---

Inducing compressive residual stress is one of the methods of improving fatigue life in metallic components. There are numerous and various methods for inducing compressive residual stress, such as shot peening and deep rolling. One of the most recent and most advanced methods for inducing compressive residual stress in industrial components is Laser Shock Peening (LSP). LSP is a relatively new and complex process, therefore, vast experimental investigations are needed for better understanding the process. For this purpose in the present work, an Nd: YAG Laser with 1200mJ of energy per pulse was used to investigate the LSP process experimentally on Al 6061- T6 alloy. The effect of process on the hardness beneath the surface, the microstructure, and the surface roughness was studied. In addition, in order to investigate the effect of the LSP process on a notch, a notched sample was treated using the LSP process. The results showed that the process could increase the hardness of the material up to 1000μm below the surface. Furthermore, the results showed that the surface roughness would slightly get increased, while this increase could be limited by properly selecting the process parameters. The LSP process of the notched sample showed that this process could lead to the growth of cracks in such samples.

---

---

---

---

Laser cutting is one of the modern methods for cutting. In this method heat affected zone width and microstructure changes as a result and also sheet deformation are very low in comparison to other thermal methods and a fine cut is the result. The control of heat-affected zone (HAZ) during laser cutting of titanium sheets due to low thermal conductivity and high tendency to chemical reaction is of great importance. In this paper, the effect of some of the most important laser cutting parameters, including the type of assistant inert gas, stand-off distance, cutting speed and power on HAZ width was assessed in CW CO2 laser cutting of Ti-CP sheets, using Taguchi L16 orthogonal array. Metallography of the cut samples, effects of cutting parameters and optimal conditions of cutting were investigated. Taking into consideration the test results, it is suggested to select the highest possible cutting speed for thin Ti-CP sheets and provide the required severance energy by controlling the laser power. The use of helium instead of argon also showed a significant impact on the reduction of HAZ width. Finally, microstructure and hardness changes are presented.

---

Additive manufacturing or 3D printing processes through which applicable complicated parts are directly made based on 3D model of the part has been extensively addressed in numerous research and development tasks for the past years. Certain merits such as decline of time, cost of design and manufacturing of product, processing different engineering materials, manufacturing parts with highly complicated geometries, and manufacturing customized parts should be noted in the case of adopting these methods. Indirect selective laser sintering is one of the interesting methods of integrated manufacturing which could be used for manufacturing of complicated pieces and certain materials such as ceramics with a high melting point and difficult manufacturing process through typical methods. In the present study, indirect SLS of spherical alumina powder particles with a thin layer of amorphous thermoplastic (PMMA and PS). In order to coat alumina particles with different weight percent of thermoplastic, the new method of phase Inversion process was used. Due to significance of geometry and dimensions of the final part, the least probable thickness of thermoplastic was used for manufacturing of parts based on SLS method. In the present study, evaluation of coating and method of coating have been discussed. The evaluative techniques include assessment through scanning electron microscopy, analytical results of Fourier transform infrared spectroscopy and thermogravimetric analysis and differential scanning calorimetry. Finally, green parts where produced based SLS method and through optimal values of laser parameters and selection of alumina powder particles with thinnest thermoplastic coating.

---

---

Selective laser melting is a technology for additive manufacturing where parts are produced by melting a powder bed using a laser beam. Because the metal parts produced by this method can have complex and desired geometries, it is considered a modern method for producing electric motor parts, sensors, and other components. The iron powder used in this study is pure one. The input parameters for this method include laser power, scanning speed, and the hatches distance. The design of the experiments was performed using the Taguchi method. Although many studies have been conducted on the mechanical properties of parts produced by this method, less attention has been paid to magnetic properties. In this research, the effect of selective laser melting parameters on the force of pure iron coercivity was experimentally determined. The optimal levels of parameters for achieving the optimal value of this force were determined using signal-to-noise analysis. The main effects and interactions of the parameters were taken into account in this article. The results indicate that the optimal parameter levels for obtaining the lowest amount of coercive force include a laser power of 220 watts, scanning speed of 400 mm/s, and a hatch distance of 70 micrometers. The hatch distance and scanning speed have the most interactive effects on achieving the lowest amount of coercivity.