Heat treatment of heavy section low alloy steel plates

Heavy section low alloy steel plates are used for nuclear reactor and direct oil desulfurizing reactor pressure vessels, etc. High integrity is, therefore, required of these steel plates. The factors which affect the internal soundness and notch toughness of heavy section low alloy steel plates are discussed in relation to heat treatment after rolling. Precipitation behavior of aluminum nitride in A533B steel plates during heat treatment after rolling is described with respect to the austenite grain size and notch toughness of the plate after final rolling. Cooling down to 4000C before normalizing is recommended to obtain good notch toughness. Selection of temperature and time for dehydrogenation at the ferrite region is discussed and it is shown that the optimum temperature for dehydrogenation must be determined by taking microsegregation in the plate into consideration. (author)