铌-钛微合金化中碳硼钢连铸坯的高温力学性能

为了避免或减少铌-钛微合金化中碳硼钢320mm×280mm铸坯(%/:0.35C,0.04Si,0.87Mn,0.010P,0.007S,0.27Cr,0.031Alt,0.03Nb,0.030Ti,0.0018B,0.0046N)表面裂纹,研究了该钢种连铸坯的高温力学性能,并对高温拉伸断口和断口附近显微组织进行了观察。结果表明:在600～1250℃,试验钢在600℃时的断面收缩率为54.4%,其它测试温度点的断面收缩率均高于60%;试验钢第Ⅰ脆性区; 1200℃,第Ⅲ脆性区在750～850℃,在850～1200℃试验钢具有良好的热塑性;试验钢在800℃时具有相对偏低塑性,但拉伸断口微观下仍以韧窝形貌为主;试验钢在实际连铸生产时,采用≤1.0m/min铸速和≥950℃矫直温度,连铸坯表面质量良好。

High Temperature Mechanical Property of Casting Bloom of Nb-Ti Microalloying Medium-Carbon-Boron Steel

In order to avoid or reduce the surface cracks of 320 mm X 280 mm casting bloom of Nb-Ti microalloying of medium-carbon-boron steel(%/:0.35C,0.04Si,0.87Mn,0.010P,0.007S,0.27Cr,0.031Alt,0.03Nb,0.030Ti,0.0018B,0.0046N) ,the high temperature mechanical properties of the bloom are studied,and the microstructure near tensile fracture and impact fracture is observed. The results show that in the range of 600 to 1250℃, the reduction of area of the test steel at 600 °C is 54.4% ,and the that at other test temperature points is higher than 60 %. The I brittle zone of the test steel is higher than 1200℃ and HI brittle zone is 750 ~ 850 °C , and at 850 ~ 1200 °C the tested steel has better hot plasticity. The plasticity of tested steel is relatively low at 800 °C , but the tensile fracture is still dominated by dimpled morphology. The surface quality of continuous casting bloom is good in actual continuous casting production with casting speed ≤1.0 m/min and straightening temperature at 950℃