A martensitic heat resistant steel is provided which has improved {TAIL ~ high temperature creep strength}, contains Co and, at a temperature of 600° C. or above, does not form an intermetallic compound substantially having a composition of {HEAD ~ Cr40 Mo20 Co20} W10 C2 Fe 
A martensitic heat resistant steel is provided which has improved { TAIL ~ high temperature creep strength } , contains Co and , at a temperature of 600 ° C. or above , does not form an intermetallic compound substantially having a composition of { HEAD ~ Cr40 Mo20 Co20 } W10 C2 Fe
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