Microstructural analysis of 400 grade maraging steel after thermomechanical treatment

Abstract

Maraging steels 400 were developed targeting to reach high levels of mechanical resistance with a good toughness. Being maraging steels highly alloyed materials, they have the tendency to segregate some elements in its as-cast condition. This micro segregation is reduced when the material is homegeneized at high temperatures for long time. Elements that more segregate are Ti and Mo. Microsegregation was investigated by means of scanning electron microscopy (SEM) with microanalysis by EDS. On the other hand, by means of electrical resistivity it was observed that the more dissolved are the alloying elements the higher is the electrical resistivity. In forging, the resistivity tends to increase and an additional thermal treatment for 835°C strongly reduces the electrical resistivity increasing simultaneously the microhardness. Through transmission electron microscopy (TEM) an intense precipitation was observed. Subsequent thermal treatments to higher temperatures, showed that the ideal solubilization of the maraging steel 400 occurs at 1050°C.