690合金傳熱管內(nèi)外壁“細晶”組織的成因及控制

Contributing Factors and Control of Formation of Fine-grain Microstructure in Inner and Outer Surfaces of 690 Alloy Tube for Heat Transfer Service

摘要: 分析了冷軋變形量、脫脂質(zhì)量、熱處理保護氣氛、中間品原始組織等對690合金傳熱管光亮固溶熱處理組織的影響。分析認為：內(nèi)外壁再結(jié)晶形核率的差異是導致690合金傳熱管內(nèi)外壁出現(xiàn)異?！凹毦А苯M織的根本原因；通過改變熱處理氣氛、增大冷軋變形量、改善脫脂質(zhì)量等手段，可有效消除光亮固溶熱處理后690合金傳熱管內(nèi)外壁的“細晶”組織。

Abstract: Analyzed are the factors affecting the bright solid solution heat treatment microstructure of the 690 alloy pipe for heat transfer service, including the cold-rolling deformation rate, degreasing quality control, heat-treatment protective atmosphere and original microstructure of the semi-product.The analysis reveals that the difference between the re-crystallization nucleation rate of the inner surface and that of the outer surface acts as the root cause for development of the abnormal fine-grain microstructure on the inner and outer surfaces of the pipe. Accordingly, such fine-grain microstructure of the said 690 alloy pipe as occurred after bright solid solution heat treatment is expected to be eliminated by means of improving the heat treatment atmosphere, increasing the deformation rate and improving degreasing quality, etc.