POSCO Holdings Inc.
COLD-ROLLED STEEL SHEET HAVING EXCELLENT HIGH-TEMPERATURE PROPERTIES AND ROOM-TEMPERATURE WORKABILITY, AND METHOD FOR MANUFACTURING SAME

Abstract:

The present disclosure provides a cold-rolled steel sheet having excellent high-temperature properties and room-temperature workability, including, by weight: carbon (C): 0.0005 to 0.003%, manganese (Mn): 0.20 to 0.50%, aluminum (Al): 0.01 to 0.10%, phosphorus (P): 0.003 to 0.020%, nitrogen (N): 0.0005 to 0.004%, sulfur (S): 0.015% or less, niobium (Nb): 0.005 to 0.040%, chromium (Cr): 0.10 to 0.50%, tungsten (W): 0.02 to 0.07%, and a balance of iron (Fe) and other inevitable impurities, wherein C, Nb, and W satisfy the following relationship 1, a microstructure comprises 95 area % or more of polygonal ferrite and 5 area % or less of acicular ferrite, and the cold-rolled steel sheet comprises (Nb,W)C-based precipitates having an average size of 0.005 to 0.10 .mu.m and a method for manufacturing the same: 0.00025.ltoreq.(2.times.Nb/93).times.*W/184)/(C/12).ltoreq.0.0015 [Relationship 1] where, C, Nb, and W are in weight %.