Publications internationales
Résumé: The objective of this research is to study the mechanical behavior of chrome molybdenum steel subjected to a mechanical surface treatment.
Résumé: The relentless pursuit of a competitive edge in today’s market compels manufacturers to prioritize high-quality product surfaces. This focus extends beyond aesthetics, as surface finish significantly impacts a product’s functionality. Resistance to corrosion, wear, and fatigue are all heavily influenced by this crucial element. Burnishing emerges as a cost-effective solution for enhancing surface quality, making it a mainstay in industries like aerospace, biomedical, and automotive. By bolstering component reliability and performance, burnishing extends product lifespans and minimizes maintenance requirements. This study delves deeper into this topic, presenting an experimental investigation into the application of diamond sliding burnishing on AISI 52100 steel. The main objectives are to investigate the effects of burnishing parameters, such as force (py), number of passes (np), and feed (f), on surface roughness (Ra) and microhardness (Vickers). Then, a multi-objective optimization was carried out using the desirability function (DF) approach to minimize surface roughness (Ra) and simultaneously maximize microhardness. A mathematical modeling based on the response surface method was performed. The ANOVA method was used to quantify the effects of burnishing parameters as well as their interactions on surface quality and microhardness. For this purpose, a Taguchi L27 plan was adopted for experimental trial planning. The effect of burnishing on surface quality and microhardness was also investigated, it is noted that an improvement of 92 and 117% were recorded, respectively, for surface roughness and microhardness. The multi-objective optimization performed have been given the optimal burnishing parameters, using these parameters, the fatigue life of the steel increased up to 120%. Fracture analysis of fatigue failure faces revealed that burnishing produces fine striations and elongated cups on the fractured surface. In addition, the process offers a more extended fracture zone where the fractured area (AF) occupies up to 61% of the total cross section (At).
Résumé: Degradation caused by corrosion is a major problem for S235JR steel and is responsible for many failures. Ball burnishing is a superficial mechanical finishing treatment that improves surface quality as well as its mechanical properties. The aim of this experimental work is to study the influence of this process on the surface quality and corrosion behavior of S235JR steel. The response surface method (RSM), based on Box-Behnken experimental design, was used to minimize the surface roughness, which has a significant influence on corrosion resistance. “Ra” and “Rz” roughness measurements, as well as 3D surface topography observations, were carried out. Furthermore, the subsurface microhardness distribution was examined, and an X-ray diffraction analysis was performed. The polarization technique (Tafel) and electrochemical impedance spectroscopy (EIS) were used to evaluate corrosion resistance. Finally, analysis by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) was carried out before and after the corrosion tests. The results showed that burnishing force and ball diameter are the main parameters influencing roughness. The optimal regime reduced roughness “Ra” and “Rz” by more than 96% and 97% respectively, producing a smooth and uniform topography. XRD analysis revealed surface grain refinement without phase change. The subsurface microhardness increased to a depth of 40 μm, suggesting a burnished layer of equivalent thickness. Electrochemical corrosion tests and SEM observation showed that the corrosion resistance of the burnished surface was significantly improved, mainly attributed to grain refinement.
Communications internationales
Résumé: The interest of mechanical engineering is the realization of mechanical systems with the longest possible lifespan and operating reliability. This can be obtained by improving the geometric performance of the products which are generally linked to the reduction of dimensional tolerances and the most regular surface conditions. In this context, we consider a chromium molybdenum alloy steel, to which we will examine its behavior to wear by abrasion of surfaces produced by two manufacturing processes, in this case, finishing by a turning operation and finishing by mechanical treatment (TMS). The project was carried out using methods based on an experimental strategy making it possible to determine initially and by simulation using experimental plans, the parameters of the turning regimes offering the varieties of roughness to be considered. Samples were made with surfaces with high roughness values (maximum), others with low roughness values (minimum), some of which were treated with TMS. These varieties of surfaces of different qualities were subjected to the wear test by abrasion on a suitable machine by setting the parameters (nature of abrasive, load, path and speed). The results obtained showed the effect of the surface quality on the wear resistance of the material considered and which are in agreement with certain works presented in the bibliography.