Hyundai Motor Company

Kia Motors Corporation

Korea Institute of Science and Technology

Hyundai Steel Company

Bong Lae Jo

Chang Won Kang

Jae Hong Park

Dong Hwi Kim

Sung Chul Cha

Jae Hyeok Shim

Hye Min Jo

Sang Min Song

Disclosed herein is a ferritic steel having decreased specific gravity and having excellent mechanical strength by suppressing formation of &#x3ba;-carbide. The ferrite steel may include: carbon (C) in an amount of about 0.05 to 0.12 wt %; aluminum (Al) in an amount of about 3.0 to 7.0 wt %; manganese (Mn) in an amount of about 0.5 wt % or less (not 0%); nickel (Ni) in an amount of about 0.5 wt % or less (not 0%); chromium (Cr) in an amount of about 0.75 wt % or less (not 0%); silicon (Si) in an amount of about 0.3 to 0.75 wt %; a combined amount of titanium (Ti) and vanadium (V) in an amount of about 0.25 to 0.7 wt %; and a balance being iron (Fe), all the wt % are based on the total weight of the ferritic steel.

Ferritic steel

An ultra-high-strength spring steel for an engine valve spring steel comprises, by weight: 0.5-0.7% of carbon (C), 1.3-2.3% of silicon (Si), 0.6-1.2% of manganese (Mn), 0.6-1.2% of chrome (Cr), 0.1-0.5% of molybdenum (Mo), 0.05-0.8% of nickel (Ni), 0.05-0.5% of vanadium (V), 0.05-0.5% of niobium (Nb), 0.05-0.3% of titanium (Ti), 0.001-0.01% of boron (B), 0.01-0.52% of tungsten (W), 0.3% or less (0% exclusive) of copper (Cu), 0.3% or less (0% exclusive) of aluminum (Al), 0.03% or less (0% exclusive) of nitrogen (N), 0.003% or less (0% exclusive) of oxygen (O), and a remainder of Fe and other inevitable impurities, based on 100% by weight of the ultra-high-strength spring steel.

Ultra-high-strength spring steel for valve spring

A method of manufacturing a light rotor shaft for eco-friendly vehicles is provided which includes cutting a pipe material in a specified length to provide a pipe blank and forming the pipe blank to provide a first form having the first segment on a first side. The method further includes, forming a second form having the second segment by inserting and rotating a first side of a mandrel into the first side of the first form and concurrently hammer-forging the second side of the first form to form the second segment. The rotor shaft includes a third segment formed by inserting and rotating the second side of the mandrel into the first side of the second form to form the third segment.

Method of manufacturing light rotor shaft for eco-friendly vehicles

Disclosed herein is a high-strength transmission gear, manufactured by gas-nitriding a nitriding steel having a composition including iron (Fe) as a main component, 0.25&#x2dc;0.40 wt % of carbon (C), 0.50&#x2dc;1.0 wt % of manganese (Mn), 2.0&#x2dc;3.0 wt % of chromium (Cr), 0.3&#x2dc;1.0 wt % of molybdenum (Mo), 0.2&#x2dc;0.7 wt % of copper (Cu), 0.03&#x2dc;0.1 wt % of niobium (Nb), 0.03&#x2dc;0.1 wt % of aluminum (Al), 0.05&#x2dc;0.15 wt % of vanadium (V), 0.001&#x2dc;0.005 wt % of boron (B) and other inevitable impurities. More specifically, while gas-nitriding of the nitriding steel, the temperature is increased in steps, and the ratio of nitrogen gas in the nitriding steel is decreased in steps.

High-strength transmission gear and method of manufacturing the same

Disclosed is a carburization heat treatment method including carburizing a workpiece at a relatively low temperature within a temperature range of A&#x2dc;Ausing a vacuum carburizing furnace and then performing quenching using a high-pressure gas, in which the workpiece is made of typical carburizing alloy steel having a carbon content of about 0.10&#x2dc;0.35 wt %. This method can be applied to carburization heat treatment of a steel workpiece sensitive to heat deformation, such as an annulus gear, in lieu of a conventional gas carburization method using plug quenching.

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Gyeonggi-do, South Korea

Bong Lae Jo