本发明公开了一种屈服强度450MPa级高耐候热轧H型钢及其热处理工艺。屈服强度450MPa级高耐候热轧H型钢，包括以下化学成分及重量百分比：C：0.06～0.10，Si：0.20～0.40，Mn：0.40～0.70，P：≤0.035，S：≤0.010，Cr：2.00～3.50，Ni：0.30～0.50，Cu：0.30～0.50，V：0.015～0.035，Alt：0.020～0.040，其余为Fe及不可避免的杂质。其热处理回火工艺包括以下步骤：以5℃/s～20℃/s加热至600℃～700℃，保温2h后空冷。据所述热处理工艺得到的高耐候热轧H型钢的屈服强度超过480MPa，抗拉强度超过600MPa，断后伸长率超过20％，‑40℃KV2型冲击功不低于65J，具备良好低温冲击韧性。

The invention discloses 450MPa-grade yield strength high-weather-resistance hot-rolled H-shaped steel and a heat treatment technology thereof. The 450MPa-grade yield strength high-weather-resistance hot-rolled H-shaped steel comprises the following chemical compositions of, by weight, 0.06-0.10% of C, 0.20-0.40% of Si, 0.40-0.70% of Mn, no more than 0.035% of P, no more than 0.010% of S, 2.00-3.50% of Cr, 0.30-0.50% of Ni, 0.30-0.50% of Cu, 0.015-0.035% of V, 0.020-0.040% of Alt, and the balance Fe and unavoidable impurities. The heat treatment tempering technology of the 450MPa-grade yield strength high-weather-resistance hot-rolled H-shaped steel comprises the following steps that heating is conducted to 600-700 DEG C at 5-20 DEG C/s, heat preservation is conducted for two hours, and then air cooling is conducted. The yield strength of the high-weather-resistance hot-rolled H-shaped steel obtained through the heat treatment technology exceeds 480 MPa, the tensile strength exceeds 600MPa, and the percentage elongation after fracture exceeds 20%, -40 DEG C KV<2> type impact work is larger than or equal to 65 J, and the good low-temperature impact toughness is achieved.