| 摘要 |
<p>PURPOSE: A method of manufacturing high strength steel for LPG of a level of 500MPa and high strength steel are provided to compensate for a decrease in strength due to post processing by introducing enhancement of strength due to deformation reinforcing and precipitation reinforcing by adding Mo to Ni steel. CONSTITUTION: A method of manufacturing high strength steel for LPG of a level of 500MPa comprises next steps. Steel is re-heated(S100). The re-heated steel is hot rolled(S200). The hot rolled steel is normalized(S300). The normalized steel is air-cooled(S400). The steel consists of C 0.08~0.15 weight%, Si of 0.2~0.3 weight%, Mn of 0.5~1.2 wwight%, P of 0.01~0.02 weight%, S of 0.004~0.006 weight%, Ti of 0.01 weight% or less, Mo of 0.05~0.1 weight%, Ni of 3.0~5.0 weight%, Fe and other inevitable impurities. The re-heating of the steel is practiced at a temperature of 1100~1200°C. The normalizing of the steel is practiced at a temperature of 840~880°C.</p> |
