| 摘要 |
The present invention provides a heat resistant steel for an exhaust valve, containing: more than 0.50% by mass but less than 0.80% by mass of C, more than 0.30% by mass but less than 0.60% by mass of N, 17.0% by mass or more but less than 25.0% by mass of Cr, 4.0% by mass or more but less than 12.0% by mass of Ni, 7.0% by mass or more but less than 14.0% by mass of Mn, 2.0% by mass or more but less than 6.0% by mass of Mo, more than 0.5% by mass but less than 1.5% by mass of Si, and 0.025% by mass or more but less than 1.0% by mass of Nb, with the balance consisting of Fe and unavoidable impurities, in which a content of P contained in the unavoidable impurities is regulated to less than 0.03% by mass, a total content of C and N is from 0.85% by mass to 1.3% by mass, and a ratio of the content of Nb to the content of C is 0.05 or more but less than 1.8.
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