2008 Volume 26 Issue 2 Pages 137-144
Steel scrap is raw materials of the recycled steels refined in electric arc furnaces, and this recycle process is good for keeping our living environment. Authors focus in the toughness of the recycled steels that contain much tramp elements and nitrogen. Chemical compositions of specimens are 0.17C-0.20Si-1.15Mn,Cu : 0.08–0.50mass%,Ti : 0.006–0.031mass%. This report contains properties of HAZs (heat affected zones) in thermal cycled mother steels, and these HAZs were estimated a heat input of 45-600 kJ/cm. The following experimental results are obtained. TiN particles fasten on γ grain boundaries, and improve the toughness of HAZs. A grain boundary ferrite is restrained by Cu, and ferrite grains become fine, too.