soldagem a laser de aços de ultra-alta resistência Laser welding of ultra-high strength steel

The high strength steels low-alloy (HSLA) as the 4340 and 300M, and ultra-high strength steels as maraging steel are as important to the development of industrial and civil construction as for national defense. In Brazilian satellite launch vehicle (SLV) are used steels 300M and 4340 and there are studies to enable the introduction and replacement of HSLA steels for maraging steel. For the application of this material in the automotive, aviation and space industry, it is necessary a greater understanding of the weldability of these steels, correlating with its mechanical properties. In this regard, the parameters were determined by previous studies for welding suitable for these three types of steel with a thickness of up to 3 mm, allowing a comparison of the mechanical properties and microstructural characteristics. In 300M and 4340 steels quenching occurs with increased hardness in the weld region and is observed a decreasing gradient of hardness between the fusion zone (FZ) and the base material (BM), to avoid brittleness is performed a heat treatment of tempering. In the Maraging steel the hardness reduction occurs in the fused zone, an increase in hardness in part of the heat affected zone (HAZ) caused by precipitation process and further reduction of hardness until the hardness of the substrate in regions farthest from the weld, to retrieve the resistance is carried out aging treatment.