High-Strength Low-Carbon Ferritic Steel Containing Cu-Fe-Ni-Al-Mn Precipitates

• DOI: 10.1007/s11661-007-9417-x
• Publication Date: 2008-01-08T17:15:33Z
• Authors: Semyon Vaynman; Dieter Isheim; R. Prakash Kolli; Shrikant P. Bhat; David N. Seidman; Morris E. Fine
• Keywords: Charpy impact test; Carbon fibers; Brittleness; Atom probe; Elongation; Carbon steel

An investigation of a low-carbon, Fe-Cu–based steel, for Naval ship hull applications, with a yield strength of 965 MPa, Charpy V-notch absorbed impact-energy values as high as 74 J at –40 °C, and an elongation-to-failure greater than 15 pct, is presented. The increase in strength is derived from a large number density (approximately 1023 to 1024 m−3) of copper-iron-nickel-aluminum-manganese precipitates. The effect on the mechanical properties of varying the thermal treatment was studied. The nanostructure of the precipitates found within the steel was characterized by atom-probe tomography. Additionally, initial welding studies show that a brittle heat-affected zone is not formed adjacent to the welds.