Development of a steel grade 9 Cr 1 Mo reinforced with V, Nb, N for use at high temperature
Project ID: 7210-KF/304Funded under: ECSC-STEELRES 7C
This work has demonstrated the ability to manufacture heavy plates (up to 300 mm) of steel 9 Cr 1 Mo V Nb N (grade 91 in ASTM standards) with satisfactory tensile and impact mechanical properties. For the application of such heavy plates to the manufacturing of pressure vessels for use at high temperature and possibly with hydrogen pressure, the research has been developed in the fields of weldability and of hydrogen behaviour of the material, in comparison with 2.25 Cr 1 Mo steel. The weldability, considering the sensitivity of the steel to cracking phenomena during welding and PWHT, may be considered as equivalent to that of the reference material 2.25 Cr 1 Mo. However, the welding products evaluated in this research appeared to be unsatisfactory for their creep resistance. The behaviour of this steel 91, under hydrogen pressure, offers a higher resistance than 2.25 Cr 1 Mo at high temperature (hydrogen attack). The embrittlement due to hydrogen is lower for steel grade 91 than for 2.25 Cr 1 Mo as evaluated by ductility or fracture mechanics tests, for the same hydrogen content in the steel. However, it has been found that steel grade 91 is more susceptible than 2.25 Cr 1 Mo steel to absorb hydrogen during operation of the pressure vessel.
Bibliographic Reference: EUR 14545 FR (1993) 74 pp., FS, ECU 9
ISBN: ISBN 92-826-5070-7
Record Number: 199310424 / Last updated on: 1994-11-29
Original language: fr
Available languages: fr