علي توكلي مهر

In the Wire Arc Additive Manufacturing (WAAM) method, it is possible to produce large parts with complex geometry, reduce waste material, and lower production costs. This study investigates some of the key parameters affecting the mechanical properties of ER308LSi steel wire used in additive manufacturing. The aim of this research was to optimize the parameters for constructing steel walls, including voltage, wire feed speed, current, layer geometry, and an interpass temperature of 250°C, to determine the appropriate heat input for production and bonding between layers. In total, five walls were constructed with different parameters to achieve an optimized sample, and an additional sample was produced with the same optimized parameters but containing TiN inoculants to refine the columnar grains and improve the microstructure and mechanical properties.In this study, phase analysis was first performed using XRD, and then the microstructure of the samples was analyzed using optical microscopy and scanning electron microscopy (SEM). Additionally, the mechanical properties of the samples were eva‎luated through tensile testing, microhardness testing, and fracture surface analysis. The results showed that with a decrease in heat input, the solidification rate increased, leading to finer columnar grain structures. To reduce heat input, variables such as voltage, current, and wire feed speed were examined. It was observed that in hardness tests, the hardness of all samples decreased from bottom to top, and in tensile tests, it was found that all samples experienced ductile fracture with tensile strength exceeding 600 MPa. The optimized sample was selected with parameters including a voltage of 21.5V, an average current of 126A, a shielding gas flow rate of 15 liters per minute, and a wire feed speed of 5 mm per minute. Moreover, the sample containing the inoculant showed that the grain size became finer from the bottom to the middle of the part, but from the middle to the top, the inoculation effect diminished, resulting in an anisotropic structure. In the area where the inoculant was effective, the grain structure was finer, and the columnar dendrites were broken.

حرارت ورودي , جوانه زايي

heat input , germination

ali tavakoli mehr

Dr. hossein razavi