Abstract：Based on the actual situation ，in order to improve the structure property of T91，be benefit for later processing，the effects of temper temperature within the range of 300- 780 ℃ and cooling rate on the microstructural evolution and hardness change of T91 steel have been analyzed and compared by means of metallographic analysis，scanning electron microscopy and hardness measurement，and to provide some practical reference significance. The results show low degree of tempering to reply at 300- 400 ℃，hardness is difficult to be reduced. Under the condition of tempering at 500- 600 ℃，large amount of fine dispersed granular carbides precipitate in the matrix microstructure of T91 steel，and the Vicker hardness remains high. As the temperature increases at 600- 780 ℃，carbides precipitate along the grain boundary adequately，hardness decreases obviously. With the increase of tempering cooling speed，hardness gradually decreases. A large number of carbides precipitate at the sensitive range from 500 to 600 ℃ under the condition of furnace cooling (5 ℃/min)，and the hardness of T91 steel is high. In the way of tempering at 780 ℃ and cooling rate(50 ℃/min)，getting through the sensitive interval quickly，the carbides precipitate less in the matrix，and the hardness decreases obviously，comprehensive properties meet the processing requirement.
黄贞益，肖亚，侯清宇，王萍，章小峰. 回火温度和冷却方式对T91钢组织性能的影响[J]. 钢铁, 2015, 50(8): 71-76.
HUANG Zhen- yi,XIAO Ya,HOU Qing- yu,WANG Ping,ZHANG Xiao- feng. Effect of temper temperature and cooling rate on the microstructure and properties of T91 alloy steel. Iron and Steel, 2015, 50(8): 71-76.
Thomas Paul V, et al.Microstructural stability of modified 9Cr-1Mo steel during long term exposures at elevated tem-peratures[J].J Nucl Mater, 2008, 378(3):273-
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Thomas Paul V, et al.Microstructural stability of modified 9Cr-1Mo steel during long term exposures at elevated tem-peratures[J].J Nucl Mater, 2008, 378(3):273-
2015, Vol. 50 
