US Patent No. 10,065,272

SUPER HIGH-STRENGTH FLUX CORED ARC WELDED JOINT HAVING EXCELLENT IMPACT TOUGHNESS, AND WELDING WIRE FOR MANUFACTURING SAME


Patent No. 10,065,272
Issue Date September 04, 2018
Title Super High-strength Flux Cored Arc Welded Joint Having Excellent Impact Toughness, And Welding Wire For Manufacturing Same
Inventorship Hong-Chul Jeong, Pohang-si (KR)
Jin-Woo Lee, Pohang-si (KR)
Dong-Ryeol Lee, Pohang-si (KR)
Il-Wook Han, Pohang-si (KR)
Hong-Kil Lee, Pohang-si (KR)
Assignee POSCO, Pohang-si (KR)

Claim of US Patent No. 10,065,272

1. A flux-cored arc welded joint, comprising:0.01 wt % to 0.06 wt % of carbon (C), 0.1 wt % to 0.5 wt % of silicon (Si), 1.5 wt % to 3.0 wt % of manganese (Mn), 2.5 wt % to 3.5 wt % of nickel (Ni), 0.5 wt % to 1.0 wt % of molybdenum (Mo), 0.4 wt % to 1.0 wt % of copper (Cu), 0.4 wt % to 1.0 wt % of chromium (Cr), 0.035 wt % to 0.1 wt % of titanium (Ti), 0.003 wt % to 0.007 wt % of boron (B), 0.001 wt % to 0.006 wt % of nitrogen (N), 0.02 wt % (excluding 0) or less of phosphorus (P), 0.01 wt % (excluding 0) or less of sulfur (S), 0.03 wt % to 0.07 wt % of oxygen (O), and remaining iron (Fe) as well as unavoidable impurities; and
a mixed microstructure including acicular ferrite, bainite and martensite, wherein the mixed microstructure comprises: 40 area % or more of the acicular ferrite, and a 40-50% of the bainite and the martensite in an area fraction.