Ferritic stainless steel and ferritic stainless steel pipe with improved mechanical properties of welding portion
A ferritic stainless steel with improved mechanical properties of weld zone is disclosed. The ferritic stainless steel includes, in percent (%) by weight of the entire composition, C: 0.005 to 0.02%, N: 0.005 to 0.02%, Cr: 11.0 to 13.0%, Ti: 0.16 to 0.3%, Nb: 0.1 to 0.3%, Al: 0.005 to 0.05%, the remainder of iron (Fe) and other inevitable impurities, and the ferritic stainless steel has a texture maximum strength of 30 or less in the {001} direction after welding.
1. A ferritic stainless steel comprising, in percent (%) by weight of the entire composition, C: 0.005 to 0.02%, N: 0.005 to 0.02%, Cr: 11.0 to 13.0%, Ti: 0.16 to 0.3%, Nb: 0.1 to 0.3%, Al: 0.005 to 0.05%, Mo: 0.005% or less, B: 0.005% or less, the remainder of iron (Fe) and other inevitable impurities, and
the ferritic stainless steel has a texture maximum strength of 30 or less in the {001} direction after welding,
wherein the ferritic stainless steel comprises a secondary phase present in the weld zone of 10 to 100 pieces/mm 2 after welding, and
wherein the secondary phase comprises nitride, oxide and Laves phase precipitates.
2. The ferritic stainless steel according to claim 1 , further comprising: at least one of Ni: 1.0% or less, and Cu: 1.0% or less.
3. The ferritic stainless steel according to claim 1 , comprising B: 0.001 to 0.005%.
4. A ferritic stainless steel pipe comprising:
a base material comprising, in percent (%) by weight of the entire composition, C: 0.005 to 0.02%, N: 0.005 to 0.02%, Cr: 11.0 to 13.0%, Ti: 0.16 to 0.3%, Nb: 0.1 to 0.3%, Al: 0.005 to 0.05%, Mo: 0.005% or less, B: 0.005% or less, the remainder of iron (Fe) and other inevitable impurities, and
a weld zone having a texture maximum strength of 30 or less in the {001} direction,
wherein the weld zone comprises a secondary phase of 10 to 100 pieces/mm 2 ,
wherein the secondary phase comprises nitride, oxide and Laves phase precipitates, and
wherein a ductile to brittle transition temperature (DBTT) of the weld zone is −50° C. or less.
5. The ferritic stainless steel pipe according to claim 4 , wherein the base material further comprises at least one of Ni: 1.0% or less, and Cu: 1.0% or less.
6. The ferritic stainless steel pipe according to claim 4 , wherein the weld zone has a texture maximum strength of 14.1 or less in the {001} direction.
7. The ferritic stainless steel pipe according to claim 4 , wherein the weld zone comprises 10 to 46 pieces/mm 2 of the secondary phase.