TH174295B - High strength steel plate And methods for the production of steel sheets - Google Patents

Abstract

Disclosed is a steel plate of predetermined chemical composition and steel microstructure containing 15 % or more and 55 % or less of polygonal ferrite and 15 % or more of martensite and 30 % or less. less than 12 % or more of residual austenite as a volume fraction, including polygonal ferrite, martensite, and residual austenite. The average grain size is 4 micrometers or less, 2 micrometers or less, and 2 micrometers or less, respectively, and each has a length ratio. with an average grain width of 2.0 or less and wherein the value is obtained by dividing the Mn content in the retained austenite, % by mass, by the Mn content in the polyhedral ferrite, %. By mass, it will be equal to 2.0 or more.

Claims (1)

1.High strength steel plate that is assembled with Chemical elements containing C 0.030% or more and 0.250% or less, Si: 0.01% or more and 3.00% or less, Mn: more than 4.20% and 6.00% or less, P: 0.001% or more and 0.100% or less. Than S: 0.0001% or more and 0.0200% or less, N: 0.0005% or more, and 0.0100% or less, and Ti: 0.003% or more, and 0.200% or less, as% by mass and equal balance. g: