IDEA #7DDI1Y Hydrogen-Resistant Austenitic Steels

THE SCIENCE AND TECHNOLOGY CENTER IN UKRAINE HYDROGEN%RESISTANT AUSTENITIC STEELS Description The proposal concerns development of engineering materi(cid:28) als for service in hydrogenating environments. The approach is based on the electronic concept of hydrogen embrittlement (HE), studies of atomic interaction between hydrogen and alloying elements in steel and the effect of alloying elements on hydrogen migration, hydro(cid:28) gen(cid:28)induced phase transformations and mechanical prop(cid:28) erties of hydrogenated steels. It is shown that a reason for HE is the hydrogen(cid:28)caused increase in the concentration of free electrons leading to a striking decrease of the shear module, which results in a strongly modified mechanism of plastic deformation leading to pseudo(cid:28)brittle fracture. The developed concept is applicable for all not hydride(cid:28)forming metals.The knowledge of optimal chemical compositions of hydrogen(cid:28)resistant austenitic steels is obtained from the studies of Me(cid:28)H bonding energies in the solid solution, mobility of dislocations, hydrogen migration enthalpy and hydrogen(cid:28)induced phase transformations in relation to mechanical properties. It is shown that · nickel, be the widely used (and very expensive) alloying element in austenitic steels, is harmful for hydrogen resist(cid:28) ance, · alloying with elements increasing hydrogen migration enthalpy in steel is useful for hydrogen resistance, · alloying with elements enhancing the hydrogen(cid:28)induced fcc → hcp transformation is a promising way to develop hydrogen(cid:28)resistant steel. Fig. 2. Effect of chemical composition on hydrogen migration enthalpy and hydrogen embrittlement of austenitic steels Table 1. Effect of alloying elements in a model steel on hydro% gen%induced fcc →→ hcp transformation Innovative Aspect and Main Advantages · Cost(cid:28)effective high(cid:28)strength nonmagnetic austenitic steel with increased resistance to hydrogen brittleness. Areas of Application Automotive, aircraft, chemical and other industries Stage of development – Development phase – laboratory tested Areas of Application Automotive, aircraft, chemical and other industries Stage of Development – Development phase – laboratory tested Contact Details Institute for Metal Physics of the National Academy of Sciences of Ukraine 36, Vernadsky str., Kyiv, 03142, Ukraine Prof. Valentin Gavriljuk Tel+380(cid:28)44(cid:28)424(cid:28)3310 Fax +380(cid:28)44(cid:28)424(cid:28)3310 gavr@imp.kiev.ua Fig. 1. Stress%strain curve of hydrogen%free and hydrogen% charged steels. Effect of Ni in a model steel 76 SCIENCE AND INNOVATION. Special Issue, 2007