| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a double structure exhaust manifold hardly generating weld defect and good in high temperature strength of an inner pipe.SOLUTION: A base material part component and a weld part component in an inner pipe contain, by mass%, 0.08% or less of C, 2.0% or less of Mn, 0.04% or less of P, 0.01% or less of S, 17.0 to 20.0% of Cr, 10.0 to 14.0% of Ni and 0.08% or less of N. Also the base material part component contains, by mass%, 1.5 to 4.0% of Si and the weld part component contains 1.0 to 3.0% of Si. Further the balance of the base material part component and the weld part component is Fe with inevitable impurities. An area of 200μm from a bond part to a side of the weld part in the inner pipe is 3.0% or more by a volume percentage of theδferrite amount, the volume percentage of a heterogenous phase is 2.0% or less and 0.2% bearing force of the inner pipe at 1000°C is 30 MPa or more.</p> |
