This standard specifies a microscopic test method for determining the grain size of ferrite or austenite in steel. This standard also stipulates how grain boundaries appear and how to determine the average grain size of a test piece with uniformly distributed grains. Since the shape of a crystal grain is three-dimensional (three-dimensional), the cut plane of a microscopic sample can be any point from the edge of the crystal grain to the part with the maximum diameter. Even if the crystal grains are exactly the same size, the size of the crystal grains that appear on a plane (two-dimensionally) varies within a certain range.
JIS G 0551:2005 history
2022JIS G 0551:2020 Steels -- Micrographic determination of the apparent grain size
2013JIS G 0551:2013 Steels.Micrographic determination of the apparent grain size
2005JIS G 0551:2005 Steels -- Micrographic determination of the apparent grain size
1998JIS G 0552:1998 Methods of ferrite grain determination test for steel
1977JIS G 0551:1977 Methods of austenite grain size test for steel