Comparative Study on Austenite Decomposition and Cu Precipitation During Continuous Cooling Transformation

Influence of cooling rate on the precipitation behavior in Ti–Nb–Mo microalloyed steels during continuous cooling and relationship to strength

“…However, the majority of carbides predominantly precipitate during continuous cooling after finish rolling in hot-rolled plate that is not subjected to isothermal process in industrial practice. The precipitation strengthening is provided by carbide particles that nucleate in austenite during finish rolling, interphase precipitation during γ/α transformation, and supersaturated precipitation nucleated in ferrite matrix during continuous cooling after finish rolling [10][11][12]. Continuous cooling of pancake-shaped austenite from finish rolling temperature at different cooling rates results in various types of microstructures with different strengths and hardnesses.…”

Dynamic Continuous Cooling Transformation Behavior of A Novel Cu-bearing Pipeline Steel

“…Abe et al 29) reported that the transformation kinetics for austenite to ferrite showed that Cu precipitation occurred only at a certain region of critical cooling rate and temperature in a Cu-bearing high-strength low-alloy (HSLA) steel, which is usually described in terms of interphase precipitation. 24) In order to verify this possibility in the present study, the TEM images of 2.0 Cu steel after cooling at 2°C/s were observed. Just as shown in Fig.…”

“…Much research has been done on the effect of Cu on ferrite transformation behavior and related microstructure, [18][19][20][21][22][23][24] and it has been already made clear that Cu interphase precipitation could occur only at a certain region of critical cooling rate and temperature. 23,24) However, for the novel micro-alloyed Cu-bearing pipeline steel with a small quantity of nickel, chromium, molybdenum and niobium, it is very important to know the effect of Cu addition on the kinetics of austenite decomposition. In this study, therefore, the dynamic continuous cooling transformation (CCT) behavior of three high Cu content pipeline steels was investigated by dilatometry test, optical microscopy observation, transmission electron microscopy observation, and hardness test.…”

“…Luckily, it can be deduced that those spherical particles should be the Curich precipitates according to the chemical compositions of steels (Table 1). 24) believed that the Cu precipitation took place only in association with polygonal ferrite transformation by interphase precipitation mechanism and no Cu precipitates were detected in the acicular ferrite during continuous cooling. This is consistent with the result of present work, as shown in Figs.…”

Regulation of Cu precipitation by intercritical tempering in a HSLA steel

“…4,5 The Cu precipitation characteristics in aspect of compositions, sizes, and morphology depend on the actual cooling rate. 6 The Cu precipitates generally exhibited a constant crystallographic orientation within ferrite grains, and were arranged in rows in association with the ferrite/austenite growth interface. 7 In the case of quench-aging process, Cu precipitation is greatly associated with carbide formation, because the potential crystallographic defects in martensitic structure such as dislocations and low-angle martensite lath boundaries usually act as preferential nucleation sites for the co-precipitation of Cu-rich phases and carbides.…”