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.
出处
《北京科技大学学报》
EI
CAS
CSCD
北大核心
2009年第9期1116-1121,共6页
Journal of University of Science and Technology Beijing
关键词
铸坯
冷却速度
先共析铁素体
热塑性
裂纹敏感性
slab
cooling rate
proeutectoid ferrite
hot ductility
cracking susceptibility
