STEEL MATERIAL Russian patent published in 2016 - IPC C22C38/14 C22C38/38 C22C38/28 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to steel used for making shock absorbing vehicle components. Steel has chemical composition, wt%: C: over 0.05 and up to 0.2, Mn: from 1 to 3, Si: over 0.5 and up to 1.8, Al: from 0.01 to 0.5, N: from 0.001 to 0.015, Ti or total content of vanadium and titanium: over 0.1 to 0.25, Cr: from 0 to 0.25, Mo: from 0 to 0.35, rest is iron and impurities. Steel has multiphase structure containing ferrite as main phase in amount of 50 % of area or more, and second phase containing at least one of bainite, martensite and austenite. Average nano strength of above mentioned second phase is less than 6.0 GPa. Boundary, at which crystals disorientation is 2° or more, is a grain boundary, and region bounded by grain boundary is a crystalline grain. Average grain diameter for all crystalline grains in said main phase and said second phase is equal to 3 mcm or less, and share of small-angle grain boundaries length, at which disorientation ranges from 2° to less than 15°, in all grain boundaries length is equal to 15 % or more.

EFFECT: steel has high value of absorbed shock power without formation of cracks at application of impact load.

6 cl, 2 dwg, 4 tbl, 1 ex