Abstract: Disclosed is a process for producing seamless steel pipes or flat products (strip or sheet) for pipes or vessels which are intended for the conveyance, transport or processing of gaseous or liquid hydrocarbons containing CO.sub.2 and water and possibly small proportions of H.sub.2 S and are resistant to stress crack corrosion and have good welding properties at the same time and a 0.2-percent elongation limit of at least 450 N/mm.sup.2. The process uses a nickel-containing steel of the following composition (percent by weight): min. 0.015% C, 0.15-0.50% Si, max. 2.00% Mn, max. 0.020% P, max. 0.003% S, 12.0-13.8% Cr, 0.002-0.02% N, 0.01-0.05% Nb, remainder iron and usual impurities. It is presently suggested that the nickel content is limited to a maximum of 0.25%, the manganese content amounts to at least 1.0%, the carbon content is limited to 0.035%, and 0.01 to 1.2% molybdenum is contained as additional alloying component.

Abstract: A method of improving the resistance to H-induced stress-corrosion cracking of articles of low- to medium-alloy structural steels which come into contact with aqueous H.sub.2 S-containing fluids and which are manufactured by one of (i) hot rolling, with or without subsequent heat treatment, (ii) by TM-rolling, with or without accelerated cooling, and (iii) by cold rolling with subsequent heat treatment and which are then cold strained from 0% to less than 2%. In order to economically increase the resistance of articles of structural steel to H-induced stress-corrosion cracking, the articles are subjected to a final annealing for a period of at least two seconds at a temperature which is at least 540.degree. C. and the upper limit of which is as follows: In the case of hot rolled or TM-rolled or normalized articles, 30K below A.sub.C1 ; in the case of hardened and tempered articles, 30K below the tempering temperature last employed.