Factors Influencing the Formation of Flakes in Steel

Flakes also called shatter cracks, chrome checks, fish eyes, snowflakes or hairline cracks are internal fissures, which are found to be the frequent causes of failures in service particularly in heavy engineering parts such as axles, crankshafts, rotors, posts of heavy shears or press-es and many other instances. Due to their very sharp borders these flakes initiate fatigue fractures.An example of this is given in Fig. I which shows the fracture of a large intermediate Sheet Mill shaft broken with a poor service life of only three months. The fracture has ext-ended near the two keyways, but it can be clearly recog-nised that the fracture started away from the keyways and at some of the flakes distributed in the fracture surface as indicated by the arrows