No abstract

Maraging 300 belongs to a family of metallic materials with extremely high mechanical strength and good toughness. Some works have been published about aging temperatures that improve ultimate strength resistance with acceptable toughness levels in this steel family, where the prior austenite grain size obtained by different solution annealing temperature influence in the final mechanical properties. Solution annealing temperatures ranging from 860 °C to 1150 ºC and were kept constant until the aging temperature. These treatments were used in order to investigate their influence on the microstructure and mechanical properties of maraging steel 300, especially with regard to toughness. The characterization of the microstructure was performed by optical microscopy, scanning electron microscope (SEM) and X-ray diffraction (XRD). Mechanical properties were evaluated by Rockwell C hardness and Charpy impact tests. The results showed that there is a temperature range where one can get some improvement in toughness without a large loss of mechanical strength.

ResumoO objetivo deste trabalho é investigar o efeito da pulsação de corrente sobre a microestrutura da zona fundida de soldas dissimilares entre o aço inoxidável ferrítico AISI 444 e o austenítico AISI 316L. Chapas dos referidos aços foram unidas pelo processo de soldagem TIG. As soldagens foram realizadas variando-se a frequência de pulsação de 2 a 8 Hz e sem pulsação, mantendo-se constante a energia de soldagem. A caracterização microestrutural foi realizada por meio de microscopia óptica, MEV, EDS e EBSD. Os resultados mostraram haver um efeito da frequência de pulsação sobre a homogeneidade e microestrutura final da zona fundida. Palavras-chave: Soldagem TIG; Corrente pulsada; Aços inoxidáveis. Abstract The objective of this study is to investigate the effect of pulse current on the microstructure of the fusion zone of dissimilar welds between the AISI 444 ferritic stainless steel and AISI 316L austenitic steel. Thin plates of the respective steels were joint by the TIG process. The welds were made varying the pulse frequency from 2 to 8 and without pulse, maintaining constant the heat input. The characterization of the microstructure was performed using the techniques of optical microscopy, MEV, EDS and EBSD. The results demonstrated that there was an effect of pulsed frequency on homogeneity and final microstructure in the fusion zone.