SELECTION AND APPLICATION OF AN AUSTENITIC STAINLESS STEEL FOR THE FABRICATION OF THE PRESSURE VESSEL FOR THE FAST REACTOR RAPSODIE
The responsibility for the selection of a suitable stainless steel for the design and fabrication of the pressure vessel of the French fast reactor RAPSODIE led to an investigation of the effect of several material, welding, and heat treating variables on the properties of welded joints. Investigated were niobium and titanium stabilized stainless steel, molybdenum containing stainless steels, and a stainless steel containing both molybdenum and boron. These materials were welded with coated electrodes or welding rods in a protective argon atmosphere and a variety of tests were made on the base materials themselves and on the welded test pieces. Creep rupture tests up to 16000 hours and at temperatures ranging from 550 to 650 deg C under loads of up to 60 Kg/mm/ sup 2/ were carried out. The tests were supplemented with impact tests on notched and plain specimens, hardness measurements, metallographic examinations, and determinations of the reduction of area as a measure of high temperature ductility. The effect of a stress relief treatment at 1050 deg C and cooling to a predetermined lower temperature at the rate of 50 deg C/hr and subsequent cooling in air was studied. As a result of the tests molybdenum, tungsten, and manganese were considered to be favorable alloying elements of the base material while boron, titanium, and niobium were considered to be unfavorable. The hot ductility of the titanium and niobium stabilized stainless steels was particularly poor. Molybdenum additions gave satisfactory results and molybdenum plus boron additions gave excellent results. The selection of the electrodes and the welding rod materials was governed by the same considerations as that of the base materials. Creep rupture tests on actual welded joints frequentiy showed a marked decrease of creep rupture strength when compared with that of the base metal, sometimes by a factor of ten. However, experiments with the composition 17 Cr-l3 Ni-2 Mo plus boron showed no such decrease. Rupture occurred always in the welds and with greater rupture ductility. Other molybdenum containing alloys also behaved in the same way. It was concluded that a satisfactory vessel can be fabricated by using an austenitic stainless steel with molybdenum additions and partially ferritic electrodes of the 18 Cr-11 Ni-2 Mo type having a rigorously controlled delta ferrite content. A full scale mock-up of the reactor vessel was built without any welding incidents. (P.C.H.)
- Research Organization:
- Euratom, Brussels and Commissariat a l'Energie Atomique, Paris
- NSA Number:
- NSA-18-015565
- OSTI ID:
- 4064191
- Journal Information:
- Met. Soc., Am. Inst. Mining, Met. Petrol. Engrs., Inst. Metals Div., Spec. Rept. Ser., Vol. Vol: No. 12; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ACCIDENTS
AIR
ARGON
ATMOSPHERE
AUSTENITE
BORIDES
BORON
BREEDING
CHROMIUM ALLOYS
COATING
COOLING
CREEP
DUCTILITY
ELECTRODES
FABRICATION
FAILURES
FAST NEUTRONS
HARDNESS
HEAT TREATMENTS
HIGH TEMPERATURE
IMPACT SHOCK
IRON OXIDES
JOINTS
MANGANESE
MATERIALS TESTING
MEASURED VALUES
METALLOGRAPHY
MOCKUP
MOLYBDENUM
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NIOBIUM
PLANNING
PRESSURE
PRESSURE VESSELS
RAPSODIE
REACTORS
RODS
STABILITY
STAINLESS STEELS
STRESSES
TESTING
TITANIUM
TUNGSTEN
VESSELS
WELDING