Cause Analysis of Flat Concave Defects on the Inner Surface at the end of T91 Alloy-Steel Tubes

摘要

The concave defects on the inner surface at the end of T91 alloy-steel tubes were analysed by macroscopic morphology analysis,electron microscope scanning and energy spectrum analysis,metallographic analysis and anion analysis of corrosion products.The composition of water sample and oil sample of finned winding and oil immersion treatment was also analysed.It was found that this kind of defect was not caused by the preservation environment of steel tube,the treatment of finned winding and oil immersion.The defect should be related to the quality of steel tube blank or the processing technology of steel tube.