Rodolfo Rodríguez Baracaldo

OBTENCIÓN DE MATERIALES METÁLICOS DE TAMAÑO DE GRANO ULTRAFINO

The goal of this article is to provide a general overview about Severe Plastic Deformation processes SPD, one of the most important techniques available to obtain industrial amounts of materials with grain size lower than 1µm, called ultrafine UFG. A description of the more important SPD techniques is made, based on fundamental principles, advantages and limitations of each one of them. These techniques are presented considering the remarkable increase of physics and mechanicals properties in comparison with conventional metallic materials. Some potential applications of UFG metallic materials are included.

Efecto de los parámetros de la soldadura a tope por destello sobre las propiedades mecánicas de rines metálicos

The effects of process variables on weld quality are being studied for the Flash Butt Welding of SPFH 590 steel. The resulting welded metal and heat affected zones were characterized by tensile testing, bending testing, Rockwell hardness testing and microstructural analyzed by optical microscopy, and scanning electron microscopy. The results indicated a transformation of the metal joint from ferrite laminar to acicular ferrite. During the welding process, the long-shaped grains grew and became rounded-shaped, and through the cooling process, some side plate Widmanstatten ferrite structure is formed. The significance of process factor levels on microstructure, weld zone strength, and fracture characteristics were analyzed. The welding process parameters, 5V (voltage), 2.3 mm (upset), and 2 s (flashing time), displayed the best properties combination (strength and ductility) of all the test performed.

Effects of the Vacuum Moulding Process on the Mechanical Properties of Cotton/Epoxy Composite

A study on the effect of the vacuum assisted resin transfer moulding (VARTM) manufacturing process on the mechanical properties of cotton/epoxy composite is presented in this investigation. Woven cotton was used as reinforcing material embedded in epoxy resin. The woven cotton was treated with sodium hydroxide for one hour at concentrations of 0% to 20%. The tensile test showed that the untreated material had the highest ultimate strength and Young’s modulus. Observation of the fracture surface by scan electronic microscopy (SEM) was compared to the hand lay-up process as well as the results of the tensile test. The comparison showed that the VARTM process presents better mechanical properties than the hand lay-up process due to the reduction in discontinuities observed by means of optical microscopy.