Q460GJEZ35抗震耐蚀耐火特厚钢板的研发

Research and Development of Anti-Seismic,Corrosion-Resistant and Fire-Resistant Extra Thick Steel Plate for Q460GJEZ35

随着越来越多超高层、大跨度建筑工程的开工建设,对建筑结构用钢高强、长寿命、服役安全性等方面提出了更高的要求,发展460 MPa级抗震耐蚀耐火功能复合化建筑用钢具有广阔的市场应用前景。此钢种具有高强韧性、低屈强比、抗层状撕裂和良好的焊接性等性能特点,又兼备耐火性、耐候性等功能,可实现高层建筑用钢厚度减薄,节约钢材用量,同时在不使用防火涂层的情况下能保证高楼大厦在火灾中具备较长时间的承载能力,可广泛应用于较高耐火耐候等级的超高层建筑、大型厂房等钢结构建筑。通过对460 MPa级抗震耐蚀耐火建筑用钢关键技术的对比分析,采用铁水KR脱硫—转炉冶炼—钢包白渣精炼(LF)+钢包真空脱气(VD)精炼—铜板结晶器水冷钢锭模浇铸—钢锭加热—轧机成型—QLT热处理工艺进行试制。成分设计方面,其核心是耐火与耐蚀的复合微合金化设计兼顾其强化作用、晶粒细化作用、耐腐蚀作用、纳米析出相析出行为。为提高其焊接性能,将碳当量控制在0.55以内,通过Cu、Cr、Ni、Mo元素的合理配比实现其高强韧性、耐火、耐蚀功能复合化,同时为降低成本,将贵重合金元素Mo控制在0.30%以下;钢水冶炼方面通过精料入炉、纯净钢冶炼技术实现钢中超低P、超低S、超低O、高纯净度;原始坯料成型采用改进型铜板结晶器水冷锭模,通过定向凝固技术实现钢锭内部微缺陷化;轧制环节通过硬壳法轧制促进表面硬化以使轧制时轧制力渗透至钢板芯部,在提高内部质量的同时实现显微组织均匀细化;热处理环节通过两相区淬火,实现软硬相合理搭配,降低屈强比、细化晶粒,提高冲击韧性。通过成分设计—转炉冶炼—水冷模浇铸—轧制—离线热处理的工艺设计,开发出460 MPa级抗震耐蚀耐火钢板,其屈服强度控制在500~520 MPa、抗拉强度控制在630~650 MPa、伸长率24%~27%,屈强比0.79~0.81,厚度方向断面收缩率均值70%,600℃保温3 h的屈服强度为339~367 MPa,-40℃纵向冲击功200 J以上,耐大气腐蚀性能指数7.5以上,可生产钢板最大厚度150 mm,最大宽度3800 mm,最大长度120000 mm。

With the construction of more and more super high-rise and large-span building projects,higher requirements are put forward for the high strength,long life and service safety of building structural steel.The development of 460 MPa anti-seismic,corrosion-resistant and fire-resistant composite building steel has broad market application prospects.The steel has the characteristics of high strength and toughness,low yield ratio,lamellar tearing resistance and good weldability,as well as fire resistance and weather resistance.It can reduce the thickness of steel used in high-rise buildings,save the amount of steel,and ensure the long-term bearing capacity of high-rise buildings in fire without using fireproof coating.It can be widely used in super high-rise buildings,large factories and other steel structures with high fire resistance and weather resistance.Based on the comparative analysis of the key technologies of 460 MPa anti-seismic,corrosion-resistant and fire-resistant building steel,the process of hot metal KR desulfurization,converter smelting,LF+VD refining,water cooled ingot mold casting of copper plate mould,ingot reheating,rolling mill forming and QLT heat treatment was used for trial production.In the aspect of composition design,the core is the composite microalloying design of fire resistance and corrosion resistance,taking into account its strengthening function,grain refinement function,corrosion resistance function and nano precipitate precipitation behavior.In order to improve its welding performance,the carbon equivalent is controlled within 0.55,and the composite functions of high strength,toughness,fire resistance and corrosion resistance are realized by reasonable proportion of Cu,Cr,Ni and Mo.At the same time,in order to reduce the cost,the precious alloy element molybdenum is controlled below 0.30%.In the aspect of molten steel smelting,ultra-low P,ultra-low S,ultra-low O and high purity of steel can be achieved through fine material feeding and pure steel smelting technology.The original billet was formed by an improved water-cooled ingot mold with copper plate mold,and the micro defects in the ingot were avoided by directional solidification technology.In the rolling process,the surface hardening is promoted by hard shell rolling,so that the rolling force can penetrate into the center of the steel plate,and the microstructure can be refined uniformly while improving the internal quality.In the heat treatment process,the proper combination of hard and soft phases is achieved by quenching in the two-phase zone,so as to reduce the yield strength ratio,refine the grains and improve the impact toughness.Through the process design of composition design,converter smelting,water cooling mold casting,rolling and off-line heat treatment,460 MPa anti-seismic and anti-corrosion refractory steel plate was developed.Its yield strength is controlled at 500-520 MPa,tensile strength is controlled at 630-650 MPa,elongation is 24%-27%,yield ratio is 0.79-0.81,average reduction of area in thickness direction is 70%,and its yield strength is 339-367 MPa after holding at 600℃for 3 h.The longitudinal impact energy at 40℃is more than 200 J,and the atmospheric corrosion resistance index is more than 7.5.The maximum thickness of steel plate is 150 mm,the maximum width is 3800 mm and the maximum length is 120000 mm.