摘要 |
In a high-strength, quenched and tempered screw with a core and edge layer and with a product dimension of less than or equal to 250 Mn, consisting of a steel alloy with, in the melt, 0.7 to 1.0% by weight of mm, 0.7 to 2.2% by weight of Cr, 0.3 to 0.6% by weight of Mn, 0.5 to 2.2% by weight of Ni and at most 0.45% by weight of C, the remainder being iron and usual impurities, the core has been hardened and tempered to a tensile strength in the range from 1,180 to 1,300 N/mm<2>, namely at least 1,000 N/mm<2> at Rp 0.2. The edge layer has been hardened and tempered to a tensile strength in the range from 1,400 to 1,650 N/mm<2>, with Rp 0.2 at least 1,250 N/mm<2>. In general, the screw is subjected to inductive hardening and then annealed at above 300 DEG C.
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