C45 Steel Research Articles

Influence of interlayer time on the microstructural state of CoCrMo coatings applied by selective laser melting on an iron-based substrate for different numbers of layers

The Selective Laser Melting process was used to perform cobalt-based alloy coatings on a C35 steel substrate. The relationships between interlayer times, iron dilution, crystalline structures, and micro-hardness were studied for different numbers of layers with an initial lased powder layer of 50 µm thickness. Reducing the interlayer time increased the temperature reached in the melting bed and promoted matter transport from the substrate. The coating thickness consisted of a Co-Cr-Fe mixture, divided into two zones: a transition zone near the interface and a stabilized zone towards the substrate. The real coating thickness was found to be always greater when the interlayer time was reduced. For an interlayer time equal to 11 s (series 2), the iron dilution was always higher than for an interlayer time ranging between 42 s and 16 s (series 1), leading to a higher coating thickness. The microstructural state was also dependent on the interval time between successive layers. The coating microstructure was always cellular because of the high cooling rate. XRD analysis of the surface showed that this microstructure is essentially composed of two non-equilibrium phases: FCC and α’ BCC. The high hardness is due to the high content of iron which induces a martensite phase (series 2). Starting from 5 layers for series 1 and from 6 layers for series 2, the α’ BCC phase disappeared if the iron content on the coating surface was reduced by more than 45% content in weight. The mean coating hardness decreased with an increasing number of layers because of the decrease in the iron content. Finally, the micro-hardness of the FCC phase, for its part, was found to be dependent on the iron content in solution in the Co matrix.

Heat Treatment Process Study and ANN-GA Based Multi-Response Optimization of C45 Steel Mechanical Properties

Heat Treatment Process Study and ANN-GA Based Multi-Response Optimization of C45 Steel Mechanical Properties

Measurement of the Machined Surface Diameter by a Laser Triangulation Sensor and Optimalization of Turning Conditions Based on the Diameter Deviation and Tool Wear by GRA and ANOVA

One of the most important operations in the technological production process is the inspection of the manufactured product. The gradual wear of the tool affects the achievement of the required quality of the functional surfaces. In this research, we present the results of measuring the diameter deviation with a new generation laser triangulation sensor (LTS). At the same time, we have performed parametric optimization of several multi-responses, such as insert wear on the VBB flank side of cutting edge and diameter deviation Δd for a C45 steel sample during dry turning and using a sintered carbide insert, using the method of grey relational analysis (GRA) in combination with the Taguchi L16 orthogonal array. The optimal setting of input factors for multi-response parameters is ap 4-f 4-vc 1 i.e., depth of cut 0.5 mm, feed 0.4 mm per revolution, and a cutting speed of 70 m/min. At the same time, we present an evaluation of the significance of input factors using the method ANOVA.

Machining Character Analysis of Coated and Uncoated End Mill on Heat Treated C45 Steel

Abstract: Machining operations are used to produce shapes or surface characteristics for a product. Some common conventional machining operations are turning, boring, drilling, reaming, milling, and tapping. Conditions for machining operations were chosen based on geometry and surface finish requirements rather than profit when costs were comparatively low on labor, resource, machines, and tools. However, nowadays, many researchers proposed optimizing machining parameters to maximize profit when using expensive modern machine tools. The purpose of machining operations is to make specific shapes or surface characteristics for a product. Conditions for machining operations were traditionally selected based on geometry and surface finish requirements. This study was investigated the parameter optimization of end milling operation various parameter and coated tools and ordinary tool with heat treated C45 steel with single objective function criteria based on the Taguchi orthogonal array with the Taguchi design. Comparison of coated and uncoated end mill process of heat-treated C-45 steel fine Ra is obtained with coated tool. Kerf width almost equal of both tools it did not show any major difference Optimum level and ANOVA were calculated for both tools. Keywords: Ra, PVD coated, Heat treatment, End mill

Validation of a new system for measuring material constants representing damage limits

This paper describes a test for the determination of damage function limits. The proposed test consists of skew rolling of conical specimens. The test is carried out under real conditions to determine the crack initiation point, and then it is modelled numerically to determine the limit values of the damage function at the determined crack initiation point. This paper presents a methodology for the determination of limit values of the damage function on the example of C45 steel at three different temperatures, i.e. 950 °C, 1050 °C and 1150 °C. The research was carried out using the Oyane criterion as an example. The limit value of the damage function at 1000 °C was determined by regression using the calculated damage function values. The value of the damage function was adapted to a numerical model of a skew-rolling process of a bar with the deletion of elements, which took place when the limit value of the damage function determined in the test was exceeded. The numerically simulated skew rolling case was also realised in real conditions. Based on the results obtained from the skew rolling of bars, a quantitative and qualitative validation of the new damage function limit test was carried out.

On the correlation of temperature harmonic content with energy dissipation in C45 steel samples under fatigue loading

Fatigue damage onset involves a transformation of mechanical energy. This is in part spent into work of plastic deformation and fracture and in part transformed into heat. Therefore, different thermomechanical heat sources are activated during a fatigue loading cycle, resulting in a temperature modulation that can be characterized by its frequency content. Several studies have monitored the temperature on samples undergoing high-cycle fatigue, measuring specific thermomechanical metrics which could serve as indicators of damage evolution. The present work evaluates the harmonic content of temperature, to investigate its correlation with the material dissipation. The harmonic terms investigated are the amplitude and phase of temperature at the loading frequency (First Harmonic) and at twice the loading frequency (Second Harmonic). The paper reviews the mechanisms linking the evolution of heat dissipation to changes in these four parameters. The theoretical analysis is supported by an experimental campaign carried out on C45 steel tensile specimen subject to R=−1 and R=0.1 loading ratios. The harmonic metrics are evaluated analyzing both their spatially averaged value and their spatial dispersion, to check for the formation of localized heat dissipation zones in early fatigue life. The study shows that the phase of the Second Harmonic signal has a peculiar bimodal distribution that can be correlated to either a thermoelastic or dissipative prevailing effect. This behavior evolves towards a unimodal dissipative behavior when the load amplitude is increased, thus proposing the Second Harmonic phase parameter as an effective indicator for monitoring internal intrinsic dissipation in the material.

Improvements of surface tribological properties by magnetic assisted ball burnishing

The effect of the magnetic assisted ball burnishing on a general, C45 steel was investigated considering tribological aspects. In engineering practice, the tribological properties of machined surfaces are characterized by amplitude roughness parameters from roughness profiles, as Rpk, Rk, Rvk, Rsk and Rku. Information about the sliding properties can be described by these parameters together with the oil retention capacity of the surface. Despite the conventional burnishing processes used as a post-machining operation, the authors applied a newly designed magnetic assisted ball burnishing method and tool, which can also burnish flat or harmonically changing surfaces and is able to round the edge of the workpiece in one pass as well, immediately after milling. To increase efficiency of the applied burnishing process, different types of burnishing strategies were applied and compared. The results of the investigations showed that the magnetic assisted ball burnishing decreases the frictional resistance, and at the same time it creates advantageous oil pockets on the machined surface.

Synthesis, structural and the corrosion inhibition of phosphate-based xPbO–yB2O3–zP2O5 glass for C35 steel in acidic media

Synthesis, structural and the corrosion inhibition of phosphate-based xPbO–yB2O3–zP2O5 glass for C35 steel in acidic media

Structural Materials Durability Statistical Assessment Taking into Account Threshold Sensitivity

This work presents an experimental—analytical study of the possibility of applying the method of the greatest probability to evaluate the sensitive thresholds of the bottom (N0) and top (Nk) of the statistical distribution of the mechanical structural characteristics. For the structural materials alloyed steel 15Cr2MoVA, steel C45 and aluminium alloy D16T1, the statistical distribution of proportional limit, yield strength, ultimate tensile strength, reduction in area, cyclic stress was estimated, as well as the following statistical parameters: mathematical mean, average square deviation, dispersion, asymmetry, variation coefficient, and excess. Purpose: to determine whether the limits of the sensitivity of the statistical distribution of the mechanical characteristics have been computed using the maximum likelihood method. Value: there is a certain upward and downward flattening of the probability curves in the statistical distribution curves of the fatigue test results. This implies that the chosen law of the distribution of random variables has an effect on the appearance of errors. These errors are unacceptable given the importance of accurately determining the reliability and durability of transport means, shipbuilding, machinery, and other important structures. Our results could potentially explain why sensitive limits cannot be applied to the statistical distribution of the mechanical characteristics of structural materials.

Characterization of Fe–Al intermetallic phases formed during hot-dip Al coating on carbon steel C45

Characterization of Fe–Al intermetallic phases formed during hot-dip Al coating on carbon steel C45

The Effect of Coatings on Cutting Force in Turning of C45 Steel.

This article focuses on the development of a mathematical model of a cutting force that is applicable for coated and uncoated cutting tool inserts and aims to enable more accurate calculation of the cutting force. Two common PVD coatings, AlTiN and TiAlCrN, were used. Firstly, a mathematical model of the cutting force based on the specific cutting force and cutting area is proposed. This mathematical model considers the cutting speed and coating correction factor as well as the real cutting edge geometry, i.e., it includes both the straight and rounded parts of the cutting edge. For this proposed model, material constants for C45 steel, which was machined with uncoated inserts, were obtained. Before determining an equation for a coating correction factor and implementing it into the model, experimental cutting force data for coated and uncoated inserts were compared using a paired t-test. The result was that the difference between them was statistically significant. Their percentage difference was found to be up to 4%. The correction factor equation that was obtained and implemented into the mathematical model was applied to compare the calculated and experimental data of the coated inserts, also using a paired t-test. The result was that the difference between them was insignificant. Moreover, their percentage difference was found to be up to 0.6%.

The Influence of Cutting Parameters on Plastic Deformation and Chip Compression during the Turning of C45 Medium Carbon Steel and 62SiMnCr4 Tool Steel.

The paper deals with the issue of cutting zone and chip compression. The aim was to analyse the microstructure transverse section of the cutting zone on a metallographic cut, due to determined values of chip compression and plastic deformation, which affect the cutting process efficiency. The tested cutting tool material was coated with cemented carbide. The selected workpiece materials were C45 medium carbon steel of ISO grade and 62SiMnCr4 tool steel of ISO (W.Nr. 1.2101) grade. In the experiments, a DMG CTX alpha 500 turning centre was used. The cutting speed and feed were varied, and the depth of the cut was kept constant during the turning. The plastic deformation and chip compression determine the efficiency of the cutting process. The higher compression requires more work to perform the process and, therefore, it requires more energy for doing so. With the increase of the cutting speed, the deformation for C45 steel is decreased. The rapid deformation reduction was observed when the cutting speed was increased from 145 m/min to 180 m/min. Generally, deformation is decreasing with the increase of the feed. Only at a cutting speed of 145 m/min was the deformation elevation observed, when the feed was increased from 0.4 mm to 0.6 mm. During the turning of the 62SiMnCr4 tool steel we observed an error value at a cutting speed of 145 m/min and a feed of 0.4 mm was the middle cutting parameter. However, feed dependence was clear: With an increase of the feed, the plastic deformation was decreasing. This decreasing was more rapid with the increasing of the cutting speed. Besides plastic deformation, there was analysed chip compression as well. With the increasing of the cutting speed, there was a decrease of the chip compression. Due to a lack of information in the area of the chip compression and the plastic deformation in the cutting process, we decided to investigate the cutting zone for the turning of tool steels 62SiMnCr4, which was compared with the reference steel C45. The results could be applied to increase the efficiency of the process and improvement of the surface integrity.

Method for an Effective Selection of Tools and Cutting Conditions during Precise Turning of Non-Alloy Quality Steel C45.

The paper presents a constructing methodology for a modern approach to tools selection and solving the problem of assigning optimal cutting parameters for specific production conditions. The mathematical formulation determining the extreme values of the technological process optimality criteria is obtained. A system of technical and economic quality indicators for cutting tools is proposed. This system allows principles’ implementation of decentralization and interoperability “Industry 4.0” via finite element modeling of the cutting process based on solving the problem of orthogonal free cutting modeling. The proposed methodology further usage is possible by creating a standardized database on the parameters of the tool: the adhesive component of the friction cutting coefficient for processing of a specific pair of cutting and tool materials (or tool coating material) and the impacts of the cutting-edge radius on cutting efficiency of a particular material.

The effect of temperature on water desorption and oxide formation in MoS2 coatings and its impact on tribological properties

Molybdenum disulfide (MoS2) is used extensively in aerospace applications, where liquid lubricants are not suitable. MoS2 has excellent tribological properties in vacuum, however, further research is required to fully understand the mechanisms taking place when exposed to varying temperatures in ambient atmosphere due to storage and on-ground testing. MoS2 coatings were deposited on AISI 440C steel substrates, friction and wear tests were conducted at increasing temperatures, up to 75 °C, determining the effect of temperature on wear mechanisms in air. It was found that the detected surface oxides do not impact tribological properties in MoS2 at temperatures around 75 °C. The water molecules at room temperature hinder the alignment of MoS2 layers leaving some active edge sites exposed to contacting surfaces, leading to high friction and wear. Desorption of water molecules promote parallel alignment of layers, reducing shear strength, friction and wear.

Evaluating the Corrosion Behaviour of Borided Carbon Steel C35

In this work, an evaluation of corrosion resistance of boride layers formed on carbon steel C35 in different solutions of H2SO4, HCl, HNO3, NaCl and NaOH was carried out. Boriding treatment was applied on C35 carbon steel using Ekabor powder at 950 °C for 4 h. The corrosion behaviour was analyzed by the weight loss method after total immersion tests in different solutions at variable times from 24 hours to 6 months. The corrosion rate has been determined by electrochemical method using the polarization curves. Results obtained show that boriding treatment improved significantly the corrosion resistance of C35 steel in some acidic environments. The corrosion resistance of boride C35 steel is higher compared with that of untreated C35 steel, and the corrosion potentials Ecor of boride C35 steel are more electropositive than those of untreated C35 steel in some solutions.

A modified Johnson-Cook constitutive model for improved thermal softening prediction of machining simulations in C45 steel

A new modified Johnson-Cook model is developed to capture the non-linear thermal softening behaviour below the austenite transformation temperature (723°C) in C45 ferritic-pearlitic steel, which is not captured by the original Johnson-Cook (JC) model. The physical mechanisms responsible for this behaviour are also studied. The model is developed by experimental quasi-static and high strain rate axisymmetric compression testing from 20°C to 720°C and implemented into 3D finite element drilling simulations. The improvement over the original JC model is demonstrated by comparison to experimentally measured torque and thrust force.

Machinability of maraging steel multilayered claddings obtained via laser direct energy deposition in micromilling operations

Laser direct energy deposition is commonly used to improve the surface properties of poorly resistant materials, repair worn portions, or change the shape of a component. In this paper, C45 steel substrates were laser deposited with multiple layers of grade 300 maraging steel. Micromilling operations were then carried out on the laser depositions both in as-built and heat-treated conditions to improve the surface integrity. The cutting forces were measured at varying cutting directions. An in-depth characterization of the surface integrity induced by micromilling was conducted, considering microstructural features, microhardness, surface topography, and surface defects. The results proved that the laser deposition-induced anisotropy had a remarkable influence on the laser deposited material machinability and must be taken into account.

Analysis of the contact mechanics in machining using a novel high-speed tribometer

A new high-speed pin-on-bar type tribometer has been developed to study the variation of the friction coefficient with respect to the local thermomechanical contact conditions between the tool and the workpiece when drilling C45 steel. The forces and temperatures are measured over a range of pin indent depths and sliding velocities in open and closed loop tribo-systems. The tribometer’s ability to recreate the thermomechanical contact conditions in drilling is demonstrated and the induced surface modification in the workpiece by the tribology testing is studied.

Effect of elliptical defect orientation on the durability of specimens subjected to cyclic bending

This work presents the effect of elliptical defects orientation on the durability of specimens made of C45 steel. Three kinds of specimens with elliptical defects in the form of a one-sided notch oriented at different angles 45, 60, and 90 degrees were subjected to cyclic bending (R=-1). The stress state analysis was performed using local and non-local methods to determine an equivalent amplitude of stress, and then the results were compared with those obtained for smooth specimens.

Flat diamond sliding burnishing surface roughness investigation

The sliding diamond burnishing process is one among many burnishing post-machining processes applied for surface integrity enhancement purposes. This experimental study aims to investigate the effect of burnishing parameters on the surface roughness of the product. Taguchi design was used, and the machining parameters considered were burnishing force, feed rate, and the number of passes with three levels each. C45 steel alloy workpieces were face milled with the same machining variables and their surface roughness was measured before and after the diamond sliding burnishing process. Enhanced surface roughness was achieved with increasing burnishing force and minimum feed rate and higher number of passes.