| 摘要 |
PROBLEM TO BE SOLVED: To provide heat resistant cast steel which has excellent thermal fatigue resistance in addition to heat resistance, and is particularly suitable as a material for parts repeatedly heated to a high temperature of≥900°C such as the exhaust gas manifold and turbohousing of an automobile engine. SOLUTION: The heat resistant cast steel is an alloy composed of by mass, 0.2 to 1.0% C, 8.0 to 45.0% Ni, 15.0 to 30.0% Cr,≤10% W and 0.5 to 3.0% Nb; wherein, [C-0.13Nb]: 0.05 to 0.95%, and the balance Fe with inevitable impurities. In the cast structure, MC type carbides are dispersedly present by an amount in the range of 0.5 to 3 atomic %, and M<SB>23</SB>C<SB>6</SB>type carbides by an amount in the range of 0.5 to 10 atomic %, and the matrix phase consists of an austenitic phase essentially consisting of Fe-Ni-Cr. The steel has a mean thermal expansion coefficient of≤20.0×10<SP>-6</SP>in the temperature range from a room temperature to 1,050°C, and has a tensile strength of≥50 MPa in the temperature range of≤1,050°C. COPYRIGHT: (C)2004,JPO
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