engleski

Fractographic characteristics of hydrogen charged CSP steel

In order to produce structural steels for ultra light steel auto body application, novel metallurgical technology i.e. continuous strip production, CSP is developed. Steels from CSP plants are characterized by multiphase microstructure containing martensite, bainite and/or retained austenite. Their prevention from environment sensitive fracture i.e. from hydrogen induced cracking, HIC is of a great importance. Therefore, the experiments were performed with steel coupons made from CSP and charged with hydrogen during cathodic polarization in two different media: BP solution (synthetic sea water) and 0.5 M H2SO4 solution. Tensile testing and metallographic observations have shown that hydrogenation has caused characteristic surface blistering and internal stepwise cracking in steel strip. Specimens charged in H2SO4 solution have shown higher susceptibility to hydrogen embrittlement. SEM/EDS analysis confirmed that ferrite- martensitic microstructure of steel strip contains intermetallic particles which contribute to HIC susceptibility.

environment sensitive fracture; CSP steel; hydrogenation

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