In this study, the effect of the use of foundry sand as a filler on the formation of different layer configurations in polyester/fiber glass composites was investigated. The composites were produced by hand lay-up lamination and their physical, mechanical and morphological properties were investigated. In the samples containing sand as the filler, the configuration of the layers affected the interface region of the phases, thus significantly affecting the mechanical properties of the samples. The morphological analysis of the composites revealed the presence of regions with moderate interaction between the phases (polyester / glass fiber and polyester / foundry sand), which can cause delamination of the layers and consequently the deterioration of the mechanical properties of the composites when compared to the composite without the sand.

With the use of laser welding, it is possible to join different steel, with different thicknesses, with or without the action of protective layers. The quality of laser radiation makes it possible to get certain characteristics that are impossible to get by other processes, such as high welding speeds, less metallurgical effects suffered by the heat-affected zone (ZAC), and this process also does not require filler metal, therefore it is free from possible contamination. Combined with traditional welding methods, laser welding produces narrower weld beads, allowing for better prevention of corrosion and thermal distortions. Although the process already has high industrial knowledge, some random defects, such as porosities and inconsistencies, are still found. This work presents a systematic study to determine the influence of laser welding parameters and how these parameters influence welding defects. For this, the experimental part was carried out in the welding laboratory - LABSOLDA, of the Federal University of Santa Catarina - UFSC, during the laser welding processes, a welding speed of 2.4 m/min was reached. For this experiment, argon was used as a shielding gas and 1020 steel was used as the base material.

Pipelines for oil and gas, manufactured in high-strength low-alloy steels (HSLA), such API pipes, promote high levels of strength and fracture toughness. Therefore, it is important to ensure this high level of toughness in the welded joint. When the pipelines are exposed for many years to wet H2S environments, they can fail due to hydrogen embrittlement. Thus, it is important to evaluate the influence of different weld specifications in the susceptibility to hydrogen embrittlement. In this case, the aim of this work was to study the susceptibility to hydrogen embrittlement of API 5L X52 steel and in the welded region in wet environments. The welding was performed in the circumferential direction by GMAW process in two different specifications (with lower and higher thermal input). The susceptibility to hydrogen embrittlement was carried out according to NACE TM0177 and SSRT (slow strain rate tensile tests) test, performed according to ASTM G 129 standard. All welded joints and base metal did not show any signal of cracks and susceptibility to hydrogen embrittlement, according to the requirements of the NACE TM0177 test. According to SSRT tensile test, the results showed that the welded joints and base metal are susceptible to hydrogen embrittlement. The tensile tests exhibited a drop in the strain and necking, and higher values of yield stress. The welded joint with the lowest heat inputs employed in the welding process presented the highest susceptibility to hydrogen embrittlement.