PURPOSE: To prevent deterioration in strength, toughness, workability and corrosion resistance even after subjected to welding plural times, by controlling the compositional limit values of Cr, C, N, Ni, Nb, etc., respectively.
CONSTITUTION: A steel used for purposes where welding is applied plural times and having a composition which consists of, by weight, <0.035% C, <0.02% N, 0.1W0.5% Si, 0.1W0.8% Mn, 11W17% Cr, 0.8W3.0% Ni, 0.005W0.03% Al, 0.05W0.35% Nb, 0.05W0.8% Cu, and the balance Fe with inevitable impurities and in which (C+N) and Nb/(C+N) are regulated to <0.05% and 2.5W7, respectively, and also the value of CRE represented by an equation is regulated to 5W20 is prepared. A steel sheet of the above composition is heated to the prescribed temp. and air-cooled, if necessary, by which the steel excellent in toughness, composed of massive martensitic structure, having ≥about 60kgf/mm2 yield strength, and used for purposes in which welding is applied plural times to produce bicycle rim can be prepared.
YAMANAKA MIKIO
ICHIKAWA MASASHI
YAMAMOTO AKIO
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