Performance of SM490YB steel plate under normalizing condition

For SM490YB steel plate, in order to obtain uniform and fine ferrite and pearlite structure and appropriate hardness, in order to obtain the required performance, the continuous cooling rate after normalizing should be controlled at 0.3~1.0℃/s.

For SM490YB steel plate, the normal structure is ferritic + pearlite, As the normalizing temperature increases from 900℃ to 940℃, the yield strength and tensile strength of SM490YB steel sheet decrease from 358 ~367 MPa to 334 ~340MPa, and the tensile strength of SM490YB steel sheet decreases from 509~511 MPa decreases to 490~492MPa, and the effect of holding time on the strength is not obvious. When the normalizing temperature is 900℃, the impact energy absorbed by V-shaped notch at -50℃ is 153~289J, but when the normalizing temperature is 920~940℃, the impact energy absorbed by V-shaped notch at -50℃ is 24~38J low.

By optimizing the composition design and rolling and heat treatment process, using 370 mm thick continuous casting billet to develop 115 mm thick wind power structure SM490YB steel plate with excellent -50℃low temperature impact performance at the core, the process is feasible. The internal quality of SM490YB steel plate reaches the level of NB/T 47013.3-2015 standard Grade 1 inspection, the transverse and longitudinal properties of different positions in the thickness direction meet the design requirements, and the yield strength of the whole plate surplus. 30 MPa, the tensile strength of the whole plate surplus is greater than 15 MPa;  The impact toughness is good at -50℃, and the impact value is between 153 and 315 J.