| 摘要 |
PURPOSE:To obtain a shank material used for strengthening the insole material of shoes by forming a flat plate with subzero cooling treatment hardened type martensite stainless steel satisfying the specific condition and punching the plate into the predetermined shape. CONSTITUTION:This stainless steel has an austenite structure in an annealed condition and is transformed into a martensite structure when subjected to subzero cooling treatment. Depending upon the composition, the stainless steel is classified into the first and second types. The first type of the stainless sheel contains 0.4% or less of carbon, 0.4% or less of nitrogen, 15% or less of manganese, 12% or less of nickel, 10 to 23% or less of chromium, 3.0% or less of molybdenum, 0.5% or less of copper, 2.0% or less of silicon and the rest of impurities and iron, respectively by the weight percentage ratio. The constituents satisfy formulae 1 and 2. In the second type of the stainless steel, the contents of manganese, nickel and copper are so modified that 4% or less of manganese, 3% or less of nickel and 2.0% or less of copper are respectively contained, and the constituents satisfy formulae 1, 2 and 4. A shank material 10 is formed with the first or second type of the stainless steel, and fitted to the back of an insole material 15 together with a lining material 16, using an eyelet 17. Furthermore, the product so obtained is processed into the predetermined shape via a press and the shank material 10 is subjected to subzero cooling treatment. |
