1Dept. of Metals Engineering, Institute of Materials Science, No.18, Hoang Quoc Viet, Hanoi.
2Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Kusong-do, Yusong-gu, Taejon, 305–701, KOREA.
*Correspondence author E-mail: toduyca@hn.vnn.vn
Effect of addition of RE to Fe-25Cr-6Ni-3Mo-0.25N duplex stainless steel (DSS) on the refinement and globularization of the inclusions to small-smooth sizes are presented. The RE has more positive influence than nitrogen on segregation of impurities in DSS. The grain sizes are reduced after RE addition. The smallest grain size attained is 8.4mm when the RE content is about 0.07%. The REs are ferrite formers leading to the increase of phase amount with increasing RE addition. Nitrogen has negative effect to form δ ferrite, while the REs have positive effect to form δ ferrite. The REs refine nitrides and the carbide amount decreases with increasing RE addition to duplex stainless steel Fe-25Cr-6Ni-3Mo-0.25N.
Duplex stainless steel, rare earth metals, inclusion, delta ferrite, carbides
