Q690 and Q980 high-strength dissimilar steel non-preheating welding method

A welding method and technology of dissimilar steel, applied in welding equipment, welding medium, welding equipment, etc., can solve the problems of increasing the softening tendency of the heat affected zone, complicated welding process, super strong weld root, etc., and achieve a smooth surface of the weld. Beautiful appearance, good application prospects, and the effect of avoiding cold cracks

Inactive Publication Date: 2012-06-27
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the welded structure using this welding process often has super strong weld root, local hardening and insufficient toughness during use, which easily leads to cracks at the weld root
Especially welding 980MPa high-strength steel under preheating conditions will increase the softening tendency of the heat-affected zone, and the welding process is complicated and the production cost is high
Especially for large welded structures, it is difficult to preheat the overall structure to a certain temperature in actual production when using preheat welding

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Butt welding of Q690 and Q980 high-strength dissimilar steels with a thickness of 20mm, the size of the test plate is 200mm×150mm×20mm. Using Ar+CO 2 Mixed gas arc welding (MAG) for welding, Ar and CO 2 The gas volume ratio is 85%:15%.

[0026] (1) Welding equipment and welding materials

[0027] The welding equipment adopts the inverter welding machine with good dynamic characteristics; the mixed gas shielded welding adopts 700MPa solid core welding wire with a diameter of 1.2mm for filling welding and 800MPa flux cored welding wire with a diameter of 2.0mm for cover welding, and the oil and rust on the surface of the welding wire are removed before welding. Wait for dirt.

[0028] (2) Preparation before welding

[0029] The joints of Q690 steel and Q980 steel with a thickness of 20mm are respectively made V-shaped grooves by grinding with a grinding wheel. The angle of the groove is 20° on one side and the blunt side is 2mm. Clean up the rust and oil dirt within ...

Embodiment 2

[0037] H-shaped welded structure with a thickness of 25mm, the two vertical plates are made of Q980 high-strength steel, and the horizontal plate is made of Q690 steel, connected by fillet welds. The size of the vertical plate is 300mm×200mm×25mm, and the size of the horizontal plate is 200mm×200mm×25mm. Using Ar+CO 2 Mixed gas shielded welding method, in which Ar and CO 2 The volume ratio of gas is 80%:20%.

[0038] (1) Welding equipment and welding materials

[0039] The welding equipment adopts the inverter welding machine with good dynamic characteristics; the gas shielded welding adopts 700MPa solid-core welding wire with a diameter of 1.2mm for filling welding and 800MPa flux-cored welding wire with a diameter of 2.0mm for cover welding, and removes oil and rust on the surface of the welding wire before welding dirt.

[0040] (2) Preparation before welding

[0041] The Q690 high-strength steel horizontal plate with a thickness of 25mm is machined to open double V-sh...

Embodiment 3

[0050] Butt welding of Q690 and Q980 high-strength dissimilar steels with a thickness of 30mm, using Ar+CO 2 Mixed gas arc welding (MAG) for welding, Ar and CO 2 The gas volume ratio is 90%:10%.

[0051] (1) Welding equipment and welding materials

[0052] The welding equipment adopts the inverter welding machine with good dynamic characteristics; the gas shielded welding adopts 700MPa solid-core welding wire with a diameter of 1.2mm for filling welding and 800MPa flux-cored welding wire with a diameter of 2.0mm for cover welding, and removes oil and rust on the surface of the welding wire before welding dirt.

[0053] (2) Preparation before welding

[0054] Open a V-shaped groove at the joint of the workpiece to be welded, with a single-sided groove angle of 30° and a blunt edge of 2.5mm; use a wire brush to clean the groove and the 40mm surface on both sides of the groove to remove oil and rust until the metal is exposed Gloss; use mixed gas shielded welding 700MPa solid...

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Abstract

The invention discloses a Q690 and Q980 high-strength dissimilar steel non-preheating welding method. A bottom layer of a to-be-welded workpiece adopts low-match 700-800MPa high-strength high-toughness welding wires, and adopts argon and carbon dioxide (Ar+CO2) mixed gas shield welding. A welding bead of a bottoming layer adopts 700MPa high-strength high-toughness solid wires, and a surface covering layer adopts 800MPa high-strength flux-cored wires. In a welding process, welding heat input is strictly controlled, and diffusible hydrogen content of welding lines is controlled at a super-low hydrogen level. The mixing ratio of argon and carbon dioxide of mixed gas shield welding is 75-95%Ar: 25-15CO2. By adopting the process without pre-heating or post-weld heat treatment to weld Q690 and Q980 high-strength dissimilar steel, welding joints which have no internal cracks can be obtained. An area of joints is flat and smooth, tensile strength at room temperature of weld metal is larger than 760MPa, and V-notch impact absorbing energy of weld metal at test temperature 0 DEG C is larger than 68J, thereby meeting the requirement of a high-strength dissimilar steel welding structure for high carrying capacity.

Description

technical field [0001] The invention relates to a high-strength steel welding method without preheating, in particular to a welding method for Q690 and Q980 high-strength dissimilar steels without preheating and post-weld heat treatment, and belongs to the field of welding technology. Background technique [0002] In recent years, with the advancement of metallurgical technology, low-alloy high-strength steel (Q980) with a yield strength of 980 MPa has attracted attention, especially the high-strength dissimilar steel structure formed by welding Q980 steel and low-alloy steel (Q690) with a yield strength of 690 MPa. is even more advantageous. The high-strength dissimilar steel welded structure can not only meet the steel requirements of different working conditions, but also reduce costs and simplify the manufacturing process, and give full play to the performance advantages of steel with different strength levels. This high-strength dissimilar steel welded structure has br...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K9/16B23K9/235B23K33/00B23K35/368
Inventor 李亚江李嘉宁王娟
Owner SHANDONG UNIV
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