Effect of Niobium on the Properties of Welded Joints in the 2.25% Cr-1% Mo Type Steel with Nickel and Niobium Additions

摘要

The effects were studied of the chemical composition of the base material and of welding parameters on the properties of welded joints of steel 08Cr2.25Mo1NiNb for fast reactor steam generators. Welding was done using Boehler-Fox electrodes and electrodes developed in Czechoslovakia. Testing revealed that the welded joint hardened and embrittled depending on the content of free niobium. The occurrence of eutectic formation of a general composition of Nbsub(m)Xsub(n) and possible of the Fe sub 2 Nb phase was considered to be one of the possible unfavourable microstructural factor which affects the mechanical properties of the thermally affected zone. The effect of the cooling rate delta tausub(8/5), ie., the effect of welding technologies was also found to be a function of the free niobium content. The results of welded joint creep to the fracture showed that until the 2x10 exp 4 fracture time no negative effect of the welding cycle on the welded joint refractoriness was found. (Atomindex citation 12:601761)