Mohamed Boujelbene

High-Power Laser Cutting of Steel Plates: Heat Affected Zone Analysis

The thermal effect of CO2 high-power laser cutting on cut surface of steel plates is investigated. The effect of the input laser cutting parameters on the melted zone depth (MZ), the heat affected zone depth (HAZ), and the microhardness beneath the cut surface is analyzed. A mathematical model is developed to relate the output process parameters to the input laser cutting parameters. Three input process parameters such as laser beam diameter, cutting speed, and laser power are investigated. Mathematical models for the melted zone and the heat affected zone depth are developed by using design of experiment approach (DOE). The results indicate that the input laser cutting parameters have major effect on melted zone, heat affected zone, and microhardness beneath cut surface. The MZ depth, the HAZ depth, and the microhardness beneath cut surface increase as laser power increases, but they decrease with increasing cutting speed. Laser beam diameter has a negligible effect on HAZ depth but it has a remarkable effect on MZ depth and HAZ microhardness. The melted zone depth and the heat affected zone depth can be reduced by increasing laser cutting speed and decreasing laser power and laser beam diameter.

Analysis of cut surface quality of sheet metals obtained by laser machining: thermal effects

Abstract During laser cutting, the heat caused by cutting has thermal effects on the cutting surface. This results in a hardening zone directly at the cut edge and an adjacent tempering zone. These zones are often associated with undesirable effects such as surface cracking and fatigue resistance. In the present study, high-power CO2 laser cutting of steel sheets is considered and the thermal influence of laser cutting and its main operating parameter, laser power, on the microhardness beneath the cutting section is examined using Vickers microhardness tester. The microstructure changes of the cut edge surface and of the cut surface are investigated using optical and electron scanning microscopes. The results show that laser cutting has a thermal effect on the surface microstructure and on the microhardness beneath the cut section. The microstructure and microhardness of the cut edge are affected by the main input laser cutting parameter, the laser power. Also the microhardness of the affected zone depends on the value of laser power. Microstructure analysis shows that high-power laser cutting leads to the formation of cracks and the average size of grains of the heat affected zone increases with laser power.

Effect of Laser Beam Diameter on Cut Edge of Steel Plates Obtained by Laser Machining

Laser cutting is a thermal process which is used contactless to separate materials. In the present study, high-power laser cutting of steel plates is considered and the thermal influence of laser cutting on the cut edges is examined. The microstructure and the microhardness of the cut edge are affected by the input laser cutting parameter: laser beam diameter. The aim of this work is to investigate the effect of the laser beam diameter on the microhardness beneath the cut surface of steel plates obtained by CO2 laser cutting. The cut surface was studied based on microhardness depth profiles beneath the machined surface. The results show that laser cutting has a thermal effect on the surface microstructure and on the microhardness beneath the cut section. Also the microhardness of the hardening zone depends on the laser beam diameter.

Effects of Laser Cutting Main Parameters on Microhardness and Microstructure Changes of Stainless Steel

Laser cutting of materials is becoming the preferred method of cutting. It has many advantages over conventional machining techniques such as better quality of cuts, quick and accurate cutting. The objective of this work is to investigate the effect of the main input laser cutting parameters, laser power and cutting speed, on the microhardness of stainless steel sheets obtained by CO2 laser cutting. The experimental tests were performed at various laser powers and cutting speeds. The cut surface was studied based on microhardness depth profiles beneath the machined surface. In order to investigate the metallurgical alterations beneath the cut surface, the microstructure was observed by using scanning electron microscopy. The results show that the microhardness and the surface microstructure are affected by laser cutting. Laser cutting leads to the formation of periodic striations and cracks. Also the main parameters of cutting, laser power and cutting speed, have an effect on surface microstructure and microhardness.

Recycled Ti-17 Based Composite Design; Optimization Process Parameters in Wire Cut Electrical Discharge Machining (WEDM)

This work present a comprehensive study on the effect and optimization of machining parameters on the kerf (cutting width) and material removal rate (MRR) in wire electrical discharge machining (WEDM) process by using the response surface methodology (RSM) and Taguchi method. The experimental studies were conducted under varying parameters. The main input parameters on this model are the cutting parameters such us pulse on time (Ton), servo voltage (U), Speed of advance or feed rate (S) and injection pressure or flushing pressure (P). Recycled Titanium based composite (an alloy Ti17) was used for machining operations and the combined effects of cutting parameters on the material removal MRR rate and kerf were investigated while using the analysis of variance ANOVA. Mathematical models were used for the objective of minimum kerf and maximum MRR, Cut edge surface analysis was carried out using an optic microscope and Scanning Electron Microscope (SEM) to evaluate the kerf.

Optimization of Surface Integrity of Titanium-Aluminum Intermetallic Composite Machined by Wire EDM

This study investigate the influence of the machining parameters on Ti-Al intermetallic composite based using a wire electrical discharge machining. This process is typically used for very hard material, which are hard to machine using a more traditional process. The aim of the work is to optimize the integrity of surface of Ti-Al intermetallic composite machined by WEDM. The first step is defined the machining parameters of the process: Start up voltage U, Pulse on time Ton or T, advanced speed S and flushing pressure P (pressure of injection of dielectric) are chosen to determine their effects on surface roughness Ra. The second step is using integrated method, which mixed Taguchi method and response surface methodology RSM, the RSM model was developed as a tool to predict the integrity of surface of Ti-Al intermetallic composite machined by WEDM. The significance of the machining parameters was obtained using analysis of variance (ANOVA) based on S/N ratio, which show that flushing pressure P, Pulse on Time T and Voltage U were the most significant parameters. Microstructure of surface and subsurface, cracks, craters, and debris and roughness surface of the samples machined at the different condition has been realized by scanning electron microscopy (SEM), and 3D-Surfscan. The integrate method of Taguchi and RSM was validated by conducting validation experiment to ensure that it can work accurately as a prediction tool.

A Study of the Surface Integrity of Titanium Alloy Ti-6Al-4V in the Abrasive Water Jet Machining Process

The abrasive water jet (AWJ) cutting technique is one the most rapidly improving technological methods of cutting materials. In this cutting technique, a thin, high velocity water jet accelerates abrasive particles that are directed through an abrasive water jet nozzle at the material to be cut.