本发明涉及建筑结构用耐火耐候钢板技术领域，尤其涉及一种690MPa级建筑结构用耐火耐候钢板及其制造方法。钢板由如下重量百分含量的化学元素组成：C：0 .05％～0 .10％，Si：0 .10％～0 .40％，Mn：1 .20％～1 .80％，P≤0 .010％，S≤0 .0 0 3％ 、N i ：0 .7％ ～1 .1％ ，C u ：0 .6 5％ ～1 .1 0％ ，M o ：0 .2 0％～0 .6 0％ ，N b ：0 .0 7％～0 .1 2％ ，V ：0 .0 5％～0 .0 7 5％ ，T i ：0 .0 2％～0 .035％，B≤0 .0025％，Al0 .01％～0 .04％，余量为铁和不可避免的杂质。本发明采用两相区一次热处理工艺，获得了适当比例且稳定的逆转变奥氏体组织，最终获得了由回火态马氏体、纳米析出相，和残余奥氏体组成的复相组织。冶炼、连铸工艺方案实现低磷低碳控制。产品具有高强韧性、高塑性、低屈强比、优异的耐火性能、耐候性。

The invention relates to the technical field of fire-resistant and weather-resistant steel plates for building structures, in particular to a fire-resistant and weather-resistant steel plate for 690 MPa-class building structures and a manufacturing method thereof. The steel plate is composed of chemical elements with the following weight percentages: C: 0.05% to 0.10%, Si: 0.10% to 0.40%, Mn: 1.20% to 1.80%, P≤ 0.010%, S≤0.0 0 3%, Ni: 0.7% ～1.1%, C u: 0.65% ～1.10%, Mo: 0.20% ～0.60%, N b ：0.07％～0.12%, V：0.05%～0.075%, Ti:0.02％～0.035% , B≤0.025%, Al0.01%～0.04%, the balance is iron and unavoidable impurities. The invention adopts the one-time heat treatment process in the two-phase zone to obtain a proper proportion and stable reverse-transformed austenite structure, and finally obtains a complex structure composed of tempered martensite, nano-precipitated phase, and retained austenite. The smelting and continuous casting process plan realizes low-phosphorus and low-carbon control. The product has high strength and toughness, high plasticity, low yield ratio, excellent fire resistance and weather resistance.