TT处理对690合金传热管显微组织和性能的影响

Effects of Thermal Treatment on Microstructure and Properties of 690 Alloy Heat Transfer Tubes

对核电站蒸汽发生器用690合金传热管进行不同保温时间的特殊热处理,研究保温时间对690合金传热管显微组织、拉伸性能和晶间腐蚀性能的影响。研究结果表明:经10~30 h的特殊热处理后,690合金传热管晶界均分布连续或半连续的碳化物,且晶内分布极少量的碳化物和大量的孪晶;随着保温时间的增加,碳化物有粗化的现象,室温及350℃拉伸性能变化不大,拉伸性能缓慢增加,350℃的抗拉强度仍能保持在600 MPa以上;随着特殊热处理保温时间的增加,690合金传热管晶间腐蚀速率未发生明显变化,且均不超过13 mdd(毫克/平方分米·天)。

The thermal treatments under different holding time were performed on 690 alloy tubes for steam generator in nuclear plant. The effects of thermal treatment on microstmcture, tensile strength and intergranular corrosion property of 690 alloy tubes were studied. The results show that after thermal treatments for holding 10-30 h, continuous and semi-continuous carbides are distributed at grain boundaries and few carbides and lots of twin crystals are distributed in the grains of 690 tubes. When the holding time increases, size of carbides increases slightly, tensile strengths at room temperature and 350℃ change a little, tensile strength increases slowly. Tensile strength can maintain over 600 MPa at 350℃. The intergranular corrosion rate keeps stable and is less than 13 todd with holding time increasing.