An investigation on microstructure evolution and mechanical properties of cryogenic steel rebars under different cooling conditions

Effect of Controlling Nb Content and Cooling Rate on the Microstructure, Precipitation Phases, and Mechanical Properties of Rebar

“…The specimens were heated on a Gleeble-3800 (Data Sciences International, Albany, NY, USA) thermal simulator at 20 °C•s −1 to 1200 °C for 5 min. According to the solid solubility theory, when the holding temperature is 1200 °C, the austenite is homogenized and the microalloying elements can be sufficiently dissolved [13][14][15][16]. Second, it was cooled to 900 °C at 10 °C•s −1 for 5 s and then cooled at different cooling rates (1 °C•s −1 , 1.5 °C•s −1 , 2 °C•s −1 , 2.5 °C•s −1 , and 3 °C•s −1 ) to record the thermal expansion curves.…”

“…Air cooling is the most common cooling method that can inhibit the formation of bainite and increase the content of pearlite [15]. Pan et al [16] showed that the microstructure of rebar consists of ferrite, pearlite, and bainite when the cooling rate is less than 5 • C•s −1 , and the microstructure changes to martensite and bainite when the cooling rate is 20 • C•s −1 . Olasolo et al [17] showed that when the transformation temperature was 600-650 • C, the content of ferrite and pearlite in the steel was the largest, and the hardness reached the peak.…”

Effect of Annealing Process on Microstructure, Texture, and Mechanical Properties of a Fe-Si-Cr-Mo-C Deep Drawing Dual-Phase Steel

“…As discussed later, texture can induce plastic anisotropy and influence the formability of a metallic material. Mn can improve not only the stability of austenite but also strengthen ferrite by solution-hardening as well as retard ferrite formation [40,41]. Mo and Cr could be used to partially replace C and Mn for sufficient hardening ability, since they help retard the formation of pearlite or bainite and thus keep a sufficient amount of martensite as well as help enhance the solute-hardening effect.…”