AES analysis of fracture toughness variation with heat treatment in an 18 Ni (250 grade) maraging steel

Microstructural evolution in a new 770MPa hot rolled Nb–Ti microalloyed steel

“…In spite of the fine grain size of 3-5 m, excessive grain boundary precipitation of (Fe,Mn) 3 C has an adverse effect on toughness [11], where the effect of grain boundary precipitation is to provide a macroscopically continuous fracture path, while on the microscopic scale the fracture mode may be of mixed mode type, consisting of quasi-cleavage and dimple rupture [11]. This situation is most likely to occur if there is continuous or discontinuous precipitation along the grain boundaries, as observed in Figs.…”

Nano-sized precipitation and properties of a low carbon niobium micro-alloyed bainitic steel

“…Three kinds of precipitates can be observed: Nb and Ti-rich precipitates in size of $30-70 nm, Nb-rich precipitates in size of $ 10-20 nm, and cuboidal Ti-rich precipitates. These cuboidal Tirich precipitates could usually act as nuclei for NbC/Nb(C,N) precipitation [22]. Previous work [23] has suggested that these strain induced precipitations have the strong effect on the prior austenite grain refinement for high strength high toughness steels.…”

Influence of aging temperature on strength and toughness of laser-welded T-250 maraging steel joint

“…It can be seen that there are no carbides or carbosulfides observed in the fractures of the laserwelded T-250 maraging steel. This phenomenon is different from the research [22], because the aging temperatures in this work are lower than the austenitizing temperature at which the carbides or carbosulfides are easy to precipitate. Besides, the carbon content of T-250 maraging steel in this work is lower than that of C-250 maraging steel.…”

“…The low strength and toughness of welded joints are attributed to segregation of elements and the associated formation of titanium carbide and nitride inclusions [20,21]. Especially when the heat-treatment temperature is higher, such as above 820°C, the precipitates of carbides or carbosulfides have a significant influence on the mechanical properties of maraging steel [22,23]. So the changes of microstructures like precipitates and reverted austenite have received considerable attention.…”