高炉炉壳用超宽BB503Z35厚板的生产实践

目前采用铸坯生产的厚度100 mm以下、宽度不大于3 500 mm、探伤保Ⅱ级的高炉炉壳用BB503Z35钢板,已满足不了大容量高炉的使用要求。为此,南阳汉冶特钢有限公司采用模铸钢锭对100~120 mm厚、3 800 mm超宽且保Ⅰ级探伤高炉炉壳用BB503Z35钢板进行了开发试制。介绍了BB503Z35钢板化学成分设计,VD炉真空冶炼、水冷模浇注、控轧控冷工艺,研究了正火+控制冷却钢板、高温正火+控制冷却钢板不同热处理下钢板的组织性能。结果表明:通过采用Nb、V、Ti复合微合金化、钢坯低温加热、控轧控冷、高温正火+控制冷却热处理工艺,成功研发出100～120 mm厚、3 800 mm超宽BB503Z35钢板。钢板碳当量为0.405%,焊接裂纹敏感性指数Pcm为0.228%;钢板中夹杂物及夹杂物总量均较低,内部组织均匀、晶粒度细小、带状组织轻微,各项性能指标有较大富裕;超声波探伤检验符合NB/T 47013.3—2015 标准Ⅰ级要求;在高温930 ℃时钢板高温塑性较好,面缩率指标优异,符合高炉炉壳用钢的耐高温性能要求。

Production practice of ultra-width BB503Z35 steel heavy plate for blast furnace shell

At present, the BB503Z35 steel plate for blast furnace shell with a thickness of less than 100 mm and a width of not more than 3 500 mm and grade II for flaw detection and protection produced by casting billets cannot meet the requirements of large-capacity blast furnaces.For this reason, BB503Z35 steel plate for blast furnace shell with a thickness of 100-120 mm and ultra-width of 3 800 mm, which is guaranteed to be grade I flaw detection by using die-cast ingots was developed and trial-produced in Nanyang Hanye Special Steel Co., Ltd.The chemical composition design of BB503Z35 steel plate, vacuum smelting in VD furnace, water-cooled mold casting, controlled rolling and controlled cooling process were introduced, and the microstructure and properties of the plates under different heat treatment processes of normalizing+controlled cooling and high temperature normalizing+controlled cooling were studied.The results show that 100-120 mm thickness and 3 800 mm ultra-width BB503Z35 steel plate has been successfully developed through Nb, V, Ti composite microalloying, billet heating at low temperature, using controlled rolling and controlled cooling and high temperature normalizing+controlled cooling heat treatment process.The carbon equivalent of the plate is 0.405%, and the welding crack susceptibility index Pcmis 0.228%.The inclusions and the total amount of inclusions in the plate are low, themicrostructure is uniform, the grain size is small, and the band structure is slight.The performance indexes are relatively rich.Ultrasonic flaw detection of plate meets the requirements of NB/T 47013.3-2015 standard class I.At high temperature of 930 ℃, the plate has good high temperature plasticity and excellent area shrinkage index, which meet the high temperature resistance requirement of blast furnace shell steel.