Yoshikazu Seino

Descaling Behavior of Type430 Hot-Rolled Stainless Steel Coil

Iron oxides can be reduced in a scale by batch annealing treatment in a reducing atmosphere of 7 vol% H2+93 vol% N2 at 1123 K for hot-rolled coils of type430 stainless steel. The heating processes cause cracks, a Cr2O3 layer in the scale and a Cr depleted layer on the substrate. It is possible to produce a large number of cracks in the scale by employing a scale breaker. The ease of descaling is positively related to the amount of bending elongation. Similarly with shot blasting, descaling becomes easier as the projection energy of the shot blasting increases. The pickling solution penetrates the scale through cracks on the surface of the strip, and its acid dissolves the stainless steel coil and part of the scale. The scale peels from the stainless steel coil in island-like exfoliation until the scale has been removed from the entire surface of the stainless steel coil.