Development Programs on Irradiation Embrittlement of Low Alloy Pressure Vessel Steels in the Federal Republic of Germany

Neutron embrittlement of pressure vessel steels has been investigated in the Federal Republic of Germany for several years.

The most important pressure vessel steel irradiation program was carried out by Kernforschungsanlage Jülich on behalf of Verein Deutscher Eisenhüttenleute (VDEh) which was completed by the end of 1973.

Four types of low alloys steels have been investigated.

MnNiMo steel: 0.22C, 1.4Mn, 0.012P, 0.6Ni, 0.5Mo, 0.12Cu

(according to ASTM Specification forPressure Vessel Plates, Alloy Steel, Quenched and Tempered, Manganese-Molybdenum and Manganese-Molybdenum-Nickel (A 533-7 B)) as reference material provided by the Heavy Section Steel Program Committee

MnNiMo V steel: O.riC, 1.3Mn, 0.012P, 1.5Ni, 0.4Mo, (UlCu, 0.15V

NiCrMo steel: 0.15C, 0.34Cr, 0.010P, 3.2Ni\ 0.4Mo, 0.15Cu

NiCrMo steel: 0.19C, 1.6Cr, 0.010P, 3.8Ni, 0.5Mo, 0.15Cu

The steels were available as base material longitudinal, as base material transversal, as weld submerged arc, and as weld heat affected zone.

The objective of this program was to determine the influence of neutron fluence and irradiation temperature on the impact and tensile properties of the materials.

The program of VDEh will be continued. This rogram will investigate the influence of microstructure and the impurities, copper and phosphorus. The materials under investigation are 22NiMoCr37 (according to ASTM Specification for Quenched and Tempered Vacuum Treated Carbon and Attoy Steel Forgings for Pressure Vessels (A 508-74) and 20MnMoNi55 (ASTM Method A 533-74).