Cause Analysis on Disqualification of Flaw Detection for Q355NE Wind Power Steel
The locations of disqualification of flaw detection for defects are accurately positioned through manual flaw detection of Q355NE plates with disqualification of online flaw detection as well as the microstructure and defects of the lo-cations of disqualification of flaw detection are analyzed with optical microscope and electron microscope. The results showed that the defect corresponding to disqualification of flaw detection for Q355NE wind power steel was the microcrack in the center of steel plate,microstructure of the microcrack area in the center was martensite and bainite with poorer plastici-ty,which was caused by segregation of C and Mn. At the same time,MnS inclusions with long strip shape as well as com-pound of titanium and niobium distributed in chain are found at the crack. The interfacial bonding energy of them and ma-trix is low,continuity of matrix is destroyed so that cracks are easily initiated with the effects of stress. The microcracks in the center are avoided and qualification rate of flaw detection for wind power steel is increased by improving the segregation during solidification process of casting blank and adopting the mode of offline slow cooling of steel plate.
wind power steelultrasonic flaw detectioncenter segregationcrack
万方数据
维普
