风电钢Q345D连铸板坯三角区裂纹控制
首发时间:2018-11-27
摘要:针对某钢厂风电钢Q345D连铸板坯三角区裂纹缺陷,运用光学显微镜和扫描电镜分析三角裂纹周围组织与形貌;建立板坯凝固传热模型分析温度场;测量喷嘴横向水量分布分析铸坯冷却均匀性,进而探究三角区裂纹形成机理。研究表明,三角区裂纹附近出现铁元素为主的球状填充物,裂纹两侧晶粒差异较大,三角裂纹缺陷发生在铸坯高温糊状区。三角区裂纹产生于距弯月面2.3m~8.8 m区域, 即二冷2~5区,该区域喷嘴横向水量分布存在明显的波峰波谷现象,易使铸坯横向冷却不均匀,诱发板坯宽面鼓肚,致使三角区裂纹产生。基于此,结合现场工艺,制定了三角区裂纹的控制方案,通过改进喷嘴型号改善板坯冷却均匀性,与调整扇形段0~13段辊缝收缩值抑制鼓肚,有效地将Q345D连铸板坯三角区裂纹从1.48%降低至0.43%。
关键词: 钢铁冶金 连铸板坯 三角区裂纹 辊缝收缩 喷嘴 二次冷却
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Control of triangle-zone cracks for Q345D continuous casting slab of the steel for wind power towersl
Abstract:In view of the triangle-zone cracks of Q345D continuous casting slab in a steel plant, metallographic analysis, scanning electron microscopic energy spectrum analysis, the heat transfer model of slab solidification and the characteristics of measuring the transverse water distribution of nozzle were carried out, and the formation mechanism of triangular crack was studied. The results show that iron-dominated spheroids appear near the triangular crack, and the grain size on both sides of the crack is quite different. The triangle-zone cracks occur in the paste zone of slab at high temperature. The triangle-zone cracks occur in the area 2.3 m~8.8 m away from the meniscus, i.e. 2~5 zone of secondary cooling. There are obvious peaks and valleys in the transverse water distribution of nozzles, which easily leads to slab bulging and triangle-zone cracks. By improving nozzle and adjusting roll gap shrinkage value, the triangle-zone cracks of Q345D slab can be effectively reduced from 1.48% to 0.43%.
Keywords: Ferrous metallurgy Continuous casting slab Triangle-zone cracks Roll gap shrinkage Nozzle;Secondary cooling
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