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-2018363091-A1
Application number	US-201616062875-A
Country	US
Kind code	A1
Filing date	Dec 8, 2016
Priority date	Dec 22, 2015
Publication date	Dec 20, 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. Chemical composition is properly controlled for the steel plate and satisfies 1≤Ti/N≤6 and Mg/Ti>0.017, where effective S content in steel=S−1.3 Mg−0.8 Ca−0.34 REM−0.35 Zr, and effective S content in steel: 0.0003-0.003%; finely dispersed inclusions may be formed in the steel plate, and the amount of composite inclusion MgO+Ti 2 O 3 +MnS in the steel plate is controlled at a proportion greater than or equal to 5%. The tensile strength of a base material so acquired is ≥510 MPa, insofar as welding input energy is 200−400 kJ/cm, the average Charpy impact work of the steel plate at −40 ° C. is 100 J or more, 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%, P≤0.2%, S: 0.0015˜0.007%, Ni:0.2˜0.4% Ti: 0.005˜0.03%, Mg: 0.0005˜0.004%, N: 0.001˜0.006%, Al: 0.004˜0.036%, Ca≤0.003%, REM≤0.005%, Zr≤0.003%, and the balance of Fe and other inevitable impurities; wherein the chemical composition satisfies the following relationship:
1≤Ti/N≤6, Mg/Ti≥0.017;

the effective S content in steel=S−1.3Mg−0.8Ca−0.34REM−0.35Zr; the effective S content in steel: 0.0003˜0.003%; and the amount of composite inclusion MgO+Ti 2 O 3 +MnS in the steel plate is at a proportion of ≤5%.

2 . The thick steel plate for high heat input welding and having great heat-affected area toughness according to claim 1 , wherein the thick steel plate further comprises at least one element of Nb or Cr, and the amount of Nb is 0.03 wt % or less, and the amount of Cr is 0.2 wt % 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 tensile strength of the base material of the thick steel plate is ≥510 MPa, and when welding input energy is 200-400 kJ/cm, the average Charpy impact work of the welding heat-affected area of the steel plate at −40° C. is 100 J or more, 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 and casting comprising smelting, refining, continuous casting metal to obtain a slab for a steel plate having a chemical composition in weight percentage: C: 0.05˜0.09%, Si: 0.10˜0.30%, Mn: 1.2˜1.6%, P≤0.02%, S: 0.0015˜0.007%, Ni: 0.2˜0.4%, Ti: 0.005˜0.03%, Mg: 0.0005˜0.004%, N: 0.001˜0.006%, Al: 0.004˜0.036%, Ca≤0.0032%, REM≤0.005% , Zr≤0.003% , and a balance of Fe and other inevitable impurities; and, the chemical composition satisfying the following relationship:
1≤Ti/N≤6, Mg/Ti≥0.017;

an effective S content in steel=S−1.3Mg−0.8Ca−0.34REM−0.35Zr; an effective S content in steel: 0.0003˜0.003%; and the amount of composite inclusion MgO+Ti 2 O 3 +MnS in the steel plate is controlled at a proportion of≥5%; 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 cooling the surface temperature of the steel plate from 750° C. or more to 500° C. or less at a cooling rate of 2-20° C./s.

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 wt % or less, and the amount of Cr is 0.2 wt % 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 tensile strength of the 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.

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

Assignees

• Baoshan Iron & Steel

Inventors

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

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C22C38/12

  containing tungsten, tantalum, molybdenum, vanadium, or niobium · CPC title

• C21D6/008

  containing Si · CPC title

• C22C38/06

  containing aluminium · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title