| The effects of niobium and titanium on the weldability of type 409L ferritic stainless steel were investigated. The stabilization ratio for obtaining a fully ferritic structure in the welds was changed to the variation of stabilized alloying elements(Ti, Ti+Nb) and weld thermal cycles. In order to get a fully ferritic structure at heat affected zone of dual(Ti and Nb) stabilized stainless steel after TIG welding, the stabilization (Ti+0.5Nb)/(C+N) ratio was 5.6 minimum, while the ratio of Ti stabilized stainless steel was 8.3 minimum. The difference of the ratio for both stabilized stainless steels might be due to different stability of carbides(TiC, NbC) at high temperature, The dual(Ti+Nb) stabilized stainless steel had a good intergranular corrosion resistance of the weld at the ratio of 6.5. The larger and rectangular shaped particles formed in the melt were identified as TiN and their size was about 3 to 5㎛. Most fine particles with the size of 0.05∼0.1㎛ were identified as (Nb, Ti)(C, N). The higher Nb content in (Nb, Ti)(C, N) was detected in the composition of the finer particles. |
|
