1995 Volume 81 Issue 10 Pages 1007-1012
Effects of heating conditions on the thickness and composition of the scale, and on the descalability (ease of descaling) of annealed stainless steel were investigated. Cold rolled SUS304 steel strips were continuously heated, soaked and cooled using an experimental annealing line which was equipped with direct fired heating furnaces. Then, specimens from the strips were analyzed by secondary ion mass spectrometry and thin film X-ray diffractometry, and were examined in descaling test. The results obtained are as follows :
Rapid heating of SUS304 steel with impinging flame burners at 6731173K decreases accumulation of Fe and Si oxides into scale, meanwhile soaking at the temperature above 1273K for 1020s accumulates Cr and Mn oxides into the scale. We presume that two annealing conditions above mentioned improve the descalability of SUS304, because oxides of Cr and Mn dissolve rapidly by electrolysis in Na2SO4 solution in descaling process, while oxides of Fe or Si does not dissolve so rapidly or at all. But, too long soaking forms a thicker and Si concentrated scale which makes the time required for descaling longer.
