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Welding method for NM400 wear-resistant steel

A welding method and technology of wear-resistant steel, applied in welding equipment, welding/welding/cutting items, arc welding equipment, etc., can solve problems such as large carbon equivalent, high cost, and complicated welding process, and achieve improved surface wear resistance , wear resistance integration, simple welding process effect

Active Publication Date: 2014-12-24
CHONGQING HUAYU HEAVY IND ELECTROMECHANICAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, since the NM400 wear-resistant steel plate is a low-alloy structural steel with a large carbon equivalent, it has an obvious tendency to cold cracks, and problems such as cold cracks and softening and embrittlement of the heat-affected zone will occur during welding.
In actual production, this type of steel is mainly used for welding with low-carbon steel, and requires preheating before welding and heat preservation after welding. The welding process is complicated and the cost is high. Most of them use MIG or mixed welding. Gas shielded welding (MAG) and other mechanized or semi-mechanical methods with equal strength welding wire for welding
However, the welded structure using this welding process often has super strong weld root, local hardening and insufficient toughness during use, which is easy to cause cracks in the weld
And it is often difficult to take overall preheating and heat preservation for large structural parts

Method used

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  • Welding method for NM400 wear-resistant steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Embodiment 1: comprise the steps:

[0025] (1) Pretreatment before welding;

[0026] Make a single-sided V-shaped groove at the butt joint, with a groove angle of 45°, a blunt edge of 2mm, and a root gap of 1.5mm; use a wire brush to clean the groove and the 40mm surface on both sides of the groove to remove oil and rust until exposed Metallic luster; use A407 electrode for spot welding according to the required structure and fix it for welding;

[0027] (2) Weld the bottom seam;

[0028] The bottom layer 4 welds are arc welded with manual electrodes, the electrode grade is A407, and its material is C=0.08~0.20, Mn=1.0~2.5, Si≤0.75, Cr=25.0~28.0, Ni=20.0~22.5, using φ5. 0 electrode, welding current is 200A ， The arc voltage is 22V, the welding speed is 10cm / min, the strip transport method adopts the straight line transport method, the weld seam width is 5mm, and the weld seam thickness is 4mm;

[0029] (3) The middle layer 3 is welded;

[0030] Flame heating the we...

Embodiment 2

[0035] Embodiment 2: comprise the steps:

[0036] (1) Pretreatment before welding;

[0037] Make a single-sided V-shaped groove at the butt joint, with a groove angle of 50°, a blunt edge of 1.5mm, and a root gap of 2mm; use a wire brush to clean the groove and the 40mm surface on both sides of the groove to remove oil and rust until it is exposed Metallic luster; use A407 electrode for spot welding according to the required structure and fix it for welding;

[0038] (2) Weld the bottom seam;

[0039] The bottom layer 4 welds are arc welded with manual electrodes, the electrode grade is A407, and its material is C=0.08~0.20, Mn=1.0~2.5, Si≤0.75, Cr=25.0~28.0, Ni=20.0~22.5, using φ5. 0 electrode, welding current is 200A ， The arc voltage is 22V, the welding speed is 10cm / min, the strip transport method adopts the straight line transport method, the weld seam width is 5mm, and the weld seam thickness is 4mm;

[0040] (3) The middle layer 3 is welded;

[0041] Flame heating th...

Embodiment 3

[0046] Embodiment 3: comprise the steps:

[0047] (1) Pretreatment before welding;

[0048] Make a V-shaped groove on one side and one side at the T-shaped joint, with a groove angle of 60°, a blunt edge of 2mm, and a root gap of 2mm; 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 metallic luster is exposed; use A407 electrode for spot welding according to the required structure and fix it for welding;

[0049] (2) Weld the bottom seam;

[0050] The welding seam of the bottom layer is arc welding with manual electrode. The welding rod, the welding current is 200A, the arc voltage is 22V, and the welding speed is 10cm / min.

[0051] (3) Intermediate layer welding;

[0052] Flame heating the welding seam and its surrounding area of ​​200mm, using an infrared thermometer to measure the temperature up to 350°C, and keeping the temperature constant for 5 minutes; the middle layer welding seam uses ER50-6 we...

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Abstract

The invention provides a welding method for NM400 wear-resistant steel. The welding method comprises the following steps: after adopting an A407 stainless steel electrode as a bottoming welding joint, locally preheating the welding joint and the area in peripheral 200mm scope, wherein the preheating temperature is 350-400 DEG C and the temperature is kept constant for 5 minutes; performing multilayer multichannel welding by using an ER50-6 welding stick matched with CO2 gas protection welding, wherein the height of each layer of welding joint is not more than 4mm and the interlayer temperature is controlled to be above 150 DEG C; using the A407 stainless steel electrode for welding a transition layer at the height of 2-3 layers of welding joints from the surface of a base metal, wherein the thickness of the transition layer is more than 3mm; lastly, using a D212 electrode for covering and polishing the surplus height of the welding joint and welding toe, wherein the surplus height of the welding joint is not more than 3mm. Preheating before welding is not required, heat insulation after welding is not required, the welding technique is simple and the cost is low. The toughness of an NM400 wear-resisting steel welding joint is improved and the integration of the strength, toughness and wear-resistance of the joint is realized.

Description

technical field [0001] The invention belongs to the field of steel plate welding technology, and in particular relates to a welding method of NM400 wear-resistant steel. Background technique [0002] In recent years, with the rapid development of mines and various construction machinery, people have put forward higher requirements for the service life of the wearing parts on the equipment. As a special steel with high mechanical strength and high surface hardness, wear-resistant steel is widely used in the processing and manufacturing of wear-resistant and wearing parts of mines and various construction machinery to improve the service life of machinery and reduce production costs. Such as: excavator, loader, bulldozer bucket plate, edge plate, side edge plate, blade. Crusher liners, blades. [0003] NM400 is a kind of wear-resistant steel plate. NM-indicates the first letter of the Chinese pinyin of "resistant" and "grinding" for wear-resistant purposes, and 400 is the B...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K9/00B23K9/16B23K9/235
CPCB23K9/00B23K9/02B23K9/16B23K9/235B23K33/00B23K2103/04
Inventor 赖建勋吴忠保金彬
Owner CHONGQING HUAYU HEAVY IND ELECTROMECHANICAL CO LTD
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