Improvement of surface quality of austenitic stainless steel

The cause of scratched defects, occurred at edge area of austenitic stainless cold strip, is identified to be nickel segregation in the surface of continuous cast slabs. The mechanism of segregation occurrence is thought to be as follows. First, disordered oscillation marks in shallow gutters at edge area of slab wide face, induced by narrow face bulging, weakened strength of solidified shell, then cracks in weak solidified shell made segregations. Countermeasures to these problems are as follows. Steep taper of narrow side face in mold makes flat surface of slab wide face, and prevents disorder of oscillation mark. Strong cooling by use of high viscosity continuous casting powder in mold makes solidified shell strong, and depth of oscillation mark becomes shallow. Owing to these methods, segregations in slab surface become to be small, and slabs are transferred to hot rolling mill without surface conditioning by grind. The next subject is to make more shallow depth of oscillation mark by operation of high speed casting.