Résumé: Corrosion poses a major challenge to the longevity and performance of steel pipelines, especially those used for hydrocarbon transportation. This study investigates the impact of blackening on the corrosion resistance of API 5L X52 steel, a material widely used for high-pressure applications. Blackening, a surface treatment method, is compared with conventional machining to evaluate its effectiveness in improving corrosion resistance. High-strength steel (HYS) X52-Q was subjected to various blackening conditions, characterized by different feed rates and number of passes. Corrosion resistance was evaluated using electrochemical tests, focusing on parameters such as corrosion potential (E cor ), corrosion current density (I cor ), and polarization resistance (R p ). The results indicate that black oxide coating significantly improves corrosion resistance compared to machining, with polarization resistance (R p ) increasing by 65.98% to 442.53%. The most notable improvement was observed at a feed rate of 400 mm/min and three passes, showing that the number of passes has a more pronounced effect on corrosion resistance than the feed rate. A linear regression model was developed to predict R p as a function of black oxide coating parameters, highlighting the crucial role of the number of passes. These results underline the benefits of black oxide coating in extending the service life of API 5L X52 steel pipelines, providing both economic and operational advantages by improving durability in corrosive environments. Corrosion poses a significant challenge to the longevity and performance of steel pipelines, especially those used for the transportation of hydrocarbons. This study investigates the impact of burnishing on the corrosion resistance of API 5L X52 steel, a widely used material for high-pressure applications. Burnishing, a surface treatment method, is compared with conventional machining to evaluate its effectiveness in improving corrosion resistance. High-strength steel (HYS) samples of X52-Q grade with dimensions of 10 × 10 × 8 mm were subjected to various burnishing conditions, characterized by different feed rates (400 mm/min and 600 mm/min) and varying number of passes (1 and 3). Corrosion resistance was evaluated using electrochemical tests, focusing on parameters such as corrosion potential (E cor ), corrosion current density (I cor ), and polarization resistance (Rp). The results indicate that black oxide coating significantly improves corrosion resistance compared to machining, with Rp increasing from 65.98% to 442.53%. The most notable improvement was observed at 400 mm/min with three passes, where Rp decreased from 4.358 Ω (machined condition) to 23.60 Ω (burnished condition). The results highlight that the number of passes has a more pronounced effect on corrosion resistance than feed rate. A linear regression model was developed to predict Rp based on black oxide coating parameters, confirming the significant influence of the number of passes. These results highlight the benefits of black oxide coating in extending the service life of API 5L X52 steel pipes, offering both economic and operational advantages by improving durability in corrosive environement

Résumé: Quality of products is a major concern for hard machining industry aspects. However, the prediction of surface roughness in the function of the machining parameters is a targeted objective by the majority of researchers due to important industrial interest. This work is a contribution for developing comprehensive analyses of surface roughness models during dry hard turning of cold work steel AISI D2. It is focused on the treatment of predicted surface roughness values in correlation with cutting conditions such as cutting parameters (cutting speed, feed rate, and depth of cut), tools material, tool geometry, workpieces hardness, and machining times in order to establish of orientations for use which applied successfully in the industry from optimal selection of process variables. The approach consists in first conducting a literature survey through collecting and validating surface roughness models together with the corresponding material and also the cutting conditions. Then, results have been tabulated as to permit data mining treatment under data processing software which was developed. As a significant result, a strategic dashboard generating roughness data mining was made available to researchers and industrials. The optimums of parameters which condition the achievement of best machined surface qualities have been selected.

Résumé: To investigate the effect of the slide diamond burnishing process on the mechanical properties of GCR15 steel, an experimental study was carried out. For this purpose, burnished and unburnished specimens have been prepared and compared in fatigue performance, surface roughness, microhardness, and SEM analysis. The burnishing process was carried out at a speed of 560 rpm, a burnishing force of 10 Kgf, a feed rate of 0.074 mm/rev and several passes of 3. Rotary bending fatigue tests were performed on the burnished and unburnished specimens, S–N curves were plotted from a maximum load representing 66% of tensile strength. The findings indicate that the fatigue strength was increased by up to 36% because of slide diamond burnishing compared to the non-burnished case. At lower stress levels, the improvement in fatigue strength is clearly observed. The fatigue curves reveal a slight reduction in the fatigue strength results compared to those reported in the literature, which can be attributed to the specimen’s small shoulder fillet value

Résumé: The present work is a contribution in order to highlight the contradictory efect of machining conditions on wear evolution in the main cutting zone of twist high-speed steel (HSS) grade drill bits. Wear tests have been conducted on annealed and hardened C22 steel according to the planning experience methodology (L8). The input parameters are cutting speed, feed rate, and drill diameter; meanwhile, the output parameters are values of lank and chisel wears related to the tool life. Results show that the tool life of a twist drill depends on both lank wear and chisel wear. Meanwhile, the two wears can be competitive as a function of cutting conditions. For instance, within the three cutting parameters, feed rate is most inluencing, then the cutting speed, and the tool diameter efect is nonsigniicant. In the annealed condition, when feed rate and cutting speed increase, lank wear (VB) and chisel wear (VCH) are faster. That is good agreement with literature review on machinability of steels. The higher the cutting speed and feed rate, the lower the tool life. In the hardened condition, chisel wear becomes increasingly competitive with lank wear and even faster under certain cutting parameters. However, increasing the cutting speed results in lower wear evolution and, consequently, a better tool life. This contradictory efect of cutting speed is unique to drilling operations with HSS steel drill bits. Finally, chisel wear models have been presented to make evidence of their importance for industrial application where drilling hardened steel is required.

Résumé: The present work is a contribution in understanding the effect of quenching and tempering of C22 steel on the tool life of twist high speed steel (HSS) grade drill bits. Experimental investigation has been conducted on annealed and tempered steel according to the planning methodology (L8). The input parameters are cutting regime elements (cutting speed, feed rate and drill diameter) and the output parameter is the tool wear related to tool life. Beyond, the common behavior that suggests that when the feed rate on tool life increases the tool life increases, the most interesting phenomenon is the controversial effect of the cutting speed when drilling the steel in tempered condition. The objective of this contribution then to in make in evidence the benefit effect of quench hardening on drill tool life through exploratory chip microstructure observations.

Résumé: – This work aims to understand the influence of cutting parameters on the twist highspeed steel (HSS) drill bits wear when drilling C35 steel before and after quenching. An experimental investigation has been conducted using the planning experience methodology (L8) on C35 steel in the annealed and hardened states. The input parameters are cutting regime elements, cutting speed (Vc), feed rate (f), and drill diameter (D), while the output parameters are the tool wear related to its tool life. The most interesting phenomenon is the controversial effect of cutting speed when drilling C35 steel in hardened conditions. The drilling life increases with increasing cutting speed for different cutting regimes (1 to 8). In addition, the 20 mm diameter drill related to the high value of the depth of cut (f) has given better life before and after hardening, contrary to the literature on cutting tool life. The analysis of variance (ANOVA) has showed that the feed rate (f) is the most significant factor in the annealed state while it is the depth of cut (ap) in the hardened state. The correlation coefficients R2 determined by the ANOVA before, and after quenching, are very satisfactory, and testify the good adequacy of the proposed model. Copyright © 2021 Praise Worthy Prize S.r.l. - All rights reserved

Résumé: The present work is a contribution in understanding the machinability of hardened C22 steel under drilling operations using twist high-speed steel (HSS) grade drill bits. Experimental investigation has been conducted on annealed and hardened C22 steel according to the planning experience methodology (L8). The input parameters are cutting regime elements, cutting speed, feed rate, and drill diameter; meanwhile, the output parameter is the tool wear related to tool life. Apart from the common observation that tool life decreases when the cutting speed increases, the most interesting phenomenon is the controversial effect of the cutting speed when drilling the steel in hardened condition. The latter has been assessed through exploratory chip microstructure observations

Résumé: Dans ce travail sont exposés les résultats d’une investigation expérimentale sur le comportement à l’usure des forets hélicoïdaux en acier rapide lors du perçage de l’acier C18. Les essais de perçage ont été effectués avec des forets de différentes longueurs et de différents diamètres. La longueur du perçage est d'environ 80 mm en présence d'une lubrification abondante et d'un cycle de débourrage adopté. La méthodologie entreprise pour la réalisation des essais est celle de planification des expériences. Le paramètre de sortie étudié est l'usure (durée de vie du foret). Les paramètres d’entrée investigués sont la vitesse de coupe, l’avance et le diamètre du foret. Le critère retenu de l'usure admissible est VB=0,5 mm suivant la surface en dépouille principale. Les résultats montrent que l'acier C18 se caractérise par une bonne usinabilité (la durée de vie T varie de 19 à 495 min) et ceci pour toutes les combinaisons du plan d’expérience étudié.

Résumé: L'objectif de cette étude est la détermination de l'usinabilité de l’acier C18 avant et après trempe, lors des opérations de perçage. Pour atteindre cet objectif, nous lui avons fait subir un recuit d'homogénéisation puis une trempe à 900°C suivie d'un revenu. Des opérations de perçage ont été réalisées à l’aide de forets hélicoïdaux en acier rapide de différents diamètres. La longueur du perçage est d'environ 60 mm en présence d'une lubrification abondante et un cycle de débourrage adopté. Les essais ont été réalisés conformément à la méthode de planifications des expériences. La réponse de sortie est analysée en termes de l’usure de l’outil et l’état de surface usinée. Les résultats obtenus montrent que l’usinabilité de l’acier C18 à l’état non trempé est étroitement liée aux paramètres de coupe utilisés et se traduit par une tenue du foret qui peut varier entre 19 et 495 min avant d’atteindre l’usure admissible. Par ailleurs l’état de surface qui en résulte est relativement rugueux avec Ra 3,5 à 6,11 μm. À l’état trempé ce dernier s’améliore progressivement pour diminuer jusqu’à Ra 2,71 μm. L’effet de la microstructure semble être primordiale sur l’usinabilité de l’acier puisqu’il il a été remarqué que contrairement à l’état non trempé, l’augmentation de la vitesse de coupe Vc favorise une meilleur usinabilité en réduisant l’usure lors du perçage de l’acier trempé.

Résumé: Mesurer une grandeur physique consiste à lui attribuer une valeur quantitative en prenant pour référence une grandeur de même nature appelée unité. Ce cours vise l'acquisition des fondements technologiques sur la métrologie générale et industrielle les notions acquises permettrons de reconnaitre l’ensemble des moyens techniques utilisés et les opérations ayant pour but de déterminer une valeur d'une grandeur, prendre connaissance des différents organismes et systèmes régissant la science de la mesure.

Résumé: Abstract: This article is dedicated to the statistical modelling of the effect of cutting parameters on the roughness of the machined surface when drilling C22 steel using HSS twist drills in the annealed and hardened condition. The tests were carried out in accordance with the experimental design methodology (L8). Cutting speed, feed rate and drill diameter are the main elements of the cutting regime representing the input parameters of the test, while the roughness of the machined surface is considered as the response criterion. The results show that the metallurgical aspect of the steel and the cutting parameters have a remarkable influence on the good finish of the machined surface; increasing the cutting speed improves the roughness, while it deteriorates with increasing feed speed and drill diameter. Increasing the feed speed increases the height of asperities on the machined surface, and large diameters require high cutting forces that affect the stability of the machining system. On the other hand, increasing the cutting speed stabilises the system by reducing the cutting forces, which favours chip flow. The roughness obtained after heat treatment is significantly better than that of annealed parts; the steel after quenching has a finer microstructure, which reduces deburring of the material during cutting. The same applies to low rates of elastic deformation, which allow clean, burr-free breakage. In addition, hard materials with fine microstructures mean that chip shear is accompanied by much finer particles being torn off, contributing to improved surface finish. This study has produced predictive mathematical models that correlate well with the experimental results and can be used as tools for industrial applications.

Résumé: Abstract: The paper focuses on the vibrations responses of sandwich panels constituted of different types of viscoelastic core materials under the effect of a moving load in a thermal environment. The present approach is based on the finite element method using the variationnelle formulation of Hamilton’s principle with the virtual displacement principle. However, the complexity of constructing the model basis by solving the eigenvalue problem, mainly due to the frequency dependence of the viscoelastic properties and the stiffness matrix, requires the use of the asymptotic numerical method “ANM” combined with the automatic differentiation “AD” algorithm. This numerical approach presented here is considered a typical approach well suited to solve the vibration problem of sandwich structures with viscoelastic core. First, an evaluation of the state of stress in the different layers constituting the sandwich are discussed. However, the response of sandwich structures with viscoelastic cores considered frequency and temperature dependent under the action of a moving load are deeply investigated. The effect of the variation of the viscoelastic damping and the temperature is very significant on the stress state of the viscoelastic layer and forced vibration responses

Résumé: Abstract: The aim of this paper is to present a simpliied numerical approach to study the vibro-acoustic responses of structures with PCLD “Passive Constrained Layer Damping” treatment in the thermal environment, taking into account the frequency and temperature dependence of the diferent viscoelastic behavior laws. The modal stability procedure MSP is based on the finite element method in order to discretize and formulate the equation of motion. The asymptotic numerical method “ANM” is applied to approximate the solution of complex eigenvalue problems and construct the modal basis. The variability of the frequency responses is evaluated by a Monte Carlo simulation (MCS) combined with MSP and ANM to evaluate the stochastic behavior of a sandwich beam with random properties. The comparison with the direct frequency responses (DFR) demonstrates that the results are highly satisfactory in terms of the validity of the present MSP approach. A comparative study of viscoelastic behavior models was carried out to evaluate their damping properties provided to the structure. The viscoelastic materials provide signiicant damping particularly for amplitudes corresponding to the high frequencies. This is in contrast to the responses obtained without the viscoelastic layer. The obtained results show the importance of viscoelastic damping, which has a signiicant efect on the vibroacoustic behavior, implying the improvement of the damping of the structure, especially for large frequencies and high temperatures.

Résumé: In this work, the results of an experimental investigation are presented to put into evidence the wear evolution of chisel and main cutting edges of high speed steel helical drills (HSS) during the machining of hardened and unhardened C22 steel. To do so, a series of tests was carried out according to the experimental design methodology. The investigated output parameter is the tool wear (lifetime) whereas, the input parameters are the cutting regime elements (cutting speed, feed rate and drill diameter). Machining was performed in the presence of an abundant lubrication. Unlike ISO standard (3685: 1993), stating that the criterion of permissible wear (VBmax = 0.5mm) to determine the tool lifetime is that of the major flank face (main cutting edge), it is found that for some experimental design regimes the increase in speed of the wear of the chisel cutting edge is higher than that of the main cutting edge; i. e., a more intense wear grows earlier on another cutting edge of the active part of the drill than the standardized one. Thus, the permissible wear criterion has to be taken into account when determining the lifetime of cutting tool. The analysis of the obtained results also reveals that the wear of the chisel cutting edge is more intense for the regimes working with low feeds and low cutting speeds. Meanwhile, we note that machining with higher cutting speeds and low feed rates contributes to reduce wear on the chisel cutting edge. 

Résumé: Drilling is a complex machining operation. The latter comes from the fact that the various points of the cutting edge of the drill work under very varied cutting conditions. Indeed, the cutting speed at the center of the drill bit is almost equal to zero, where the removal of the material (chip) is mainly by extrusion. Then, as one moves away from the center (along the cutting edge), the cutting speed increases gradually to its maximum value at the periphery of the drill bit. On the cutting edges material removal occurs by shear in the same manner as for turning and milling tools, with the cutting speed and rake angle varying with distance from the drill center. Furthermore, the cutting takes place in a confined environment inside the part, which makes it impossible to observe the chip flow process. Chip evacuation from the cutting zone is also confronted with countless difficulties (excessive friction with the machined surface of the hole, intense heat release, blocking and braking, forces and cutting moments, etc.). Access of the lubricating and cooling liquid in the cutting zone is hampered by accumulation and reverse flow of the chips. All this leads to the generation of stresses of thermal and mechanical solicitations on the active part of the drill bit, which considerably influences its wear resistance behaviour .

Résumé: The study of the helical drill wear phenomenon assumes the knowledge of the various factors that are required to cause their damage. Among these factors, we mention those of the cutting regime such as speed (Vc), advance (f) and depth of pass (ap). For our case it is the diameter of the drill (d), the geometry of the tool (r, α, β, γ, x, ε ...) and the characteristics of the material used (HB, Rr,% C ,% S, ...), as well as the working conditions (machine, lubrication ...), All these factors constitute the input parameters of the machining system. The holding, the precision, the efforts etc ... present the parameters of exit The objective of this study is statistical modeling of the life of HSS drills. Two series of long-term tests were performed on unalloyed steel C22 and HV22. The length of the hole is approximately 80 mm and 10 to 20 mm in diameter, in the presence of an abundant lubrication of 2.5 l / min and an adopted cleaning cycle. The methodology undertaken for the realization of the tests is that of the planning of the experiments. The factor studied is the wear (lifetime of the drill) on the different cutting zones. The criterion of acceptable wear retained is 0.5 mm depending on the undercut surface. Statistical analysis (ANOVA) allowed the detection of the predictive model of the service life (T) according to the main effects and their interactions. The results show that the service life of the tool for different machining conditions varies between 19 and 495 min.

Résumé: The purpose of this work is to study the quenching effect on C18 steel machinability in drilling. For this reason, a comparative experimental study was conducted on a non-hardened and tempered workpiece. Cutting tools used are drills of high speed steel (HSS) grade. The tests are performed according to the planning methodology (L8). Machining was carried out in the presence of an abundant lubrication. The input parameters are cutting regime elements (cutting speed, feed rate and drill diameter). The output parameter is the tool wear (tool life). The results show that when drilling tempered C18 steel, drill wear decreases with the increase of cutting speed. This latter improves machinability. This is in stark contrast with the results obtained during the drilling of the same non-hardened C18 steel (annealing). It should also be noted that this phenomenon is observed especially for high cutting speeds. A deep analysis was carried out to explain the physical phenomenon occurring in the cutting zone.