HEAT-RESISTANT MARTENSITE ALLOY EXCELLENT IN HIGH-TEMPERATURE CREEP RAPTURE STRENGTH AND DUCTILITY AND PROCESS FOR PRODUCING THE SAME

摘要

The present invention provides a martensitic heat resistant alloy having a composition (A) comprising, % by weight: 0.03 to 0.15% of C; 0.01 to 0.9% of Si; 0.01 to 1.5% of Mn; 8.0 to 13.0% of Cr; 0.0005 to 0.015% of Al; no more than 2.0% of Mo; no more than 4.0% of W; 0.05 to 0.5% of V; 0.01 to 0.2% of Nb; 0.1 to 5.0% of Co; 0.008 to 0.03% of B; less than 0.005% of N: and Fe and inevitable impurities as the remainder, wherein (B) the contents (% by weight) of Mo, W, B and N satisfy the following formulae (1) and (2).$\[ \text{B - 0.772N 0.007} \]$$\[ \text{W + 1.916Mo - 16.99B 2.0} \]$;The martensitic heat resistant alloy of the present invention has excellent oxidation resistance, hot workability and ductility and exhibits high creep rupture strength in a range of relatively long rupture time at a high temperature.