ELONGATED MEMBER AND A STEEL FOR PERCUSSION BORING Russian patent published in 2005 - IPC

FIELD: metallurgy and mechanical engineering.

SUBSTANCE: the invention is pertaining to the field of metallurgy and mechanical engineering, in particular, to development of the corrosion-resistant steel for percussion boring with improved properties concerning resistance to the corrosive fatigue. These properties are realized in the in the elongated member for the percussion boring, which has a threading and a flushing channel. The corrosion-resistant steel used for production of the boring equipment has the martensite structure with the share of the martensite from more than 50 and up to less than 100 mass % and contains Cr ≥11÷ mass % and 0.1 mass % ≤ C + N 0.8 mass %. The steel may additionally contain Mo ≤5 mass %, W ≤5 mass % and Cu ≤ 2 mass %. The composition of the steel meets the value of the index of the equivalent of resistance to a pitting corrosion (ERPC) > 10, determined according to the formula: ERPC = Cr + 3.3 (Mo + W) + 16 N, where Cr, Mo, W and N correspond to the contents of the indicated elements (in mass percents). The content of the martensite in the steel makes from 75 up to 98 mass %. The standard service life of the drill rods used for the core drilling at boring a rock - mainly from granite has increased up to 2189÷3299 drilled meters.

EFFECT: the invention ensures significantly increased standard service life of the drill rods used for the core drilling at boring a rock - mainly from granite(in drilled meters).

8 cl, 2 dwg, 1 ex