Railroad tank cars formed of low-carbon, high toughness, steel plates

Abstract

A railroad tank car formed from steel alloy plates having improved toughness and puncture resistance. The steel alloy plates include a steel alloy including in wt. %: C: 0.1-0.15; Mn: 1.0-1.65; Si: 0.15-0.40; Al: 0.015-0.06; Mo: 0.1-0.3; Ni: 0.1-0.25; Nb: 0.015-0.045; Ti: up to 0.02; Cr: up to 0.22; V: up to 0.08; Cu: up to 0.35; P: max 0.025; S: max 0.015; and N: 0.004-0.01. The alloy plates may have been normalized for 30 minutes at 900° C. The alloy plates may have a tensile strength of at least 560 MPa; a yield strength of at least 345 MPa; a total elongation of at least 22%; a CVN impact toughness of at least 135.5J at −34.4° C.; a CVN impact toughness of at least 122J at −45.5° C. The alloy plates may have a ferrite-bainite microstructure, with 10% or less pearlite. The alloy plates of the inventive railroad tank car may have an absence of any banded ferrite-pearlite/martensite structure.

Dependencies are inferred from the claim text.