Stainless steel sheet for exhaust system part use excellent in intermittent oxidation characteristic and exhaust system part

Abstract

A stainless steel sheet free of surface flaws, having an enhanced high temperature strength and corrosion resistance, not becoming brittle at a high temperature, and further exhibiting a high oxidation resistance enabling it to be suitably used as an inside pipe of a double pipe of an exhaust manifold, a turbocharger part, and other automobile exhaust system parts, which stainless steel sheet has a predetermined composition of chemical components and satisfies Cr+20Mo≧24.0%, and Si+20C+15N≧5.8%. Further, an automobile exhaust system part, excellent in both the oxidation resistances of the base material and weld zone using the above stainless steel sheet, having a gradient of change of sheet thickness between the weld metal and the base material of the above stainless steel sheet of 15 degrees or less.

1 . A stainless steel sheet for exhaust system part use excellent in intermittent oxidation characteristic comprising, by mass %,
 C: 0.05 to 0.15%,   Si: 1.0% to 4.0%,   Mn: 0.5 to 3.5%,   P: 0.010 to 0.040%,   S: 0.0001 to 0.010%,   Cr: 20 to 30%,   Ni: 8 to 25%,   Mo: 0.01 to 1.5%,   Al: 0.001 to 0.10%, and   N: 0.13 to 0.50%,   having a balance of Fe and unavoidable impurities, and   having contents of Cr, Mo, Si, C, and N satisfying
   Cr+20Mo≧24.0% and
 
   Si+20C+15N≧5.8%.
 
   
     
     
         2 . The stainless steel sheet for exhaust system part use excellent in intermittent oxidation characteristic according to  claim 1 , further comprising, by mass %, one or more of
 Cu: 0.1 to 3.0%,   V: 0.03 to 0.5%,   Ti: 0.001 to 0.3%,   Nb: 0.001 to 0.3%,   B: 0.0001 to 0.0050%, and   Ca: 0.001 to 0.010%.   
     
     
         3 . The stainless steel sheet for exhaust system part use excellent in intermittent oxidation characteristic according to  claim 1 , further comprising, by mass %, one or more of
 W: 0.01 to 3.00%,   Zr: 0.05 to 0.30%,   Sn: 0.01 to 0.10%,   Co: 0.01 to 0.30%, and   Mg: 0.0002% to 0.010%.   
     
     
         4 . An exhaust system part having a welded structure using a stainless steel sheet according to  claim 1  as a base material and having a gradient of change of sheet thickness at a weld zone of 15 degrees or less. 
     
     
         5 . The stainless steel sheet for exhaust system part use excellent in intermittent oxidation characteristic according to  claim 2 , further comprising, by mass %, one or more of
 W: 0.01 to 3.00%,   Zr: 0.05 to 0.30%,   Sn: 0.01 to 0.10%,   Co: 0.01 to 0.30%, and   Mg: 0.0002% to 0.010%.   
     
     
         6 . An exhaust system part having a welded structure using a stainless steel sheet according to  claim 2  as a base material and having a gradient of change of sheet thickness at a weld zone of 15 degrees or less. 
     
     
         7 . An exhaust system part having a welded structure using a stainless steel sheet according to  claim 3  as a base material and having a gradient of change of sheet thickness at a weld zone of 15 degrees or less. 
     
     
         8 . An exhaust system part having a welded structure using a stainless steel sheet according to  claim 5  as a base material and having a gradient of change of sheet thickness at a weld zone of 15 degrees or less.