CN-117177833-B - Submerged arc welding head

Abstract

The invention provides a welded joint having a weld metal obtained by submerged arc welding with a line energy of 300kJ/cm or more. A submerged arc welding head wherein a weld metal has a specific composition, has a specific yield strength, tensile strength, and absorption energy of a V-notched Charpy impact test at a test temperature of 0 ℃, and wherein Ceq represented by the following formula (1) is in the range of 0.65 to 1.00, and wherein α represented by the following formula (2) is in the range of 6.0 or less .Ceq＝[C]+0.17[Mn]+0.04[Si]+0.025[Ni]+0.2[Cr]+0.25[Mo]…(1)α＝30[C]+0.7[Mn]+[Ni]-([Si]+0.5[Cr]+1.5[Mo])…(2), wherein [ element ] in the formula (1) and the formula (2) is the content (mass%) of the element in the weld metal.

Inventors

• TAKADA ATSUSHI
• ISHIGAMI TAKASHI
• WATANABE ICHISHI

Assignees

• 杰富意钢铁株式会社

Dates

Publication Date

20260512

Application Date

20220331

Priority Date

20210427

Claims (3)

1. 1. A submerged arc welding joint comprising a weld metal obtained by submerged arc welding with a welding wire and a flux, wherein the weld metal has a chemical composition, in mass%, of 0.05 to 0.15% C, 0.2 to 0.9% Si, 0.5 to 1.3% Mn, 0.015% or less P, 0.015% or less S, 0.10 to 0.45% Cr, 0.5 to 2.0% Mo, 2.5 to 6.0% Ni, 0.040% O, 0.012% or less N, the balance being Fe and unavoidable impurities, wherein Ceq represented by the following formula (1) is in the range of 0.65 to 1.00, alpha represented by the following formula (2) is in the range of 6.0 or less, the weld metal has a yield strength in a tensile test of 630MPa or more, and a tensile strength in the test of 780℃ or more is in the range of 0.47V-C, and the weld metal has an absorption coefficient of 0 to 47J-type in the test, Ceq=[C]+0.17[Mn]+0.04[Si]+0.025[Ni]+0.2[Cr]+0.25[Mo] ... (1) α=30[C]+0.7[Mn]+[Ni]-([Si]+0.5[Cr]+1.5[Mo]) ... (2) Here, the [ element ] in the formulas (1) and (2) is the mass% content of the element in the weld metal.
2. 2. The submerged arc welding head according to claim 1, further comprising one or more selected from the group consisting of 0.8% or less of Cu, 0.20% or less of Al, and 0.20% or less of Ti, in mass% based on the chemical composition of the weld metal.
3. 3. The submerged arc welding head according to claim 1 or 2, further comprising one or more selected from the group consisting of 0.10% or less of Nb, 0.10% or less of V, 0.010% or less of Ca, 0.010% or less of B, and 0.020% or less of REM, in mass% based on the chemical composition of the weld metal.

Description

Submerged arc welding head Technical Field The present invention relates to a submerged arc welding joint, and more particularly to a submerged arc welding joint having a weld metal obtained by submerged arc welding a 780 MPa-grade high-tension steel used in a building structure under a weld line energy of 300kJ/cm or more. Background In recent years, steel sheets used for steel frames tend to have high strength due to the enlargement and span of building structures. Conventionally, as an outer panel of a box column, mainly to a strength grade of 590 MPa-grade steel, 780 MPa-grade steel has been recently used. The joint of the outer panels of the box column is generally performed by submerged arc welding, and the strength of the weld metal is required to have strength characteristics equivalent to those of the base metal. As a welding material for submerged arc welding capable of securing a weld metal strength of 780MPa or more, for example, patent document 1 discloses a solid wire for submerged arc welding. It is described that by defining C, si, mn, ni, cr, mo, P, S of the total mass of the welding wire and adjusting ([ Mn ] + [ Ni ])/([ Cr ] + [ Mo ]) to 1.4 to 4.0, the low-temperature toughness and hydrogen embrittlement resistance sensitivity of the weld metal can be greatly improved. Patent document 2 discloses a submerged arc welding method for 780 MPa-level high-tension steel. It is described therein that by optimizing the amount of alloying elements in the sintered flux and the particle size of the flux, a good weld bead shape without slag mixing can be obtained, and by also limiting the chemical composition of the combined solid wire, a weld metal having a high strength of 780MPa or more and good low-temperature toughness can be obtained. Patent document 3 discloses a submerged arc welding wire for double-sided single-layer welding. It is described therein that in submerged arc welding of a double-sided single layer, in which the base metal is greatly diluted, the strength and toughness of the weld metal are ensured by limiting the composition of the weld wire, and further, the wire feed performance can be ensured by limiting the tensile strength of the weld wire to 1200N/mm 2 or less. Patent document 4 discloses a high-strength welded steel pipe having a weld metal excellent in low-temperature cracking resistance, wherein the tensile strength of both the base metal and the weld metal of the welded steel pipe manufactured by submerged arc welding of both sides from the inner surface and the outer surface is 800MPa or more. It is described that a weld metal having excellent low-temperature cracking resistance is obtained by specifying a CS value calculated from the content of Mo, ni, mn, C. Prior art literature Patent literature Patent document 1 Japanese patent application laid-open No. 2015-110241 Patent document 2 Japanese patent application laid-open No. 2015-120175 Patent document 3 Japanese patent application laid-open No. 2004-337863 Patent document 4 Japanese patent application laid-open No. 2008-240096 Disclosure of Invention Problems to be solved by the invention However, the weld line energy applied in patent documents 1 to 4 is 50kJ/cm or less. In the production of a box column using a steel material having a thickness of 590MPa or less as an outer panel, submerged arc welding having a weld line energy (hereinafter, also simply referred to as "line energy") of more than 300kJ/cm is generally used from the viewpoint of the efficiency of construction. However, when the welding materials disclosed in patent documents 1 to 4 are used for application at a line energy of 300kJ/cm or more, there is a problem that the strength of the weld metal is insufficient, toughness is insufficient, or high-temperature cracks are generated. The strength of the weld metal required here means that the weld metal produced in accordance with the regulation of JIS Z3111 has a yield strength (0.2% yield strength) at normal temperature of 630MPa or more and a tensile strength of 780MPa or more. The toughness of the weld metal required means that the absorption energy vE0 of the V-notched charpy impact test of the weld metal of the welded joint manufactured in accordance with the regulation of JIS Z3128 is 47J or more at the test temperature of 0 ℃. The purpose of the present invention is to solve the above problems and to provide a submerged arc welding head having a weld metal obtained by submerged arc welding with a line energy of 300kJ/cm or more. Means for solving the problems The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that it is effective to contain Ni in an amount of 2.5 mass% or more to ensure strength and toughness, which can improve strength without deteriorating toughness, and to adjust Ceq represented by the following formula (1) to 0.65 to 1.00. It was found that α represented by the following formula (2) may be adjusted to 6.0 or le