CHARACTERISTICS MARKS AND PRODUCTION METHODS OF HIC RESISTANT PRESSURE VESSEL STEELS

摘要

Although the term HIC resistant is widely used, the meaning is not sufficiently clear. It is mostly applied to materials having limited crack dimensions in an HIC test according to NACE standard TM0284 or similar.rnIn the first part it is pointed out, that there is a fundamental difference between steels produced as HIC resistant and only HIC tested steels. The former one are intentionally produced to get a stable and reproducible material behaviour especially HIC resistance, not only in the tested sample but throughout the whole delivered tonnage. This is achieved by applying a specific steelmaking and plate manufacturing route combined with a specially adapted quality assurance system. For the later one the HIC test could have been performed only as an upgrading test on a part of material which is expected, e.g. based upon steel analysis, to have satisfactory HIC test results. Even if a locally good HIC test result is obtained by chance, it is not necessarily representative for all parts of the plate and the order.rnUnalloyed or low alloyed as HIC resistant produced steels, e.g. A516 Gr70, up to now are mainly produced as normalized steels. The second part of the paper describes two other approaches: These are the Q&T (quenched plus tempered), and the TMCP (Thermo-Mechanical Control Process) types. The benefits and limitations are explained.