In this work, Gas Metal Arc Welding (GMAW) was used to study the influence of heat input (i.e. cooling rate) on mechanical/metallurgical properties of square butt welded joints of DP 1000 sheets. The influence of filler metals of different strengths on the mechanical properties of joints was also tested. A significant decrease in hardness was observed in the Heat Affected Zone (HAZ) due to martensite tempering, in regions where peak temperature was close to isotherm AC1 (calculated in 735 o C for these steel); coincidently, fracture in every tensile test occurred in regions where martensite was tempered, even when a wire of less strength was used. It was noticed that the decrease in ultimate tensile and yield strength of base metal was inherent to welding. When minimum heat input was used, deterioration in mechanical properties was less pronounced, once degree of HAZ softening was smaller. Elongation of joints increased with increasing heat input.

Titanium dioxide with high specific surface area in the crystalline anatase phase is a promising material for environmental applications. In this work, TiO2with good applicability for photocatalytic processes has been obtained using the low energy consumption synthesis based on oxidant peroxide method combined with microwave-assisted low temperature hydrothermal treatment. To prepare the material, titanium propoxide, hydrogen peroxide, and isopropyl alcohol were used. The influence of time and temperature during the hydrothermal step on properties like morphology, crystallinity, phase composition, specific surface area, and photocatalytic behavior were investigated. Photoactivity was measured using the methyl orange decomposition method in UV-A light. Increasing temperature during hydrothermal step, photocatalytic properties could be improved. The nanostructured TiO2particles synthesized at 200°C and 30 min with this method showed photocatalytic activity comparable to commercial Aeroxide® TiO2P25.