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采用不同的退火温度和淬火工艺、相同的回火工艺对Q390建筑高强钢进行了热处理,并进行了拉伸试验和延迟断裂试验。结果表明:随退火温度从870℃提高到990℃或淬火温度从850℃提高到950℃,建筑高强钢的耐延迟断裂性能先提高后下降;等温退火和分级淬火能更好地提高建筑高强钢的耐延迟断裂性能。与850℃×60 min常规淬火相比,900℃×40 min+400℃×20 min分级淬火的建筑高强钢在0.75倍抗拉强度恒定载荷下的延迟断裂时间延长190%;在0.65倍抗拉强度恒定载荷下的延迟断裂时间延长162%。退火工艺优选为930℃×0.5 h+720℃×1.5 h等温退火,淬火工艺优选为900℃×40 min+400℃×20 min分级淬火。
Using different annealing temperature and quenching process, the same tempering process of Q390 high strength steel was heat treated, and the tensile test and delayed fracture test. The results show that as the annealing temperature increases from 870 ℃ to 990 ℃ or the quenching temperature increases from 850 ℃ to 950 ℃, the delayed fracture resistance of high strength steel firstly increases and then decreases. The isothermal annealing and graded quenching can improve the strength of high strength steel Delayed fracture resistance. Compared with conventional quenching at 850 ℃ for 60 min, the delayed breaking time of high-strength HSS steels quenched at 900 ℃ × 40 min + 400 ℃ × 20 min under constant load of 0.75 times tensile strength was extended by 190%. At 0.65 times tensile strength The delayed fracture time under constant strength load was extended by 162%. Annealing process is preferably 930 ℃ × 0.5h +720 ℃ × 1.5h isothermal annealing, quenching process is preferably 900 ℃ × 40min + 400 ℃ × 20min classification quenching.