对某发电厂运行0 h, 6万h和11.5万h后的高温再热器T91钢管进行冲击试验, 测定了运行11.5万h后T91钢的韧脆转变温度;并结合断口特征和冲击性能研究了T91钢高温长时运行后韧性的变化规律。结果表明: T91钢运行11.5万h后的韧脆转变温度(FATT50) 为-40 ℃;高温长时运行后, T91钢管的解理断面率增大, 裂纹扩展能降低, 但仍具有优良的塑韧性;在相同的冲击温度下, 运行6万h和11.5万h后T91钢管的裂纹扩展能接近, 这与其组织老化及位错强化有关。

Imapact tests were performed after T91 steel tube high temperature reheater serving for 0 h, 60 000 h and 115 000 h, and then the ductile-brittle transition temperature was determined. The toughness variation of T91 steel after long-time serviing was studied by combining fracture and impact characteristics. The results show that the ductile-brittle transition temperature of the T91 steel was -40 ℃ after it serving for 115 000 h. The T91 steels tube still owned good plasticity and ductility after service for a long time at high temperatre, although their cleavage fracture rate increasing and its crack propagation decreasing. After T91 steels serving for 60 000, 115 000 h, their crack propagation energy had no larger difference at the same impact tempact temperature, which was associated with microstructure ageing disiocation strengthening.