水电站座环用S500Q-Z35钢245 mm特厚板的热处理工艺

S500Q-Z35钢（%:0.13C,0.25Si,0.007P,0.001S,0.010Al,0.39Cr,0.92Ni,0.44Mn,0.02Nb,0.01Ti,0.54Ceq）245 mm板由KR脱硫铁水-120 t转炉-LF-VD-42t模铸-轧制-热处理工艺生产。根据控制钢的晶粒长大原理,测定的CCT曲线和临界厚度,以及工艺试验,得出S500Q-Z35钢245 mm特厚板经快速升温至930℃,保温2.0min/mm,快冷至670℃的预淬火,快速升温至880℃,保温2.4 min/mm,循环水+气体搅拌冷至室温的亚温淬火,620~630℃,保温4 min/mm,空冷至400℃压平的回火处理,钢板表面组织为索氏体,其他部位为回火贝氏体+铁素体,具有良好的综合机械性能,钢板Z向性能良好。

Heat Treatment Process of 245 mm Heavy Plate of Steel S500Q-Z35 for Seat Ring of Hydro-Power Station

245 mm plate of steel S500Q-Z35 (/% : 0. 13C, 0. 25Si, 0. 007P, 0. 001S, 0.010Al, 0. 39Cr, 0. 92Ni, 0. 44Mo, 0. 02Nb, 0. 01Ti, 0, 54Ceq) is produced by KR desulphurized hot metal-120 t BOF-LF-VD-42 t ingot castingrolling-heat treatment process. According to principle of control of grain growth, the measuring CCT curves and critical thickness, as well as process test are carried out, it is obtained that with pre-quenching process-rapidly heating to 930 ℃ for 2. 0 min/mm, quickly cooling to 670 °C , the sub-critical quenching-rapidly heating to 880 ℃ for 2. 4 min/mm, with circle water + gas stirring cooling to ambient, and tempering treatment at 620 ~ 630 ℃ for 4 min/mm, air cooling to 400 ℃ and flatting, the surface structure of 245 mm heavy plate of steel S500Q-Z35 is sorbite, the structure in other parts is tempered bainite + ferrite, it has better comprehensive mechanical properties and has better properties of plate Z-direction.