C45 Steel Research Articles

On the suitability of single-edge notch tension (SENT) testing for assessing hydrogen-assisted cracking susceptibility

Combined experiments and computational modelling are used to increase understanding of the suitability of the Single-Edge Notch Tension (SENT) test for assessing hydrogen embrittlement susceptibility. The SENT tests were designed to provide the mode I threshold stress intensity factor (Kth) for hydrogen-assisted cracking of a C110 steel in two corrosive environments. These were accompanied by hydrogen permeation experiments to relate the environments to the absorbed hydrogen concentrations. A coupled phase-field-based deformation–diffusion-fracture model is then employed to simulate the SENT tests, predicting Kth in good agreement with the experimental results and providing insights into the hydrogen absorption–diffusion–cracking interactions. The suitability of SENT testing and its optimal characteristics (e.g., test duration) are discussed in terms of the various simultaneous active time-dependent phenomena, triaxiality dependencies, and regimes of hydrogen embrittlement susceptibility.

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

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

Microstructural evolution of multilayered AISI 316L-440C steel composites manufactured by laser powder bed fusion

This study presents a systematic study of multilayered steel-steel composites prepared via laser powder bed fusion (L-PBF) in an open-architecture additive manufacturing system equipped with a multiple powder delivery module. Stainless steel AISI 316L powder and high‑carbon stainless steel 440C powder were chosen as the model material system. The printed samples were characterized using optical microscopy, X-ray diffraction, electron backscattered diffraction, energy-dispersive X-ray spectroscopy, X-ray tomography, and micro-hardness to understand the complex manufacturing process and its influence on the microstructure and properties. The evolution of the multilayered structure was assessed, revealing that significantly more pronounced remelting occurs when the 440C powder is deposited on the 316L band, generating a thick 440C/316L transition region and a thin 440C band. Cracks were observed primarily at the transition regions, and were attributed to a “hot cracking” mechanism. The cracks were associated with significant chemical segregation along the grain boundaries at these regions, which exhibit intrinsically higher hot cracking susceptibility than the single-material bands. This was particularly prevalent for mixtures with <50 wt% SS440C (balance AISI 316L), as corroborated by thermodynamic calculations and observed crack locations. The processing-microstructure relationship was discussed in terms of the formation of defects at the transition regions. Challenges associated with crack removal in multi-material systems were discussed and guidelines for manufacturing multi-material, multilayered composites via L-PBF were provided.

Advancing turning performance of C45 steel for marine applications: A comprehensive study on optimizing cutting conditions

Cutting condition is a pivotal factor affecting cutting performance in the turning process, especially in marine engineering, where materials must withstand the challenges of maritime environments. This study presents an experimental investigation of the impact of cutting process parameters on surface roughness, Vicker hardness, and cutting temperature in the turning of C45 steel, a critical material for marine applications. The experiments are meticulously designed based on input parameters, including cutting speed and various cutting conditions (dry, flood, MQL, and nano-MQL), focusing on their relevance to maritime manufacturing. After collecting and analyzing the experimental data, it becomes evident that increasing the cutting velocity significantly reduces surface roughness and temperature, aligning with the marine industry's need for precision and durability. Additionally, Nano-MQL lubrication is the most effective solution for minimizing cutting temperature and improving surface quality. It is a noteworthy advancement for enhancing cutting performance in marine science and engineering. Keywords: Cutting condition, Nano-MQL, surface roughness, temperature

Mechanical, corrosion and tribocorrosion resistance of additively manufactured Maraging C300 steel

This article presents the effect of selected parameters of the additive manufacturing process on the structure of Maraging C300 steel and consequently on its properties: hardness and resistance to abrasive wear, corrosion and tribocorrosion in 3.5% NaCl. The samples were produced with laser beams of 300, 350 and 400 W. Materials with different average microhardnesses of 436, 374 and 315 HV0.05 have been manufactured, respectively. Comparative evaluation of wear resistance on a ball-on-plate model node bench was carried out. Tests were performed under tribocorrosion conditions and for only mechanical forcing. Corrosion resistance was estimated from polarization curves. The article summarizes tribocorrosion model for Maraging C300 steel, which takes into account the effect of grain size on the course of elementary wear processes, especially on the formation of friction and corrosion synergy. The results show that reducing the power of the laser beam in the manufacturing process of Maraging steel produces a material with a more fine-grained structure. Smaller grains provide higher hardness and greater resistance to abrasive wear. Unfortunately, at the same time, the corrosion resistance in 3.5% NaCl is worse. The different effect of grain size on abrasion intensity and corrosion wear means that under tribocorrosion conditions, increasing microhardness does not reduce volumetric wear. The least tribocorrosion wear is provided by the material produced by a 350 W laser beam, amounting to 1.34 × 10−3 mm3.

Theoretical and numerical modeling of the effect of damage and dynamic strain aging on the plastic response of C45 steel alloys

A constitutive model for C45 steel alloys is proposed in this work by integrating the effect of damage and a specific phenomenon, so-called dynamic strain aging. For damage modeling, an energy-based isotropic damage model is implemented within a frame of continuum damage mechanics. The total stress is decomposed into athermal and thermal elements. The former includes the additional term for dynamic strain aging. This term is conceptually inspired by the probabilistic nature of dynamic strain aging, and its derivation is micromechanics-based. Both athermal and thermal components are defined as a function of temperature, equivalent plastic strain, and equivalent plastic strain rate because the occurrence and characteristics of dynamic strain aging are dependent on these factors. A finite element solution for the developed model is addressed additionally to further investigate the characteristics of plastic-damage behaviors and dynamic strain aging. The numerical results are compared to the experiments and theoretical predictions for its validation. The modified model developed in this work has largely reduced the number of fitting parameters compared to the previous model originally developed by the authors in 2019. Nevertheless, predictions from the proposed model still capture the experimental data accurately.

Optimization of Sustainable Production Processes in C45 Steel Machining Using a Confocal Chromatic Sensor

Metal machining production faces a myriad of demands encompassing ecology, automation, product control, and cost reduction. Within this framework, an exploration into employing a direct inspection of the machined area within the work zone of a given machine through a confocal chromatic sensor was undertaken. In the turning process, parameters including cutting speed (A), feed (B), depth of cut (C), workpiece length from clamping (D), and cutting edge radius (E) were designated as input variables. Roundness deviation (Rd) and tool face wear (KM) parameters were identified as output factors for assessing process performance. The experimental phase adhered to the Taguchi Orthogonal Array L27. Confirmatory tests revealed that optimizing process parameters according to the Taguchi method could enhance the turning performance of C45 steel. ANOVA results underscored the significant impact of cutting speed (A), feed (B), depth of cut (C), and workpiece length from clamping (D) on turning performance concerning Rd and KM. Furthermore, initial regression models were formulated to forecast roundness variation and tool face wear. The proposed parameters were found to not only influence the machined surface but also affect confocal sensor measurements. Consequently, we advocate for the adoption of these optimal cutting conditions in product production to bolster turning performance when machining C45 steel.

EFFECT OF CEREAL SEED CONTRIBUTION TO THE WEAROF SELECTED MATERIALS USED TO PRODUCE SCREWCONVEYOR BLADES

This paper presents the analysis of the process of structural material wear by cereal seeds. Two steel gradeswere subjected to testing: C45 and low-alloy steel with a micro-addition of boron. The experiment wasconducted under laboratory conditions by the “rotating bowl” method. Wheat and maize seeds were usedas an abrasive. During the testing, analyses of specimen weight and volume loss as a function of the frictiondistance were carried out. An analysis of the test material surface was conducted as well.The study results show that the C45 steel worn in maize grains exhibited a weight loss greater by 20% thanthat for the wear in wheat grains. For the abrasion-resistant steel, the difference was 22%. In both abrasivemediums, the C45 steel wore to a greater extent than the abrasion-resistant steel. For the maize grain abrasive,the weight loss value was approx. 1.5 times higher than that for the C45 steel. Similar correlations were notedfor the wheat abrasive. The abrasion-resistant steel had a wear rate approx. 1.6 times lower than the C45 steel.The dominant wear types observed on the surfaces of the test steels include ridging and micro-cutting.

Effect of Al-Cu-Fe Quasicrystal Particles on the Reinforcement of a Polymer–Matrix Composite: From Surface to Mechanical Properties

We examined the effect of Al59Cu25Fe13B3 (at.%) quasicrystalline (QC) reinforcement particles on the mechanical and surface properties of a polymer-matrix composite by applying a technical polymer polyphthalamide (PPA). The observed increase in the tensile Young’s modulus ranged from 1810 MPa for the pure polymer to 4114 MPa for the composite with a QC filling of 35 vol.%. The elongation at fracture decreased with the filling fraction, being equal to 16.9% for a pure polymer and dropping to 4.8% for the composite with a QC filling of 35 vol.%. The same trend was noticeable with flexural Young’s modulus, which ranged from 100 MPa for a pure polymer to 125.5 MPa for the composite with 35 vol.% of QC. It was found that the increase in the mechanical strength led to a simultaneous increase of brittleness, which was reflected in a decrease of the impact strength for a pure polymer from 98.5 kJ/m2 to 42.4 kJ/m2 for composites with a QC filling of 35 vol.%. In contrast, when filled with 5 vol.% of QC, the impact strength increased by 8%. The friction coefficient against 100C6 steel dropped from 0.15 for pure PPA down to 0.10 for 5 vol.% of the QC filling, followed by an increase to 0.26 for further QC fillings up to 35 vol.%. Interestingly, a local minimum of friction was achieved at filling factors between 5 to 20 vol.% of QC. Independently, a clear surfenergy minimum was also found for the composite material with 20 vol.% of QC filling associated with a net drop in the polar component of the surfenergy. Surfenergy refers to the surface energy related to the top of the oxide layer under ambient conditions. We hypothesise that this is related to the percolation threshold at about 13 vol.% QC, reflected in the observed behaviour of both the friction coefficient and surfenergy. For the pure QC annealed in air for 1 h at 500 °C significant wear tracks were observed accompanied by a wear debris formation. On the other hand, a pure polymer exhibited slightly visible wear tracks with no apparent debris formation, and for the composites with different QC filling factors, the wear traces were barely visible with negligible debris formation.

The Effect of Chemical Composition on the Microstructure and Properties of Multicomponent Nickel-Based Boride Layers Produced on C45 Steel by the Hybrid Method

Layers of iron–nickel Fe-Ni-B-type borides were produced on C45 steel using a new hybrid treatment variant which combines boriding under glow discharge conditions with galvanic nickel precoating. The aim was to investigate whether these layers could constitute an alternative to the previously developed multicomponent Fe-Ni-B-P-type layers produced by a hybrid treatment variant using chemical nickel precoating. The basis for assessing the effects of both alternative treatments was a comparative analysis of the microstructure and performance properties of three model boride layers: iron–nickel boride layers of the Fe-Ni-B and Fe-Ni-B-P types, and reference iron Fe-B-type boride layer. It was demonstrated that the new variant of hybrid treatment produces Fe-Ni-B layers with the highest thickness, slight porosity, the optimal structure of Ni2B boride in the near-surface zone and the best performance properties. These layers show good adhesion, a much higher hardness of 2200 HV0.05 and near-surface compressive stresses of −450 MPa. Fe-Ni-B-P layers show slightly better wear resistance for higher loads, but like Fe-B layers, they are susceptible to spalling. It was demonstrated that Fe-Ni-B layers produced using boriding with nickel galvanic steel precoating could find application in heavy-duty elements of nanobainitic steel processing.

Effects of metal element doping on the lubrication behaviors and mechanisms of gallium-based liquid metals

Gallium-based liquid metals (GLMs) are a novel high-end lubricant with low friction coefficient and excellent load-carrying capacity. This paper aims to improve the lubrication properties of GLMs by regulating the frictional interfaces. Six types of GLMs doped with Zn, Mg, Bi, Cu, Ti, or Sc elements are prepared respectively, and the effects of metal element doping on the lubrication behaviors and mechanisms for AISI 440C steel self-mated pairs are investigated in the mixed lubrication regime with a ball-on-three-plate setup. Doping 1 wt% Zn or Cu elements can improve the lubrication properties, with the friction coefficient reduced by 20.3 % and the wear rate reduced by 55.1 % compared with those under eutectic Ga/In/Sn lubrication. However, doping Ti, Sc, Mg, or Bi all reduce the lubrication properties. Doping Zn improves the lubrication properties of GLMs by promoting the adsorption of gallium on the frictional interfaces. Conversely, doping Bi inhibits the adsorption of gallium. The improvement in the lubrication properties of Cu-doped GLM is attributed to the formation of low-hardness CuGa2 particles. The doping of Ti or Sc generates high-hardness TiGa3 or ScGa3 particles, causing three-body abrasive wear. The doping of Mg generates a large number of Mg2Ga5 particles, seriously disrupting the stable lubrication.

The Selection of Cutting Speed to Prevent Deterioration of the Surface in Internal Turning of C45 Steel by Small-Diameter Boring Bars

The turning of small-diameter deep holes is usually critical when the process of machining is unstable and the use of a special boring bar is often necessary. This paper is focused on the influence of cutting speed with a combination of cutting conditions such as feed and tool overhang on chatter marks, surface roughness and roundness of machined holes. In the experiment, two types of tool material for indexable boring bars were used, namely cemented carbide and steel. These are a group of boring bars used for the internal turning of holes of small diameters with indexable cutting inserts. Monolithic carbide boring bars are already used for internal turning of holes of even smaller diameters. Uncoated turning inserts made of cermet were used. The cutting tests were performed on the DMG CTX alpha 500 turning center. In the case of the steel boring bar, decreasing the cutting speed really led to an increase in the quality of the surface roughness and reduced the formation of chatter marks and large chatter marks. The cemented carbide boring bar also followed a similar trend, but it should be noted that the overall effect was not so great. This means that increasing the cutting speed makes the cutting process less stable and, vice versa, lower values of cutting speed reduce the formation of chatter marks and the related deterioration of the surface quality. The occurrence of chatter is directly related to the increase in the surface roughness parameters Ra and Rz of the machined surface. It can be stated that the dependence of roundness deviations on cutting speed values has a similar character to the results of the measured surface roughness values. Therefore, if the cutting speed is increased, it will make the cutting process less stable; this is also indirectly reflected in larger roundness deviations. However, it is necessary to state that this phenomenon can be observed in turning holes with small diameters using the steel boring bar, where the unstable cutting conditions materialized in the form of chatter marks.

Evaluation of Specific Wear Coefficient of Sliding Contact Pairs through Tribological Experiments

In fuel handling machine of Prototype Fast Breeder Reactor, colomony-5 is extensively used for hardfacing of rubbing surfaces. To avoid the challenges associated with hardfacing of the components, it is proposed to eliminate hardfacing by using a forged component of a suitable material. 440C steel is a candidate material for this application. Hence, experiments were conducted to evaluate the tribological properties of 440C steel under various conditions seen during the operation. The tests were carried out using pin on disc tribometer by varying the load from 10-20 N and sliding speed from 5-30 mm/s. Friction and specific wear coefficients were evaluated from the experiments. Besides, Global Incremental Wear Model (GIWM) was used for prediction of wear behaviour of the steel.

The Use of SAW, RAM and PIV Decision Methods in Determining the Optimal Choice of Materials for the Manufacture of Screw Gearbox Acceleration Boxes

This article investigates material selection for components in worm gear reduction gearboxes, focusing on the worm shaft, gearbox casing, and worm gear body. The screw shaft’s and worm gear body’s material selection involved evaluating six criteria: hardness, tensile strength, yield strength, relative elongation, relative contraction, and impact strength. Gearbox casing materials were selected based on five parameters, including tensile strength, yield strength, relative elongation, impact strength, and hardness. The authors employed three Multi-Criteria Decision-Making (MCDM) methods, Simple Additive Weighting (SAW), Root Assessment Method (RAM), and Proximity Indexed Value (PIV) to assess material choices. Various methods, including Entropy, Logarithmic Percentage Change-driven Objective Weighting (LOPCOW), and Equal, determined weights for the criteria. Remarkably, consistent optimal material types emerged across all MCDM and weight determination methods, showcasing the robustness of the results. For screw shafts, C35 steel was identified as the optimal type. GC120- 04 stood out among nine materials for gearbox casing production. C35CrMo was determined as the best type among eight steel types for manufacturing the worm gear body. In summary, this study provides a comprehensive and objective approach to material selection for worm gear reduction gearbox components, offering valuable insights for decision-making in the mechanical engineering industry.

Sequential estimation of high temperatures of liquid metals by using particle filter methods

This work follows up our previous studies dedicated to the estimation of the transient temperature of niobium and 100c6 steel samples, in ranges that include solid and liquid phases, as well as phase changes. In the experimental setup, a metallic sample of few millimeters is aerodynamically levitated and then heated by a powerful laser, while a collimator focused on the sample collects the radiative flux that is split towards five pyrometers of different wavelengths. The measured spectral fluxes are used in an inverse analysis to estimate the sample temperature. Difficulties in the inverse problem solution related to the dependence of the sample emittance with temperature and wavelength could be overcome by reducing the number of model parameters using a simple linear variation of the emittance with respect to the wavelength. In this work the transient temperature of the sample is estimated sequentially by solving a state estimation problem with two algorithms of the particle filter method, namely: the Sampling Importance Resampling (SIR) and Auxiliary Sampling Importance Resampling (ASIR) algorithms. Results obtained with these algorithms and the radiative spectral fluxes exhibited small discrepancies with respect to the temperature measurements of a reference bichromatic pyrometer.

Analysis the Influence of Pressure Distribution on Exhaust Manifold Using FEM

Abstract: In this paper the 3D model of the exhaust manifold was realized using Autodesk Inventor Professional 2024 and finite element analysis was performed, in order to determine the state of stress and deformation, by applying restrictions and loads conditions. The materials chosen, for exhaust manifold, was in accordance with the specialized literature. The materials taken for static analysis was Stainless Steel 440C and Iron Gray Cast. Following the comparative study for the two models, it can be specified that the importance of the material for the construction of the exhaust manifold depends on the mass properties and their design

Designing hydrogen-free diamond like multilayer carbon coatings for superior mechanical and tribological performance

Diamond like carbon (DLC) coatings are extensively employed for their outstanding mechanical and tribological properties. To overcome the inherent high residual stress, therefore brittleness, DLC coatings with multilayer architecture were developed in the form of stacking alternate hard and soft layers to avoid premature failure under severe loading conditions. The current study was designed to investigate the impact of bilayer thickness (hard & soft) on wear of multilayer DLC particularly at high contact stress (2.0 GPa, 2.7 GPa, 3.0 GPa, 3.4 GPa). Seven DLC multilayer (1:1 bilayer ratio) samples with 1, 2, 5, 10, 20, 40, 80 bilayers were deposited on 440C steel and the overall coating thickness was mainatined at ∼1 µm. Moreover, the bilayer thickness effect was determined on mechanical, scratch adhesion and structural properties. Transmission electron microscope (TEM) was used to visualize discrete hard and soft layers in 80 bilayers (∼6 nm thin layer). G peak suppression and ID/IG increment were observed with reduction in bilayer thickness. Hardness, modulus, elastic strain to failure (H/E), plastic deformation resistance (H3/E2) and residual stresses showed an inverse relation with bilayer thickness. Furthermore, micro scratch adhesion decreases with layer thickness reduction. Only 100 nm and above bilayer thickness samples (1, 2, 5, 10 bilayers) could survive under high contact stress while the other three (20, 40, 80 bilayers) showed brittle failure using pin-on-disc tribometer. Additionally, 10 bilayers (100 nm thickness) produced the minimum wear (∼7.9 ×10−8 mm3/Nm) at 80 N.

Research the Dimensional Accuracy of C45 Steel Ring Forgings Produced by Radial Rolling.

The rolling process of rings is a commonly used method for producing annular forgings. There are two primary types of this process: radial-axial rolling and radial rolling. This article presents the research results regarding the latter, in which obtaining a product with the assumed dimensions constitutes a major problem. In industrial practice, the process parameters are based on the experience of technologists and/or by trial and error. This is why the authors considered it justified to undertake the research aimed at determining the influence of the main process parameters, that is, preform temperature and tool speed, on the shape and dimensions of the cross-section, which determine the internal and external diameters of the rolled ring. The research was based on numerical simulations and experimental studies. The results obtained proved that the higher the feed speed of the main roll, the greater the change in the cross-sectional height during rolling, and the smaller the cross-sectional deformation (the so-called fishtail). Nevertheless, a higher preform temperature reduces the final height of the ring and reduces cross-section deformation. On the basis of the obtained test results, guidelines for the process design were postulated, considering the influence of temperature and speed parameters on the final dimensions of the forging and the dimensions of the preform.

Neural metamodels and transfer learning for induction heating processes (TEAM 36 problem)

The authors explore the possibility of applying a convolutional Naeural Network (CNN) to the solution of coupled electromagnetic and thermal problem, focusing on the classical problem of induction heating systems, traditionally solved by resorting to Finite Element (FE) models. In fact, FE modelling is widely used in the design of induction heating systems due its accuracy, even if the solution of a coupled nonlinear problem is expensive in terms of computational time and hardware resources, notably in 3D analysis. A model based on CNN could be an interesting alternative; in fact, CNN is a learning model selected for its excellent ability to converge, even when trained with a limited dataset. CNNs are able to treat images as input and they are used here as follows: given a temperature map in the workpiece, identify the corresponding vector of current, frequency and process heating time; this mapping is a model of the inverse induction heating problem. Specifically, we consider as an example the induction heating of a cylindrical steel billet, made of C45 steel, placed in a solenoidal inductor coil exhibiting the same axial length of the billet (TEAM 36 problem). A thorough heating process is usually applied before hot working of the billet, as in an extrusion process, but this methodology can be applied also in the design of induction hardening processes. First, a CNN has been trained from scratch by means of a dataset of FE solutions of coupled electromagnetic and thermal problems. For the sake of a comparison, a transfer learning technique is applied using GoogLeNet, i.e. a Deep Convolutional Neural Network able to classify images: starting from the pre-trained GoogLeNet, its training has been subsequently refined with the dataset of solutions from FE analyses. When the training dataset contains a limited number of samples, GoogleNet shows good accuracy in predicting the process parameters; in the case of a high number of samples in the training set, namely beyond a threshold like e.g. 1500, both CNNs show good accuracy of the result.

Multifractal parameterization of a periodic surface microrelief formed at the face milling. 2. Distribution of elements volume of surface relief

This study represents the first application of multifractal analysis to characterize spatial microforms’ volumes resulting from face milling on flat surfaces, emphasizing its novelty. Photographs of samples of C35 steel and AA22024 aluminum alloy, subjected to various cutting conditions during milling, were utilized to apply the multifractal approach for describing the machined surface microrelief. Multifractal spectra and their key parameters were computed for the samples’ surfaces generated at various feed rates and cutting depths. It is demonstrated that the characteristic functions of the performed multifractal analysis align with their canonical forms. The results offer compelling evidence that machining results in the formation of a system exhibiting self-similarity and fractal symmetry properties on the specimen’s surface. The practical significance of this research lies in the establishment of quantitative dependences between the parameters of the multifractal spectrum of surface microforms generated during the face milling under varying cutting depths and feed rates. This facilitates the identification of technological and physical factors responsible for observed variations in surface fractal properties. The formation of the multifractal spectra from surface element volumes is discussed in connection with the underlying physical phenomena associated with cutting conditions.