Three-Electrode Narrow-Groove Welding to Inhibit Hot Cracking
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Solution Overview
Problem
Existing narrow-groove gas-shielded arc welding methods for forming second and additional layers are prone to hot cracking, limiting their efficiency and effectiveness.
Innovation Solution
A three-electrode welding method with controlled current values, polarity, and positioning for each electrode, using a mixed gas containing CO2, and rare earth metals in the welding wire, to inhibit hot cracking and enhance welding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-electrode welding is used for second and additional layers, then welding efficiency is improved, but hot cracking occurs in the weld bead surface
Solution Approach 1:
The invention changes the electrical parameters by specifying different current ranges for different electrodes based on their positions. The first electrode uses 150-250A, the second electrode uses 200-300A, and the third electrode uses 100-200A. This parameter differentiation optimizes the heat input distribution to prevent hot cracking while maintaining high welding efficiency.
Solution Approach 2:
The invention applies different current values to different electrodes based on their local positions and functions. Each electrode is assigned a specific current range tailored to its role in the welding process, creating localized quality control that prevents hot cracking in specific areas while maintaining overall welding efficiency.
2Productivity
If groove angle is reduced to 25° or less, then welding efficiency is improved, but welding difficulty increases
Solution Approach 1:
The invention segments the welding process into three separate electrodes, each handling a specific portion of the groove. This segmentation allows each electrode to work independently with optimized current parameters, making the narrow groove welding process more manageable and less difficult despite the tight 25° or less groove angle.
Solution Approach 2:
The third electrode acts as an intermediary that fills the groove root gap and controls the weld bead shape. By introducing this intermediate electrode with specific current parameters (100-200A), the invention mediates the complexity of narrow groove welding, reducing the overall difficulty while maintaining high efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves high welding efficiency with inhibited hot cracking, resulting in a cost-effective narrow-groove gas-shielded arc-welded joint suitable for structures like buildings, bridges, and ships.
Implementation Method 1
gas-shielded arc welding method that performs, by arc welding, multi-layer welding
Implementation Method 2
uses CO2 gas alone or a mixed gas of Ar and CO2 to shield the melted area
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(b)
Figure 3~4
AI summary
A welding method is provided, which is a multi-electrode narrow-groove gas-shielded arc welding method that can enable a high welding operation efficiency and can inhibit hot cracking. A narrow-groove gas-shielded arc welding method includes joining steel plates together by narrow-groove multi-layer welding, the steel plates having a thickness t of 22 mm or greater, the narrow-groove multi-layer welding using a groove angle θ of 25° or less and a groove root gap G0 of 7 mm to 18 mm, the narrow-groove gas-shielded arc welding method being a method adapted to be used for second and optionally additional layers associated with the multi-layer welding. In the method, the multi-layer welding uses three electrodes; a current value I1 of a first electrode and a current value I2 of a second electrode are each within a range of 260 A to 360 A; and, regarding an ith layer, a current value I3i [A] of a third electrode is within a range that satisfies inequality (1), shown below. I3i≤30×Gi−1−10 In the inequality, I3i is the current value [A] of the third electrode regarding the ith layer, Gi-1 is a width [mm] of a weld bead formed by welding for forming a layer immediately preceding the ith layer (i-1th layer), and i is a positive integer equal to or greater than 2.