Microstructure and mechanical properties of TMCP heavy plate microalloyed steel

Abstract

A microalloyed steel heavy plate was subjected to two-stage controlled rolling and two-stage continuous cooling to explore the microstructure and mechanical properties in the plate. The objective was to obtain superior mechanical properties in the plate by exploiting the advantage of microalloyed precipitates in stimulating intragranular ferrite nucleation. Yield strength, tensile strength, and percentage of elongation of 550MPa, 655MPa, and 26.5% were obtained at quarter-thickness and 515MPa, 645MPa, and 29.5% at mid-thickness. The impact energy determined at −40°C was ~93J and 71J for quarter-thickness and mid-thickness regions, respectively. The microstructure consisted of polygonal ferrite, acicular ferrite, and pearlite. Microalloyed precipitates provided effective nucleation sites for intragranular ferrite and ensured near-homogenous microstructure and mechanical properties in the heavy steel plate.