analysis of the obtained results.

Simulating the effect of elevated temperature on the compressive strength of steel fiber reinforced concrete (SFRC) using ANSYS workbench

The behavior of concrete structures at elevated temperatures is of significant importance in predicting the safety of structures in response to certain accidents or particular service conditions. The behavior of M50 Steel Fiber Reinforced Concrete (SFRC) at 28-days strength subjected to elevated temperatures was simulated using ANSYS 2020 R2 Workbench, and results validated with experimental results from a referenced Journal. M50 concrete at 28-days was modelled along with steel fibers from 0 to 4% by weight of cement. Models were made and subjected at room temperature, 100, 200, 300, 400 and 500°C from ANSYS Workbench Static Structural module. The concrete matrix was modelled as solid body, while the steel fiber reinforcement as line bodies, the new ANSYS reinforcement workflow that allows for simulating proper bond between concrete and rebar was utilized. Compressive strength results were determined as Average Von-misses stress and results validates that obtained from the referenced literature. This work has developed results with variations compared to the experimental work largely below 5% and has given important reasons to assert that results obtained from experimental works can be obtained with FE simulations and that laboratory works can be simulated with FE programs to cut down on cost and time associated with the former. In other words ANSYS Workbench program is a good validatory tool for similar experimental research.

Friction and Wear of DLC Coating Deposited on M2 Steel via µW-PECVD Against 100Cr6 Steel with Different Normal Loads and Sliding Speeds Under Dry and Lubrication Conditions

Friction and Wear of DLC Coating Deposited on M2 Steel via µW-PECVD Against 100Cr6 Steel with Different Normal Loads and Sliding Speeds Under Dry and Lubrication Conditions

Influence of Ultrasonic Surface Rolling on the Tensile and Fatigue Properties of Laser-Cladding-Repaired 300M Steel Components

Abstract Herein, to address the issue of decreased tensile and fatigue performances observed in 300M steel scratched parts after laser-cladding repairing, an ultrasonic surface rolling process (USRP) was employed to enhance the strength of the laser-cladding-repaired (LCR) samples. Results indicated that USRP led to the formation of a strengthening layer on the surface of the samples. In the parent material area, the thickness of the strengthening layer was 180 μm, while in the cladding area, it was 35 μm. The superficial microhardness increased by 11.6% in the parent material area and by 5.0% in the cladding area. Furthermore, the surface residual stress transitioned from tensile to compressive stress, reaching a maximum of 1169.9 MPa. Improvements were observed in the tensile performance, as evidenced by a reduction in the length of the tearing ridge in the fracture morphology. In addition, the fatigue life considerably increased, initially increasing and then decreasing as the number of rolling passes increased. After four cycles of USRP, the fatigue life of the samples was the highest, which was about 18.4 times that of an unprocessed sample. The origin location of cracks shifted from the surface to the interior of the samples. This shift was accompanied by a decrease in the instantaneous fracture area and the emergence of additional secondary cracks. These experimental results demonstrate that USRP is an effective technique for improving the tensile and fatigue performances of LCR 300M steel samples.

Effect of alternative magnetic fields with different intensities on microstructure and mechanical properties of M50 steel during vacuum arc remelting

Effect of alternative magnetic fields with different intensities on microstructure and mechanical properties of M50 steel during vacuum arc remelting

Microstructure and properties of TiC ceramic powder on a cobalt-based alloy obtained via electromagnetic-assisted laser metal deposition

The crack sensitivity of laser metal ceramic deposition is an important factor restricting its development. In this paper, a TiC-reinforced cobalt-based alloy was deposited on 300M steel using electromagnetic-assisted laser metal deposition technology. The electromagnetic composite effect on the microstructure, mechanical properties, magnetic properties, wear resistance and crack sensitivity of the laser metal deposition layer was discussed. Under the action of an electromagnetic field, the size of the TiC decreased by 54.6% compared with that of the deposited layer without an electromagnetic field. The effect of the electromagnetic composite field can reach the bottom of the molten pool, thus refining the grain size at the bottom of the coating. This resulted in a 22% increase in the hardness of the deposition layer. The electromagnetic field effect reduces the elastic modulus of the deposition layer, thus improving the mechanical properties of the coatings. In addition, compared with that of the deposition layer without an external field, the wear of the deposition layer with an electromagnetic force is obviously reduced. With increasing electromagnetic parameters, the wear resistance of the deposit increased gradually, and the thermal expansion coefficient decreased significantly, which played an important role in improving the crack resistance and comprehensive properties of the deposition layer under extreme working conditions.

Effect of electrical current on sliding friction and wear mechanisms in a-C and ta-C amorphous Carbon coatings

This study investigated the sliding wear behaviour of amorphous carbon (a-C) and tetrahedral amorphous carbon (ta-C) coatings, two forms of diamond-like carbon (DLC) coatings, against SAE 52100 steel using a modified ball-on-disk tribometer with applied electrical currents ranging from 100 mA to 1800 mA. It focused on the variations in sliding friction and wear characteristics of these coatings as electrical currents increased under constant load and speed conditions. The a-C coatings exhibited lower coefficient of friction (COF) values and reduced volumetric wear losses up to 1500 mA, while ta-C coatings studied displayed higher wear, similar to uncoated M2 steel, at 300 mA with degradation occurring at low currents, resulting in failure due to severe oxidational wear. The a-C coatings showed no significant electrical damage at these currents. Raman spectroscopy revealed structural changes on the wear tracks of sp2-rich a-C coatings, specifically the formation of graphene layers. In comparison, the wear tracks of sp3-rich ta-C coatings did not display such transformation under the conditions studied. The graphene coverage on the surfaces of the a-C coatings increased with the increase in the current as revealed by the Raman intensity maps of 2D peaks and this increase was accompanied by a higher defect density in the graphene. The low COF of graphene-covered a-C surfaces was consistent with the proposed mechanisms of moisture adsorption. However, at currents exceeding 900 mA, surface temperatures of a-C coatings exceeded 100 °C, impairing graphene's ability to maintain low friction, resulting in an increased COF.

Effect of the Absorption Layer on the Microstructure and Mechanical Properties of M50 Steel by Laser Shock Peening

Effect of the Absorption Layer on the Microstructure and Mechanical Properties of M50 Steel by Laser Shock Peening

Study on corrosion behavior and first-principle analysis of M50 steel in lubricating oil contaminated by salt water

The corrosive wear of M50 steel in lubricating oil contaminated with saline is a form of wear that often occurs within the main shaft bearings of aviation engines carried by aircraft working at sea. In the present paper, the corrosion behavior of M50 steel in lubricating oil contaminated with saline was studied. The open-circuit potential, polarization curve and impedance spectrum were analyzed by rotating electrochemical corrosion wear test. A three-layer interface microscopic molecular model was established with Materials Studio to simulate the dynamic corrosion evolution process of M50 steel self-matching pairs and the adsorption energy was calculated. The results show that the corrosion type is pitting corrosion. With the increase of saline concentration, the corrosion area becomes wider and shallower, and the size of the pitting core gradually decreases. The weight loss of M50 steel increases over time, but the trend slows down, which is also shown in the MS simulation results. Electrochemical tests show that the tribocorrosion of M50 steel is related to load, speed. As the load increases, the corrosion rate decreases. And, as the speed increases, the corrosion rate increases. This has practical significance for extending the understanding of tribocorrosion of M50 steel in marine atmospheric environments.

Influence of shot-peening on the self-heating behavior and fatigue properties of 300M steel

Shot peening is an established cold working process used to introduce residual compressive stresses on a surface and is extensively studied using conventional fatigue tests. However, it has not been widely studied using the self-heating method. Specifically, the heterogeneity of the dissipation field has not been estimated, with only an average approach being used. Previous investigations in the case of 300M steel demonstrated that the effect of shot peening on the high cycle fatigue properties can be either beneficial or detrimental. This study proposes to apply the self-heating method on polished 300M and to investigate the effect of mean stress and shot peening on the dissipation behavior. A modified self-heating model is proposed and calibrated for 300M steel. Combined with residual stress profiles, a method to compute and determine the shot peening effect on self-heating behavior through single point surface measurements is proposed. Application on 300M steel shows excellent results, the over-dissipation being mainly due to the sub-surface compressive residual stresses. The self-heating method has proven useful to quickly estimate fatigue properties of polished 300M steel. Based on the understanding of the self-heating curve of shot peened 300M steel, a quantification of shot-peening effect on fatigue limit is discussed.

Rolling contact fatigue property of gradient rare earth addition M50 bearing steel with surface nano-grains and its inhibited martensite decay

A gradient nanostructured surface layer of ∼600 μm in thickness was prepared on M50 steel with rare earth additions by a surface mechanical rolling treatment. The initial microstructure was refined into nanosized grains (∼29 nm in diameter) in the top surface layer, causing a significant increase of surface hardness. Meanwhile, the grain size increases, and the microhardness decreases gradually to the matrix values with increasing depth. Rolling contact fatigue tests showed that the fatigue lives are significantly increased by the gradient nanostructured surface layer. Analysis of failure mechanism revealed that both softening in the near surface layer and hardening in the subsurface occur under rolling contact testing. And surface spalling is the predominant failure mode, of which the cracks initiate from primary carbides in the top surface layer owing to surface softening. In gradient nanostructured samples, the nano-grains inhibit carbon migration by impeding dislocation movement in the near surface layer, so that martensite decay is suppressed. Consequently, the crack initiation is inhibited, and the fatigue property is enhanced.

Electric current-induced directional slip of dislocation and grain boundary ordering

The evolution of lattice dislocations in metals can be induced by electric current. However, the effect of electric current on the interaction between lattice dislocations and grain boundaries (GBs) remains unclear. Herein, we investigate the evolution of lattice dislocations and grain boundary dislocations (GBDs) induced by electric current in M50 steel via in-situ TEM characterization, density functional theory (DFT) calculations, and molecular dynamics (MD) simulations. Our findings reveal that electric current induces the directional slip of lattice dislocations towards GBs, while the reduction of GB contrast is attributed to the decomposition and reorganization of GBDs. DFT calculations demonstrate that electric current enhances the force on atoms in defect regions. These in-situ TEM observations are well reproduced by MD simulations incorporating electric current, which include a virtual temperature rise at defect regions to reflect the electric current force on defect atoms. Based on these observations, we propose a novel GB accommodation model under electric current. These results provide valuable insights into the mechanisms by which electric current tailors lattice dislocation behavior and enhances GBDs ordering in metallic materials.

Flexural Behaviour of Concrete Beams Reinforced With Major Steel Bars under Normal and Corrosive Operational Conditions

Quality assurance of construction materials is very fundamental for structural safety, reliability, serviceability, and durability of constructed civil infrastructure. Inflow of defective or substandard building and construction materials into the industry, particularly reinforcing steel bars, is responsible for many structurally deficient constructed facilities which often lead to failure or ultimate collapse of reinforced concrete (RC) structures. Characterization of steel rebars from two major manufacturers into Botswana construction industry, designated herein as M1 and M2, were conducted as a basis for the evaluation of the quality assurance and control of the products. The flexural behaviour of their respective RC beams, designated herein as B-M1 and B-M2, of dimension 150 × 200 × 3000 mm and subject to four-point loading tests were determined under normal and artificially induced corrosion conditions to assess the influence of steel rebars M1 and M2 on the stiffness and load-carrying capacity. The average yield strengths of steel reinforcing bars were 427 N/mm2 for M1 and 459 N/mm2 for M2. The moduli of elasticity for M1 and M2 were 203 GPa and 205 GPa, respectively. The percentage elongation was found to be 7.93% for M1 and 7.24% for M2. The flexural strength of beams reinforced with M1 was 7% and 16.5% lower than RC beam with M2 under normal and accelerated corrosion of 5% of NaCl solution for 60 hours condition, respectively. The flexural behaviour of RC beams reinforced with B-M1 had a lower flexural strength under both normal and corrosive environmental conditions as compared to B-M2. The flexural strength of B-M1 had reduced from 48.5 N/mm2 to 41.0 N/mm2, while B-M2 reduced from 52.2 N/mm2 to 49.2 N/mm2. This represented loss of load-carrying capacity of 15.4% and 5.8% for B-M1 and B-M2 respectively due to exposure to corrosive environment. The findings revealed disparity in bending capacity due to the low interfacial bonding due to reduced relative rib areas. A more intensive quality control of imported steel should be ensured at the ports of entry by relevant regulatory agencies.

Effect of Martensite–Bainite Duplex Microstructure on Carbide Precipitation and Mechanical Properties of M50 Steel

By means of microstructure observation, phase analysis, and mechanical‐property tests, the effect of martensite–bainite (M–B) duplex microstructure on carbide precipitation and mechanical properties of M50 steel is studied. In that results, it is shown that the distribution of secondary carbides in specimens with M–B duplex microstructure is more uniform and finer, and the stability of retained austenite (RA) in the steel is also improved, so that the content of RA in specimens with M–B duplex microstructure is 2.34%, which is higher than the 0.94% of the specimens with full martensite microstructure. The M–B duplex microstructure leads to the reduction of tempering hardness of M50 steel to 60.9 unit of Rockwell hardness (HRC), compared to the 61.6 HRC of the specimens with full martensite microstructure, but the wear resistance is slightly enhanced. Moreover, the M–B duplex microstructure effectively improves the impact toughness and fatigue properties by refining the microstructure and carbides in the steel, and the increase amplitude is 47.4% and 41.0%, respectively.

Residual fatigue life prediction based on a novel improved Manson-Halford model considering loading interaction effect

The classical nonlinear fatigue cumulative damage model Manson-Halford is widely used in fatigue life analysis and prediction, but this model lacks consideration for the effects of load interaction. At present, some studies have proposed new correction models to overcome the shortcomings of classical models. However, the problem with these models is that the parameters are difficult to determine, resulting in a cumbersome application process or the correction process is based only on a single parameter. Insufficient correction leads to large fluctuations in life prediction errors. To overcome the above problems, this article proposes a new correction method and establishes a new improved model. Unlike existing models, the newly improved model is based solely on S-N curve parameters and does not require additional material parameters. It fully considers the relationship between adjacent loads and the difference in fatigue life under different stress states, and dynamically modifies the classical model based on larger influence weights. By conducting multi-level fatigue tests on 300M steel, a new improved model was used to accurately predict its remaining fatigue life. Compared with the classical model, the prediction error was reduced by 11.75 %. Utilized fatigue test data from various other materials to predict the fatigue life of the improved model under different levels of stress loading. The results indicate that in the vast majority of cases, the improved model has the highest prediction accuracy among all compared models, with a minimum relative prediction error of only 3.79 % and small fluctuations in prediction error. Compared with the classical model, the maximum reduction in relative prediction error after model improvement reached 28.73 %, indicating the effectiveness and accuracy of the new improved model.

Effect of Compound Treatment of Laser Shock Peening and Nitriding on Wear Resistance of M50 Steel

Effect of Compound Treatment of Laser Shock Peening and Nitriding on Wear Resistance of M50 Steel

Contact fatigue of thin hard diamond-like carbon films on M50 steels under cyclic spherical micro-indentation

Contact fatigue behaviors of thin hard diamond-like carbon (DLC) films on M50 steels during cyclic spherical micro-indentations were investigated. The stress-strain evolution of the entire system was analyzed by finite element methods. The film fracture mechanisms and interfacial bearing responses under monotonic and repeated contacts were comprehensively explored. Concentrated tensile and shear stresses were found to, respectively, govern the initiation and propagation of the surface ring cracks. Elevated tensile stresses at the initiation and epilogue of each indentation cycle enhanced bottom radial cracking. At the interfaces, the maximum tensile (σnmax) and shear (σtmax) stresses occurred at the end of unloading and loading processes, respectively. With increasing maximum indentation forces, σnmax initially increased and then gradually decreased, while σtmax increased monotonically.

Surface melt nitriding and strengthening mechanism of plasma torched M50 bearing steel

This paper presents a new plasma torch nitriding technology for the first time to realize the surface nitriding of bearing steel for strengthening. By adjusting the plasma torch current parameters in the range of 120–160 A, M50 bearing steel was carried out at a nitriding speed of 2 s/cm2. After nitriding, the nitrogen content was increased from 0.00732 wt% in the original M50 steel up to 0.416 wt%, and the thickness of the nitrided layer was up to 2.51 mm. FeN0.076, Fe2N and Fe3N phases were formed in the steel, which was beneficial to increase the hardness and strength of bearing steel. The Vickers hardness of the original M50 bearing steel was 241 HV0.2. However, the highest surface hardness of specimen after nitriding was increased up to 778 HV0.2, which was attributed to the effect of sub-surface hardness strengthening within 2 mm from the depth of nitride surface. The average wear coefficient and the volumetric wear rate of the specimen after nitriding were decreased by about 32 % and 70 %, respectively. TEM observation showed that after nitriding, the structure of nitrided layer was martensite. The precipitates in the steel changed from large-sized, irregular and aggregated carbides (M23C6, M4C3 and M2C) to small-sized, spherical and uniformly distributed carbon‑nitrogen composite precipitates (M23(C, N)6, M7(C, N)3) in the steel sub-surface, but no obvious precipitates were formed on the surface of nitrided specimens. At depths of 1 mm and 2 mm, the size of the precipitates was reduced by about 68 % and 41 %, respectively, and the area of the precipitates was reduced from 18.4 % to 2.3 % and 3.7 %, respectively, compared to the original M50 bearing steel. It was concluded that the nitrided layer were strengthened synergistically with nitrogen solid solution, nitrogen-containing precipitates and martensite.

Effect of Temperature on the Structure and Tribological Properties of Ti, TiN and Ti/TiN Coatings Deposited by Cathodic Arc PVD

Monolayers of Ti and TiN coatings, as well as a Ti/TiN bilayer coating, were deposited on AISI M2 steel substrates using the PVD cathodic arc technique. The coatings had a thickness close to 5 μm and an average roughness between 98.6 and 110.1 μm due to the presence of microdroplets on the surface. The crystalline structure of the materials was analyzed using Grazing Incidence X-ray Diffraction (GIXRD) with an increase in temperature to study the dynamics of oxide formation. A phase composition study was conducted using the Rietveld refinement method. At the temperatures where critical growth of titanium oxides, both anatase and rutile, was observed, pin-on-disk tests were performed to study the tribological properties of the materials at high temperatures. It was determined that the oxidation temperature of Ti is around 450 °C, promoting the formation of a combination of anatase and rutile. However, the formation of rutile inhibits the formation of anatase, which is stable above 600 °C. In contrast, TiN showed an oxidation temperature of 550 °C, with an exclusive growth of the rutile phase. The Ti/TiN bilayer exhibited mixed behavior, with the initial growth of anatase promoted by Ti, followed by the formation of rutile. Oxidation and tribo-oxidation dominated the wear behavior of the surfaces, showing a transition from mechanisms related to abrasion at low and medium temperatures to a combination of abrasion and adhesion mechanisms at high temperatures (800 °C).