冷却速度对含铌、钛微合金钢铸坯表层组织结构的影响  

Effect of cooling rate on the slab surface microstructure of microalloyed steel containing Nb and Ti

作　　者：马范军[1] 文光华[1] 唐萍[1] 徐国栋[2] 梅峰[2] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]宝山钢铁股份有限公司,上海201900

出　　处：《北京科技大学学报》2009年第9期1116-1121,共6页Journal of University of Science and Technology Beijing

摘　　要：铸坯出结晶器后的冷却速度是影响和决定铸坯表层组织结构(0～5 mm)及第2相析出物分布的关键因素.在开发重熔凝固冷却实验装置的基础上,模拟铸坯在垂直段的凝固冷却条件,研究不同冷却速度对铸坯表层组织与第2相析出物分布的影响.研究表明,在0.8 m.min-1拉速下,以5℃.s-1的冷却速度,使铸坯在出结晶器后表面温度下降到A3温度以下,得到的表层组织均匀,晶界无膜状先共析铁素体,微合金元素析出物在晶内分布均匀,有利于提高铸坯热塑性及降低裂纹敏感性.Cooling rate is a key factor which affects the surface（0 to 5 mm） microstructure of a slab and the distribution of the second phase precipitates after the slab leaves the mould.In order to simulate the thermal cycle when a slab is drawn to the vertical segment,a remelting and solidification cooling experimental device was designed.The influences of cooling rate on the surface microstructure of a slab and the distribution of the second phase precipitates were investigated.It is shown that when the slab is drawninto the vertical segment at a speed of 0.8 m· min^- 1 and the slab surface is cooled to less than the A3 transformation temperature by intensive cooling at a cooling rate of 5 ℃·s^- 1, the surface microstructure of the slab is uniform, the second phase precipitates containing Nb and Ti are well-distributed, and film-like proeutectoid ferrite does not precipitate along the austenite grain boundaries. These help to improve the hot ductility and to alleviate the cracking susceptibility of the slab.

关 键 词：铸坯 冷却速度 先共析铁素体 热塑性 裂纹敏感性 

分 类 号：TF777.1[冶金工程—钢铁冶金]