冷却工艺对低碳Ti微合金化热轧超高强钢组织性能的影响

Effects of Cooling Parameters on Microstructures and Mechanical Properties of Hot Rolled Ti-Microalloyed Low-Carbon Ultra High-Strength Steels

对实验钢采用低碳高Ti微合金化的成分设计,进行了控轧控冷实验,通过控制不同的冷速和卷取温度,研究了过冷度和原子扩散速率对钢组织演变及(Ti,Mo)C粒子的析出行为的影响.研究结果表明,冷速为30℃/s,卷取温度为420℃时,实验钢屈服强度大于690 MPa,抗拉强度为820 MPa,断后伸长率达18%,并具有良好的低温冲击韧性.显微组织性能研究表明,多边形铁素体、针状铁素体、细小M/A岛及弥散的(Ti,Mo)C析出粒子的混合组织可实现强度和韧性的良好匹配.

The thermo-mechanical control process （TMCP） was carded out for the high Ti microalloyed low carbon steel. The effects of supercooling and the atomic diffusion rate on the evolution of the microstructure and the behavior of the （ Ti, Mo） C particles precipitation were studied under different controlled cooling rates and coiling temperatures. The results showed that the comprehensive mechanical properties of the experimental steel were outstanding with the cooling rate of 30 ℃/s and the coiling temperature of 420 ℃, i. e., the yield strength of the steel was 690 MPa, the tensile strength was 820 MPa, the elongation-after-fracture was 18% , and the experimental steel possessed excellent low temperature impact toughness. The microstructure consisted of polygonal ferrite, acicular ferrite, fine M/A islands and nano-scale （ Ti, Mo ） C precipitates, and the strength and toughness are well-matched.