Testing and analysis of metallographic structure of sampled pipe caps
Three samples were taken, two of which had fractures. The cross-sections of the samples were pre-ground, finely ground, ground and polished with water sandpaper and metallographic sandpaper, and etched with a 4% nitric acid alcohol solution to prepare a metallographic test. Using a metallographic microscope to observe the metallographic structure of the sample, it can be seen from the metallographic structure picture near the fracture of the pipe cap with a magnification of 100 times (Figure 5) that no secondary cracks were found in the metallographic structure near the fracture, but there were a lot of secondary cracks near the cracking fracture caused by corrosion, which excluded the possibility of the cracking of the pipe cap caused by stress corrosion. From the metallographic structural picture of the pipe cap with a microscopically magnification of 500 times(see Figure 6), it can be seen that the metallographic structure of the pipe cap was not very coarse; the grain size rating was level 7, and the metallographic structure consists of a lot of ferrites plus a small amount of pearlite. A small amount of bainite structure is also found in the partial pearlite region.https://www.landeepipefitting.com/