固定式海洋平台用大厚度D36(Z35)钢板开发

DEVELOPMENT OF LARGE-THICKNESS D36(Z35) STEEL PLATE USED FOR FIXED OFFSHORE PLATFORM

针对固定式海洋平台导管架桩腿用厚钢板低Ceq和低Pcm成分要求、碳偏析控制、附加条件的ASTM A578探伤要求以及表面不允许焊补和修磨面积不超过10%的质量要求,设计低C,Nb、V微合金化成分,90 mm以上特厚板采用钢锭开坯二次成材,90 mm以下钢板连铸成材,控制结晶器液面波动、选用高碱度、较高粘度保护渣、二冷适当弱冷、连铸坯清理、加热、轧制工序控制铁皮,保证了钢板表面质量,良好的精炼及加热、轧制工艺控制,满足钢板探伤要求,控轧组织准备配合适当的正火工艺,钢板主体为细小均匀的珠光体+铁素体组织,保证了钢板强度适中、塑性、韧性、Z向断面收缩率有较大的富余量,最终钢板质量满足了使用要求。

For the demands for thick steel plate used for piles of jacket of fixed offshore platform： low Ceq and Pcm in composition, control of carbon segregation, ASTMA578 flaw detection with additional condi- tions, welding repair not allowed on surface of plate and coped area not being over 10 percent, it is devel- oped the large - thickness steel plate D36 （Z35） with the following technological measures： microalloying composition of C, Nb and V in design, ingot breakdown plus secondary rolling adopted in rolling of super thick plate of over 90 mm and continuous casting adopted in below 90 mm ; controlling mold liquid level fluc- tuation, selecting high - basicity and higher - viscosity mold powder, adopting proper weak cold in secondary cooling, cleaning the continuous casting billet, controlling scale in heating and rolling stage and so to guaran- tee the surface quality of steel plate; excellent refining and heating and rolling processes control to guarantee the demand for flaw detection; organization and preparation for controlled rolling coordinated with suitable normalizing process to make the main body of steel plate as fine and uniform structure of perlite plus ferrite to guarantee the intensity of plate being moderate and plasticity, toughness and Z - direction section shrinkage having large amount of surplus. Overall the steel plate meets user requirements.