Mannesmann Aktiengesellschaft

Klaus Haarmann

Ingo Von Hagen

Walter Bendick

A high-temperature steel for boiler making having improved creep strength and low tendency to hardening in welded condition, having the following melt analysis (wt. %): C 0.050 to 0.100% Si 0.15 to 0.45% Mn 0.30 to 0.70% P .ltoreq.0.020% S .ltoreq.0.010% Al .ltoreq.0.020% Cr 2.20 to 2.60% Mo 0.90 to 1.10% V 0.20 to 0.30% Ti 0.05 to 0.10% B 0.0015 to 0.0070% N .ltoreq.0.01% The balance of the steel is comprised of iron and ordinary impurities. The steel is annealed for a period of about 30 to about 60 minutes at about 980.degree. C. to about 1040.degree. C., thereupon cooled in air, and then tempered for at least one hour at about 730.degree. C. to about 760.degree. C.

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Ratingen, Germany

Klaus Haarmann