# US 10,864,605 B2 · High strength welding joint having excellent impact toughness at very low temperature, and flux-cored arc welding wire therefor

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- Number: US 10,864,605 B2
- Document ID: US10864605B2
- Status: Granted
- Kind: B2
- Application number: 16/189,232
- Filed: 2018-11-13
- Published: 2019-03-21
- Granted: 2020-12-15
- Earliest claimed: 2013-12-06
- Assignees: Posco
- Applicants: Posco
- Inventors: Bong-Keun Lee; Sang-Chul Lee; Il-Wook Han; Jeong-Kil Kim
- Web page: https://patentgrep.com/patent/US10864605B2

## CPC

- B23K 35/3073: {with Mn as next major constituent}
- B23K 35/0266: {flux-cored}
- B23K 35/30: with the principal constituent melting at less than 1550°C
- B23K 35/3053: {Fe as the principal constituent}
- B23K 35/3086: {containing Ni or Mn}
- C22C 38/001: {containing N}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/18: containing chromium
- C22C 38/22: with molybdenum or tungsten
- C22C 38/28: with titanium or zirconium
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/48: with niobium or tantalum
- C22C 38/50: with titanium or zirconium
- C22C 38/54: with boron
- C22C 38/58: with more than 1.5% by weight of manganese
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

A high strength welding joint having excellent toughness at low temperature obtained by welding a cryogenic high-strength high-Mn steel, comprising 0.1-0.61 wt % of C, 0.23-1.0 wt % of Si, 14-35 wt % of Mn, 6 wt % or less of Cr, 1.45-3.5 wt % of Mo, 0.02 wt % or less of S, 0.02 wt % or less of P, 0.001-0.01 wt % of B, 0.001-0.2 wt % of Ti, 0.001-0.3 wt % of N, and balance of Fe and inevitable impurities; and a flux-cored arc welding wire comprising 0.15-0.8 wt % of C, 0.2-1.2 wt % of Si, 15-34 wt % of Mn, 6 wt % or less of Cr, 1.5-4 wt % of Mo, 0.02 wt % or less of S, 0.02 wt % or less of P, 0.01 wt % or less of B, 0.1-0.5 wt % of Ti, 0.001-0.3 wt % of N, 4-15 wt % of TiO2, 0.01-9 wt % of at least one of SiO2, ZrO2 and Al2O3, 0.5-1.7 wt % of at least one of alkali elements including K, Na, and Li, 0.2-1.5 wt % of at least one of F and Ca, and balance of Fe and inevitable impurities.

## Claims

### Claim 1

A flux-cored arc welding wire having a high degree of strength and a high degree of cryogenic impact toughness, the flux-cored arc welding wire comprises, wt %, carbon (C): 0.15% to 0.8%, silicon (Si): 0.2% to 1.2%, manganese (Mn): 15% to 34%, chromium (Cr): 6% or less, molybdenum (Mo): 1.5% to 4%, sulfur (S): 0.02% or less, phosphorus (P): 0.02% or less, boron (B): 0.01% or less, titanium (Ti): 0.09% to 0.5%, nitrogen (N): 0.001% to 0.3%, TiO2: 4% to 15%, at least one selected from SiO2, ZrO2, and Al2O3: 0.01% to 9% in total content, at least one selected from potassium (K), sodium (Na), and lithium (Li): 0.5% to 1.7% in total content, at least one of fluorine (F) and calcium (Ca): 0.2% to 1.5%, and a balance of iron (Fe) and inevitable impurities.

### Claim 2 (depends on 1)

The flux-cored arc welding wire of claim 1, further comprising at least one selected from tungsten (W), niobium (Nb), and vanadium (V) in a total amount of 5 wt % or less.

### Claim 3 (depends on 1)

The flux-cored arc welding wire of claim 1, further comprising yttrium (Y) and/or a rare earth metal (REM) in an amount of 1 wt % or less.

### Claim 4 (depends on 1)

The flux-cored arc welding wire of claim 1, further comprising nickel (Ni) in an amount of 10 wt % or less.