Evaluation of applicability of thick E500 TMCP and F500W QT steel plates for Arctic service

BackgroundThe paper presents a study of E500 TMCP European and F500W Russian Arctic shipbuilding thick steel plates. E500 steel plate (thermo-mechanically controlled process (TMCP), 25 mm thickness) and F500W steel plate (QT, 30 and 35 mm thickness) are designed for operation in Arctic conditions at temperatures as low as −40 and −60 °C, respectively.MethodsThe steels were evaluated in terms of base metal quality and welding performance. Welds and base metal were tested by methods described in International and Russian standards, namely the static tension test, Charpy V-notch impact test, drop weight test to determine nil-ductility transition (NDT) temperature, threepoint bending (Tkb) test, and crack tip opening displacement (CTOD) test. European E500 TMCP steel was evaluated according to the requirements of Russian standards; additionally, the research assesses the ability of E500 TMCP steel plates to meet the requirements of special tests required by the Russian Maritime Register of Shipping, such as Tkb and NDT tests.ResultsF500W QT obtains better results in special tests like NDT (−100 °C is better than −65 °C) and CTOD (CTOD −40 °C average 1.18 mm > 0.41 mm). Using quenching followed by high tempering enables possible operational temperatures down to −70 °C. However, the NDT test is required only in Russian standards. E500 steel base metal tests showed applicability based on criteria of the Charpy test at temperatures as low as −85 °C; based on criteria of NDT at −65 °C; based on Tkb criteria only at −40 °C; and CTOD test showed E500 applicability to as low as −55 °C. E500 welding tests showed, that Charpy impact toughness values are limiting the use of MMA welds to −20 °C, and FCAW and SAW welds can be utilized with some limitations at −40 °C. CTOD of the welded joint showed that E500 applicability at −40 °C is satisfactory just on the borderline of the standard requirements.ConclusionsThe test results showed fair performance for both the European and Russian steels. The steels were found to meet the requirements for Arctic application of both European and Russian standards.