Study On The Crack Of Plate

The cracks of plates are the familiar quality defects. They hold a majority of proportion of the defects and reduce the receives rate and affect the quality of the plates.Haven widely referred relative literature, the author studied the questions of cracks of plates according to his working experience in WISCO technology department and WISCO'S study fruits. The forming and development of cracks are the mutual results of material's inner microstructure and loaded stress. Therefore, the forming mechanisms of cracks are analyzed firstly from four aspects in this thesis. They are the forming of inner crack during the solidification of slab, high-temperature brittleness of slab, metal organization condition and mechanical behavior during the forming of crack. According to the appearance and forming mechanism, the cracks are classified into longitudinal crack, transverse crack, star crack, marginal longitudinal crack, chap, turtle crack, hair crack and inner crack. And the forming reasons of cracks are discussed primarily in this thesis. In view of longitudinal crack, transverse crack, star crack, marginal longitudinal crack and inner crack are the main types of cracks and they affect the using capability of plates seriously, the five types of cracks are analyzed emphatically in this thesis.The part of experiment in this thesis consists of three partial experiments. Firstly, high-temperature brittleness of steel has been studied through the high-temperature brittleness experiments of steel Q345C-hq, steel Q345C and steel 45#. Then the question of marginal longitudinal crack (or overlap) has been analyzed through the experiment done in WISCO. Finally, metallographic study is done for the crack. And then the conclusions of this thesis have been drawn.