本发明属低合金钢制造领域，具体提供一种屈服强度≥690MPa的焊接结构用耐火耐候钢及其生产方法。其组分及重量百分含量为：C：0 .027～0 .0 8 6％ ，S i ：0 .0 3～0 .1 2％ ，M n ：1 .6 5～2 .12％，P≤0 .003％，S≤0 .002％，Mo：0 .21～0 .40％，Cr：0 .12～0 .25％，Cu：0 .12～0 .28％，Ni：0 .21～0 .43％，Nb：0 .052～0 .095％，V：0 .078～0 .122％，Ti：0 .007～0 .018％，Zr：0 .0023～0 .0072％，Ta：0 .010～0 .025％，[ N ]：0 .0012～0 .0047％，[O ]：0 .0034～0 .0052％，其余为Fe及不可避免的杂质，同时满足：①( 2Zr+Ta )/[O ]＝5 .28～6 .31，②7C+3Mn＝5 .32～6 .67％，③Pcm＝C+Si/30+( Mn+Cr+Cu )/20+Ni/60+Mo/15+V/10+5B≤0 .22％ ；其生产方法生产的产品具有高强韧性，优异的耐火性能、耐候性能( 明显优于CortenB钢)以及抗层状撕裂性能。

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 followiThe invention belongs to the field of low-alloy steel manufacturing, and specifically provides a fire-resistant and weather-resistant steel for welded structures with a yield strength ≥690 MPa and a production method thereof. Its components and percentages by weight are: C: 0.027～0.086%, Si: 0.03～0.12%, M n: 1.65～2.12%, P≤0.003%, S≤0.002%, Mo: 0.21～0.40%, Cr: 0.12～0.25%, Cu: 0.12～0.28%, Ni:0 .21～0.43%, Nb: 0.052～0.095%, V: 0.078～0.122%, Ti: 0.007～0.018%, Zr: 0.0023～0.0072 %, Ta: 0.010～0.025%, [N ]: 0.0012～0.0047%, [O ]: 0.0034～0.0052%, the rest is Fe and unavoidable impurities, while satisfying ：①( 2Zr+Ta )/[O ]=5.28～6.31,②7C+3Mn=5.32～6.67%,③Pcm＝C+Si/30+( Mn+Cr+Cu )/20 +Ni/60+Mo/15+V/10+5B≤0.22%; the product produced by its production method has high strength and toughness, excellent fire resistance, weather resistance (significantly better than CortenB steel) and anti-lamellar tearing performance.