Abstract: Disclosed are a steel composition and a spring steel comprising the same. The steel composition comprises: an amount of about 0.51 to 0.57% by weight of carbon (C), an amount of about 1.35 to 1.45% by weight of silicon (Si), an amount of about 0.95 to 1.05% by weight of manganese (Mn), an amount of about 0.60 to 0.80% by weight of chromium (Cr), an amount of about 0.25 to 0.35% by weight of copper (Cu), an amount of about 0.05 to 0.15% by weight of vanadium (V), an amount of about 0.25 to 0.35% by weight of nickel (Ni), an amount of about 0.003 to 0.015% by weight of phosphorus (P), an amount of about 0.003 to 0.010% by weight of sulfur (S), and iron (Fe) constituting the remaining balance of the steel composition, all the % by weights are based on the total weight of the steel composition.

Abstract: Disclosed herein is a coil spring steel, comprising, by weight, carbon (C): about 0.51% to about 0.57%, silicon (Si): about 1.35% to about 1.45%, manganese (Mn): about 0.95% to about 1.05%, phosphorus (P): from about 0.003% to about 0.015%, sulfur (S): from about 0.003% to about 0.010%, chromium (Cr): from about 0.70% to about 0.90%, copper (Cu): from about 0.30% to about 0.40%, vanadium (V): from about 0.10% to about 0.15%, aluminum (Al): from about 0.010% to about 0.040%, titanium (Ti) from about 0.010% to about 0.033%, molybdenum (Mo): from about 0.05% to about 0.15%, nickel (Ni): from about 0.25% to about 0.35%, and a balance of iron (Fe) and inevitable impurities to form 100%.

Abstract: Disclosed are a steel composition and a spring steel comprising the same. The steel composition comprises: an amount of about 0.51 to 0.57% by weight of carbon (C), an amount of about 1.35 to 1.45% by weight of silicon (Si), an amount of about 0.95 to 1.05% by weight of manganese (Mn), an amount of about 0.60 to 0.80% by weight of chromium (Cr), an amount of about 0.25 to 0.35% by weight of copper (Cu), an amount of about 0.05 to 0.15% by weight of vanadium (V), an amount of about 0.25 to 0.35% by weight of nickel (Ni), an amount of about 0.003 to 0.015% by weight of phosphorus (P), an amount of about 0.003 to 0.010% by weight of sulfur (S), and iron (Fe) constituting the remaining balance of the steel composition, all the % by weights are based on the total weight of the steel composition.

Abstract: An ultra-high-strength spring steel, for use as a valve spring steel in a vehicle engine, includes 0.5 to 0.7% by weight of C, 1.2 to 1.5% by weight of Si, 0.6 to 1.2% by weight of Mn, 0.6 to 1.2% by weight of Cr, 0.1 to 0.5% by weight of Mo, 0.05 to 0.8% by weight of Ni, 0.05 to 0.5% by weight of V, 0.05 to 0.5% by weight of Nb, 0.05 to 0.3% by weight of Ti, 0.3% or less by weight of Cu (but not 0%), 0.0001 to 0.3% by weight of Al, 0.03% or less by weight of N (but not 0%), 0.0001 to 0.003% by weight of O, and a remainder of Fe and other unavoidable impurities, based on 100% by weight of the ultrahigh-strength spring steel.

Abstract: Provided are a coupon apparatus, user equipment, a service providing device, a control method thereof, and a non-transitory computer readable storage medium having computer program recorded thereon. That is, according to the present invention, it is possible to issue a coupon in a non-affiliated store and improve convenience of a user by easily issuing the coupon, by issuing the coupon according to a real-time sales situation of the store by a simple operation in a non-affiliated/affiliated store.