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-10837089-B2
Application number	US-201616062880-A
Country	US
Kind code	B2
Filing date	Dec 8, 2016
Priority date	Dec 22, 2015
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

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+Al 2 O 3 +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

The invention claimed is:

1. A thick steel plate for high heat input welding and having great heat-affected area toughness, 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 a 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, and wherein the steel plate consists essentially of 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 and (Ca+REM+Zr)/Al≥0.11;

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

2. A thick steel plate for high heat input welding and having great heat-affected area toughness, 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 a 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, and wherein the steel plate consists essentially of 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%,
Nb: ≤0.03% or Cr≤0.2%, and
the balance of Fe and other inevitable impurities;
wherein the chemical composition satisfies the following relationship:
1≤Ti/N≤6 and (Ca+REM+Zr)/Al≤0.11;
an effective S content in steel=S-0.8Ca-0.34REM-0.35Zr which is in a range of 0.0006-0.005%; and
the proportion of composite inclusion CaO+Al 2 O 3 +MnS+TiN in the steel plate is 12% or more.

3. 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 the thick 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°-6, 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, which is in a range of 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% of total inclusions;
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%; and
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.; and
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 a 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. The method of manufacturing a thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 3 , 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.

Assignees

• Baoshan Iron & Steel

Inventors

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

Classifications

• C21D1/60

  Aqueous agents · CPC title

• C21D1/56

  characterised by the quenching agents · CPC title

• C21D7/13

  by hot working · CPC title

• C21D1/02

  Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation · CPC title

• C21D1/84

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