RESUMO
Mild steel welded products are widely used for their excellent ductility. Tungsten inert gas (TIG) welding is a high-quality, pollution-free welding process suitable for a base part thickness greater than 3 mm. Fabricating mild steel products with an optimized welding process, material properties, and parameters is important to achieve better weld quality and minimum stresses/distortion. This study uses the finite element method to analyze the temperature and thermal stress fields during TIG welding for optimum bead geometry. The bead geometry was optimized using grey relational analysis by considering the flow rate, welding current, and gap distance. The welding current was the most influential factor affecting the performance measures, followed by the gas flow rate. The effect of welding parameters, such as welding voltage, efficiency, and speed on the temperature field and thermal stress were also numerically investigated. The maximum temperature and thermal stress induced in the weld part were 2083.63 °C and 424 MPa, respectively, for the given heat flux of 0.62 × 106 W/m2. Results showed that the temperature increases with the voltage and efficiency of the weld joint but decreases with an increase in welding speed.
RESUMO
Biomedical implant rejection due to micromotion and inflammation around an implant leads to osteolysis and eventually has an implant failure because of poor osseointegration. To enhance osseointegration, the implant surface modification both at the nano and micro-scale levels is preferred to result in an enhanced interface between the body tissue and implant. The present study focuses on the modification of the surface of Titanium (α+ß) ELI medical grade alloy using powder-mixed electric discharge machining (PMEDM). Pulse current, on/off time, and various silicon carbide (SiC) powder concentrations are used as input parameters to comprehend desired surface modifications. Powder concentration is considered as the most important factor to control surface roughness and recast layer depth. A significant decrease in surface fracture density and roughness is observed using a 20 g/l concentration of SiC particles. Elemental mapping analysis has confirmed the migration of Si and the generation of promising surface texture and chemistry. Oxides and carbides enriched surface improved the microhardness of the re-solidified layer from 320 HV to 727 HV. Surface topology reveals nano-porosity (50-200 nm) which enhances osseointegration due to the absorption of proteins especially collagen to the surface.