Effects of Gd on Microstructure and Mechanical Properties of Duplex Stainless Steels for Neutron Absorbing

Abstract:

The effects of different Gd contents on microstructure and mechanical properties of 00Cr23Ni8Mo1.4Mn1.4Si0.5 alloy were researched. Results indicate that element Gd exists mainly in three forms in the alloy: Gd₂O₃, M₁₂Gd, and M₃Gd phases (M=Fe, Cr, Ni). With the increase in Gd content, the contents of Gd-containing precipitate and ferrite phase are increased, whereas the austenite phase content is decreased. The Gd oxide and precipitation of two Gd-containing phases are the main causes of cracking in the alloy during the hot deformation process. The partially aggregated Gd oxide particles and the difficult-to-deform Gd-containing precipitates on the grain boundary jointly decrease the hot ductility of the alloy. With the increase in amount of Gd addition, the tensile strength and section shrinkage ratio of the alloy are decreased. Furthermore, M₃Gd is harder and more brittle, compared with M₁₂Gd, resulting in a more detrimental impact on the mechanical properties of alloy.