1976 Volume 62 Issue 13 Pages 1708-1719
he heavy section low alloy steel plates are used for pressure vessels for nuclear reactor, desulfurizer of crude oil and so on. The integrity in quality, therefore, is required for those plates.
The factor affection the internal soundness and notch toughness of heavy section low alloy steel plates are discussed in relation to the rolling process from ingot to plate and the heat treatment after rolling.
Theoretical analysis concerning constrained yield stress in rolling direction was applied for the rolling of extremely thick plate and it is concluded that adapting high “shape factor”, that is, high reduction in the stage of final pass in the rolling process is effective to reduce internal defects in plates.
Precipitation behavior of aluminum nitride in A553B steel plate during heat treatment after rolling is discussed in relation to the austenite grain size and notch toughness of plate after final rolling, and cooling down to 400°C before normalizing is recommended for obtaining good notch toughness.
Selection of temperature and time for dehydrogenation at ferrite region is discussed and it is shown that the optimum temperature for dehydrogenation must be determined by taking the microsegregation in the plate into consideration.
