Mannesmann Aktiengesellschaft

Bernhard Hoffmann

Ingo Von Hagen

Dieter Vespermann

Heinz Muller

A process for the manufacture of a seamless pressure vessel and the seamless pressure vessel produced thereby, the process including the steps of employing an aluminum-killed CrMo steel which includes by wt. %: 0.28-0.39% C; 0.15-0.40% Si; 0.45-0.90% Mn; max. 0.02% P; max. 0.005% S; 0.90-1.30% Cr; 0.15-0.35% Mo; 0.0010-0.040% Ti; 0.001-0.003% B; and 0.003-0.010% N; hot working the alumninum-killed CrMo Steel to produce the seamless pressure vessel, austenizing the seamless pressure vessel at a temperature between about 830.degree. C. and about 880.degree. C.; cooling the seamless pressure vessel at a cooling rate of between about 5.degree. K/s and about 15.degree. K/s; and tempering the seamless pressure vessel at a temperature between about 510.degree. C. and about 660.degree. C.

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Hunxe, Germany

Bernhard Hoffmann