Heat Treatment Process On The Organization And Performance Of 12cr2mowvtib (102 Steel)

12Cr2MoWVTiB (102 steel) is low carbon and dilute-alloy bainitic steel which exhibits good integrated mechanical properties. Its heat resistance is higher than that of the foreign same steel grade and can reach the level of some Cr-Ni austenitic steels at 620℃. Therefore, substituting 102 steel for Cr-Ni austenitic steel that is costly and has many problems in processing and operation will decrease the cost of boiler of power station and processing difficulties and guarantee the safety of operation.The production technology of 102 steel tube was attained as "smelting + horizontal continuous castingâ†'hot rollingâ†'heat treatment" or "smelting + horizontal continuous castingâ†'hot rollingâ†'cold drawingâ†'heat treatment". The microstructures of samples were studied by optical microscopy, scanning electron microscopy, electron probe and transmission electron microscopy. And the mechanical properties were also measured.The effect of normalizing temperature and heating time on the microstructures and properties of 102 steel was analyzed. The result showed that normalizing temperature has an evident influence on the long-time strength, e.g. the long-time strength increases markedly when the normalizing temperature increases from 950℃to 1050℃or even higher. Normalizing time ranging from 35 to 60 min hardly influences the microstructures and mechanical properties of 102 steel, while the cooling velocity has a little effect on them.The effect of tempering temperature and time on the microstructures and properties of 102 steel was also analyzed in this thesis. The result indicated that the strength of 102 steel decreases rapidly and the ductility of it increases when the tempering temperature is higher than 650℃, while the hardness begins to decrease when the tempering temperature reaches 700℃. The strength and hardness decrease slowly and the elongation increases slightly in the tempering temperature range of 750-800℃, and the 102 steel has the best integrated mechanical properties when tempered in this temperature range.Corresponding advices based on the results outlined above were proposed for factory production.