Evaluation of resistance of duplex steels to sulFidE stress cracking at various load modes

摘要

The paper deals with influence of various load modes and microstructural characteristics on evaluation of resistance of duplex steels 22CrO5Ni to sulfide stress cracking (SSC). Two heats of duplex steel were used. Each of these heats was evaluated both in as-supplied state after rolling and after homogenisation annealing, and also in the state after laboratory annealing by the mode 800 °C/5h/air. Microstructure of steel in the as-supplied state was ferritic-austenitic, in the state after annealing it was ferritic-austenitic with occurrence of the phase a at the majority phases interface. Testing of resistance of duplex steels was performed in accordance with the standard NACE TM 0177 by tensile test and by four-point bending test. The obtained results have confirmed influence of the used metallurgy of testing on final evaluation of resistance of duplex steels to SSC, as well as influence of microstructural characteristics, which manifested themselves namely by scope of corrosion attack of the samples and by different manner of crack propagation in the matrix.