Austenitic stainless steel welded joint and austenitic stainless steel welding material

Abstract

An austenitic stainless steel welded joint, which comprises by mass %, C: 0.05 to 0.25%, Si: not more than 2%, Mn: 0.01 to 3%, P: 0.05 to 0.5%, S: not more than 0.03%, Cr: 15 to 30%, Ni: 6 to 55%, sol. Al: 0.001 to 0.1% and N: not more than 0.03%, with the balance being Fe and impurities, and satisfies the formula of (Cr+1.5×Si+2×P)/(Ni+0.31×Mn+22×C+14.2×N+5×P)≧1.388, has high creep strength, and moreover, is economical and excellent in weldability. Therefore, the said austenitic stainless steel welded joint can be widely applied as steel pipes, steel plates and so on in such fields where not only high-temperature strength and corrosion resistance but also weldability is required. Each element symbol in the above formula represents the content by mass percent of the element concerned.

1 . An austenitic stainless steel welded joint, which comprises by mass percent, C: 0.05 to 0.25%, Si: not more than 2%, Mn: 0.01 to 3%, P: 0.05 to 0.5%, S: not more than 0.03%, Cr: 15 to 30%, Ni: 6 to 55%, sol. Al: 0.001 to 0.1% and N: not more than 0.03%, with the balance being Fe and impurities, and the following formula (1) is satisfied:
   (Cr+1.5×Si+2×P)/(Ni+0.31×Mn+22×C+14.2×N+5×P)≧1.388  Formula (1),   
     wherein each element symbol in the formula (1) represents the content by mass percent of the element concerned. 
   
   
       2 . The austenitic stainless steel welded joint according to  claim 1 , which further contains, by mass percent, at least one element selected from the first to third groups given below in lieu of part of Fe and, further, the following formula (2) is satisfied:
   (Cr+1.5×Si+2×Nb+Ti+2×P)/(Ni+0.31×Mn+22×C+14.2×N+Cu+5×P)≧1.388  Formula (2),   
     wherein each element symbol in the formula (2) represents the content by mass percent of the element concerned:
 First group: Nd: not more than 0.5%; 
 Second group: one or more of Cu: not more than 3%, Mo: not more than 5% and W: not more than 10% provided that Mo+(W/2): not more than 5%, B: not more than 0.03%, V: not more than 1.5%, Nb: not more than 1.5%, Ti: not more than 2%, Ta: not more than 8%, Zr: not more than 1%, Hf: not more than 1% and Co: not more than 5%; and 
 Third group: one or both of Ca: not more than 0.05% and Mg: not more than 0.05%. 
 
   
   
       3 . An austenitic stainless steel welding material, which comprises by mass percent, C: 0.05 to 0.25%, Si: not more than 2%, Mn: 0.01 to 3%, P: 0.05 to 0.5%, S: not more than 0.03%, Cr: 15 to 30%, Ni: 6 to 55%, sol. Al: 0.001 to 0.1% and N: not more than 0.03%, with the balance being Fe and impurities, and the following formula (1) is satisfied:
   (Cr+1.5×Si+2×P)/(Ni+0.31×Mn+22×C+14.2×N+5×P)≧1.388  Formula (1),   
     wherein each element symbol in the formula (1) represents the content by mass percent of the element concerned. 
   
   
       4 . The austenitic stainless steel welding material according to  claim 3 , which further contains, by mass percent, at least one element selected from the first to third groups given below in lieu of part of Fe and, further, the following formula (2) is satisfied:
   (Cr+1.5×Si+2×Nb+Ti+2×P)/(Ni+0.31×Mn+22×C+14.2×N+Cu+5×P)≧1.388  Formula (2),   
     wherein each element symbol in the formula (2) represents the content by mass percent of the element concerned:
 First group: Nd: not more than 0.5%; 
 Second group: one or more of Cu: not more than 3%, Mo: not more than 5% and W: not more than 10% provided that Mo+(W/2): not more than 5%, B: not more than 0.03%, V: not more than 1.5%, Nb: not more than 1.5%, Ti: not more than 2%, Ta: not more than 8%, Zr: not more than 1%, Hf: not more than 1% and Co: not more than 5%; and 
 Third group: one or both of Ca: not more than 0.05% and Mg: not more than 0.05%.