Development of Steel Surface Melting Technology for Improvement of Hot Shortness Caused by Tramp Elements

Tramp elements such as Cu cause a severe hot shortness. However, Cu is the useful alloying element for increasing hardness and improvement of the steel properties and Cu is often added to the steels. Therefore, by means of a steel surface melting technology, hot shortness should be suppressed by the addition of Ni only in the surface layer. After hotrolled, the sheets are sandblasted and checked for surface defects due to hot shortness. There are no defects and steel samples alloyed in the surface layer are very clean. Consequently, steel containing Cu alloyed Ni in the surface layer does not indicate hot shortness at the surface.