| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonheat-treated steel which has suitable toughness within a use temperature range, and is easily fractured and separated not only in the conventional low temperature region including a cryogenic region for liquid nitrogen cooling or the like required by the object to be fractured, but also in an inexpensively reachable low temperature region, and to provide an engaged member fractured and separated at low temperatures. SOLUTION: The nonheat-treated steel easily fractured and separated at low temperatures has a composition comprising, by mass, 0.15 to 0.35% C, 0.5 to 2.0% Si, 0.5 to 1.5% Mn, 0.03 to 0.15% P, 0.01 to 0.15% S, 0.01 to 0.5% Cu, 0.01 to 0.5% Ni, 0.01 to 1.0% Cr, 0.001 to 0.01% s-Al, 0.005 to 0.035% N, 0.0001 to 0.01% Ca and 0.001 to 0.01% O, and satisfying 0.6≤Ceq≤0.85 and 0≤T<SB>Tr</SB>≤1.5, and the balance Fe with inevitable impurities. COPYRIGHT: (C)2004,JPO&NCIPI
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