Thick steel plate for high heat input welding and having great heat-affected area toughness and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-2018371587-A1
Application number	US-201616062880-A
Country	US
Kind code	A1
Filing date	Dec 8, 2016
Priority date	Dec 22, 2015
Publication date	Dec 27, 2018
Grant date	—

Abstract

A thick steel plate for high heat input welding and having great heat-affected area toughness and a manufacturing method therefor, comprising the steps of smelting, casting, rolling, and cooling. Also, the chemical composition of the steel plate satisfies 1≤Ti/N≤6 and (Ca+REM+Zr)/Al≥0.11, where the effective S content in steel=S-0.8Ca-0.34REM-0.35Zr. and the effective S content in steel: 0.0006-0.005%; finely dispersed inclusions may be formed, and the amount of composite inclusion CaO+Al2O3+MnS+TiN in the steel plate is at a proportion of ≥12%. With respect to welding in which the thickness of the steel plate is 50-70 mm, the tensile strength of a base material is ≥510 MPa. and welding input energy is 200-400 kJ/cm, the average Charpy impact work of a welding heat-affected area of the steel plate at −40 ° C. is 100 J or more, and at the same time, the average Charpy aging impact work of the base material of ½ thickness at −40° C. is 46 J or more.

First claim

1 . A thick steel plate for high heat input welding and having great heat-affected area toughness, comprising a chemical composition in mass percentage:
C: 0.05˜0.08%, Si: 0.10˜0.30%, Mn: 1.2˜1.6 9%, P≤0.02%, S: 0.002˜0.008%, B: 0.0005˜0.005%, Ni: 0.20˜0.40%, Cu: 0.15˜0.3%, Ti: 0.005˜0.03%, Al: 0.003˜0.03%, Ca: 0.001˜0.0050%, REM≤0.01%, Zr≤0.01%, N: 0.001˜0.006%, and the balance of Fe and other inevitable impurities; wherein the chemical composition satisfies the following relationship:
1≤Ti/N≤6,(Ca+REM+Zr)/Al≤0.11;

an effective S content in steel=S-0.8Ca-0.34REM-0.35Zr; an effective S content in steel: 0.0006˜0.005%; and the amount of composite inclusion CaO+Al 2 O 3 +MnS+TiN in the steel plate is at a proportion of ≥12%.

2 . The thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 1 , wherein the steel plate further comprises at least one element of Nb or Cr, and the amount of Nb is 0.03 mass % or less, and the amount of Cr is 0.2 mass % or less.

3 . The thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 1 , wherein the thickness of the steel plate is 50-70 mm, the tensile strength of a base material of the steel plate is ≥510 MPa, the average Charpy impact work of the welding heat-affected area of the steel plate at −40° C. is 100 J or more under the condition that welding input energy is 200-400 kJ/cm, and the average Charpy aging impact work of the base material of ½ plate thickness at −40° C. is 46 J or more.

4 . A method of manufacturing a thick steel plate for high heat input welding and having great heat-affected area toughness, wherein the method comprises the following steps:
1) smelting, refining and continuous casting comprising smelting, refining, continuous casting metal to obtain a slab for a steel plate having a chemical composition in mass percentage: C: 0.05˜0.08%, Si: 0.10˜0.30%, Mn: 1.2˜1.6%, P≤0.02%, S: 0.002˜0.008%, B: 0.0005˜0.005%, Ni: 0.20˜0.40%, Cu: 0.15˜0.3%, Ti: 0.005˜0.03%, Al: 0.003˜0.03%, Ca: 0.001˜0.005%, REM≤0.01%, Zr≤0.01%, N: 0.001˜0.006%, and the balance of Fe and other inevitable impurities; wherein the chemical composition satisfies the following relationship: 1≤Ti/N≤6, (Ca+REM+Zr)/Al≤0.11; an effective S content in steel=S-0.8Ca-0.34REM-0.35Zr; an effective S content in steel: 0.0006˜0.005%; and the amount of composite inclusion CaO+Al 2 O 3 +MnS+TiN in the steel plate is controlled at a proportion of ≥12%; 2) rolling comprising heating the slab to 1050-1250° C., wherein initial rolling temperature is higher than 930° C., cumulative reduction rate is greater than 30%, and wherein finish rolling temperature is less than 930° C., and cumulative reduction rate is greater than 30%; 3) cooling comprising performing water cooling at a cooling rate of 2 to 30° C./s to a final cooling temperature of 300 to 550° C.

5 . The method of manufacturing a thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 4 , wherein the thick steel plate further comprises at least one element of Nb or Cr, the amount of Nb is 0.03 mass % or less, and the amount of Cr is 0.2 mass % or less.

6 . The method of manufacturing a thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 4 , wherein the thickness of the steel plate is 50-70 mm, the tensile strength of a base material for the steel plate is ≥510 MPa, the average Charpy impact work of the welding heat-affected area of the steel plate at −40° C. is 100 J or more under the condition that welding input energy is 200-400 kJ/cm, and the average Charpy aging impact work of the base material of ½ plate thickness at −40° C. is 46 J or more.

7 . The thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 2 , wherein the thickness of the steel plate is 50-70 mm, the tensile strength of a base material of the steel plate is ≥510 MPa, the average Charpy impact work of the welding heat-affected area of the steel plate at −40° C. is 100 J or more under the condition that welding input energy is 200-400 kJ/cm, and the average Charpy aging impact work of the base material of ½ plate thickness at −40° C. is 46 J or more.

8 . The method of manufacturing a thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 5 , wherein the thickness of the steel plate is 50-70 mm, the tensile strength of a base material for the steel plate is ≥510 MPa, the average Charpy impact work of the welding heat-affected area of the steel plate at −40° C. is 100 J or more under the condition that welding input energy is 200-400 kJ/cm, and the average Charpy aging impact work of the base material of ½ plate thickness at −40° C. is 46 J or more.

Assignees

• Baoshan Iron & Steel

Inventors

• Yang Jian
• Gao Shan
• Ma Zhigang
• Wang Ruizhi
• Zhang Caiyi
• Wang Junkai
• Xu Guodong
• Wang Yunan

Classifications

• C22C38/26

  with niobium or tantalum · CPC title

• C21D1/84

  Controlled slow cooling (cooling-beds for metal rolling B21B43/00) · CPC title

• C22C38/08

  containing nickel {(C22C38/105 takes precedence)} · CPC title

• C21D1/56

  characterised by the quenching agents · CPC title

• C21D6/008

  containing Si · CPC title