Posco

Jeong-Bong Yoon

Sang-Ho Han

Sung-Il Kim

Kwang-Geun Chin

Won-Ho Son

Jai-Ik Kim

Man-Young Park

Noi-Ha Cho

Jong-Hwa Kim

Byoung-Ho Lee

Seung-Hee Lee

Ki-Bong Kang

Ki-Duck Park

Hee-Man Son

Jin-Hee Chung

There are provided a steel sheet for resistance to composite corrosion from sulfuric acid and hydrochloric acid, having excellent wear resistance and surface quality, and a method of manufacturing the same. The steel sheet having excellent surface qualities may be provided by improving resistance to erosion occurring due to coal cinders to increase a lifespan thereof and securing excellent resistance to composite corrosion from sulfuric acid and hydrochloric acid. Wear resistance may be significantly increased by adding P, and in order to solve a problem in that wear resistance is deteriorated due to the addition of P, a component system and a hot rolling process condition may be controlled, thereby forming a corrosion resistant layer having excellent corrosion resistance.

Steel for resistance to complex corrosion from hydrochloric acid and sulfuric acid, having excellent wear resistance and surface qualities

A cold rolled steel sheet, and a method of manufacturing the same, designed to have aging resistance and excellent formability suitable for use in automobile bodies, electronic appliances, and the like. The cold rolled steel sheet comprises in weight %: 0.003% or less of C, 0.003&#x2dc;0.03% of S, 0.01&#x2dc;0.1% of Al, 0.02% or less of N, 0.2% or less of P, at least one of 0.03&#x2dc;0.2% of Mn and 0.005&#x2dc;0.2% of Cu, and a balance of Fe and other unavoidable impurities. When the steel sheet comprises one of Mn and Cu, the composition of Mn, Cu, and S satisfies at least one relationship: 0.58*Mn/S&#x2266;10 and 1&#x2266;0.5*Cu/S&#x2266;10, and when the steel sheet comprises both Mn and Cu, the composition of Mn, Cu, and S satisfies the relationship: Mn+Cu&#x2266;0.3 and 2&#x2266;0.5*(Mn+Cu)/S&#x2266;20. Participates of MnS, CuS, and (Mn, Cu)S in the steel sheet have an average size of 0.2 &#x3bc;m or less. Since carbon content in a solid solution state in a crystal grain is controlled by fine precipitates of MnS, CuS, or (Mn, Cu)S, the steel sheet has enhanced aging resistance and formability, and has excellent yield strength and strength-ductility.

Cold rolled steel sheet having aging resistance and superior formability, and process for producing the same

Provided are a steel sheet for an automotive muffler and a method for producing the steel sheet. The steel sheet includes 0.01% by weight or less of C, 0.1 to 0.3% by weight of Si, 0.3 to 0.5% by weight of Mn, 0.015% by weight or less of P, 0.015% or less by weight of S, 0.02 to 0.05% by weight of Al, 0.004% or less of N, 0.2 to 0.6% by weight of Cu, 0.01 to 0.04% by weight of Co, and a remainder of Fe and unavoidable impurities. The method includes 0.01% by weight or less of C, 0.1 to 0.3% by weight of Si, 0.3 to 0.5% by weight of Mn, 0.015% by weight or less of P, 0.015% or less by weight of S, 0.02 to 0.05% by weight of Al, 0.004% or less of N, 0.2 to 0.6% by weight of Cu, 0.01 to 0.04% by weight of Co, and a remainder of Fe and unavoidable impurities, preparing a hot rolled steel sheet by re-heating the steel slab and by, during a finish rolling process, hot-rolling the steel slab at a temperature that is an Ar3 transformation temperature or more, preparing a cold rolled steel sheet by cold-rolling the hot rolled steel sheet with a cold reduction ratio of 50 to 90%, and performing a continuous annealing for the cold rolled steel sheet at a temperature of 500 to 900&#xb0; C.

Corrosion resistance improved steel sheet for automotive muffler and method of producing the steel sheet

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Pohang-si, South Korea

Jeong-Bong Yoon