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转浆式水轮机大叶片截面差悬殊,0Cr13Ni4Mo钢的导热系数小、膨胀系数大,加热冷却时应力大,因此,在制定热处理工艺时应着重考虑避免产生裂纹和防止变形。我们采取了一次软化退火,正火及两次回火的工艺,其依据如下: 1.不采取高温扩散退火:高温扩散退火虽能减少铸件的枝晶偏析,但不能减少宏观偏析;高温扩氢效果也不明显;高温扩散退火其保温时间一般比锻件淬火或正火的保温时间要长,这就会延长生产周期。 2.不采用中温去氢工艺:铸件一般不会产生白点(除极特殊情况)。铸件不象锻件
Turbid turbine blade section difference between the great, 0Cr13Ni4Mo steel thermal conductivity, expansion coefficient, heating and cooling stress, therefore, in the development of heat treatment process should focus on avoiding cracks and prevent deformation. We have taken a softening annealing, normalizing and twice tempering process, which is based on the following: 1. Do not take high-temperature diffusion annealing: high-temperature diffusion annealing can reduce the dendritic segregation of castings, but can not reduce macro-segregation; Nor obvious; high-temperature diffusion annealing its holding time is generally longer than forging quenching or normalizing the holding time, which will extend the production cycle. 2. Do not use the temperature to the hydrogen process: castings generally do not have white spots (except for very special circumstances). Castings are not like forgings