| 摘要 |
<p>PURPOSE: A heat-treatment hardening steel sheet with excellent low-temperature impact toughness and a manufacturing method thereof are provided to produce a steel sheet having a transition temperature range of -80°C or below and also a high tensile strength of 1200~1500 MPa. CONSTITUTION: A heat-treatment hardening steel sheet with excellent low-temperature impact toughness comprises carbon(C) 0.19~0.40 weight%, manganese(Mn) 0.5~2.5 weight%, chrome(Cr) 0.1~0.5 weight%, boron(B) 0.0015~0.0040 weight%, silicon(Si) 0.5 weight% or less, phosphorus(P) 0.05 weight% or less, sulfur(S) 0.05 weight% or less, aluminum(Al) 0.03 weight% or less, molybdenum(Mo) 0.05~1.0 weight%, and the remnant Fe and inevitable impurities. The steel sheet also includes one or more among nickel(Ni) 2 weight% or less, niobium(Nb) 0.10 weight% or less, and copper(Cu) 1.0 weight% or less.</p> |
