Submerged Arc Welding of Thick Steel Plates
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Solution Overview
Problem
Current welding technologies are inadequate for efficiently welding ultra-heavy steel plates with thicknesses over 50 mm, particularly in cold areas, as they fail to provide weld metal with sufficient toughness and high heat input efficiency for wind power generation facilities.
Innovation Solution
A submerged arc welding method using a digitally controlled AC/DC welding power supply with optimized flux composition and waveform control, allowing for one-run welding of double V grooves in steel plates with plate thicknesses between 50 mm and 100 mm, utilizing alternating currents and specific flux components like Al2O3, SiO2, MgO, TiO2, CaF2, and MnO to enhance wire feed speed and reduce heat input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high heat input welding is used to weld thick steel plates efficiently, then welding productivity is improved, but the toughness of the weld metal deteriorates
Solution Approach 1:
The welding process is segmented into multiple passes (root pass, intermediate passes, cap pass) with different heat input levels and welding parameters optimized for each stage, allowing efficient welding while maintaining toughness through controlled heat distribution
Solution Approach 2:
Welding parameters such as current, voltage, welding speed, and heat input are dynamically adjusted across different passes and positions to optimize both productivity and weld metal toughness, with specific parameters changed based on the welding stage and required material properties
2Device complexity
If one-side single layer welding is used to reduce groove cross-sectional area, then manufacturing complexity is reduced, but the welding heat input becomes excessively high
Solution Approach 1:
The welding process is divided into multiple passes (root pass, intermediate passes, cap pass) that progressively build the weld, distributing the heat input across multiple stages rather than requiring excessive heat in a single pass, thereby reducing total heat input while maintaining process simplicity
Solution Approach 2:
The root pass is performed first to establish proper penetration and fusion, followed by intermediate passes that build up the weld profile, allowing subsequent passes to be performed with optimized heat input since the groove geometry is already established
3Adaptability or versatility
If conventional welding methods are used for steel plates over 50 mm thick, then existing equipment can be utilized, but the weld metal toughness at low temperatures is insufficient
Solution Approach 1:
Welding parameters including current type (AC/DC), waveform ratio, heat input level, and welding speed are specifically adjusted to produce weld metal with enhanced low-temperature toughness while using conventional welding equipment, with parameters optimized for cold environment performance
Solution Approach 2:
The welding process creates a composite microstructure in the weld metal through controlled cooling rates and heat input, resulting in a microstructure that combines the benefits of conventional welding with enhanced toughness properties suitable for cold environments
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
This method enables highly efficient welding of steel plates with improved toughness at low temperatures, facilitating the efficient manufacturing of wind power generation facility bases in cold areas and contributing to the proliferation of renewable energy.
Implementation Method 1
a welding current for a first electrode is an alternating current with a waveform ratio of 60% or greater and 90% or less, and welding currents for the other electrodes are an alternating current with a waveform ratio of 70% or greater, or a negative direct current
Implementation Method 2
the flux consists of, in a mass ratio to a total mass of the flux: Al 2 O 3 : 10% or greater and 50% or less; and SiO 2 : 16% or greater and 30% or less, and further includes: one or more of MgO, TiO 2 , CaF 2 , and MnO
Data Source
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AI summary
This method of submerged arc welding includes: a machining step of machining a double V groove; and a welding step of performing a one-run welding with a flux. In the welding step, a welding current for a first electrode is an alternating current with a waveform ratio of 60% or greater and 90% or less, and welding currents for the other electrodes are an alternating current with a waveform ratio of 70% or greater, or a negative direct current. The flux includes, in a mass ratio to a total mass of the flux, 10% to 50% of Al2O3: and 16% to 30% of SiO2, and further includes: one or more of MgO, TiO2, CaF2, and MnO, a total of which is 10% to 60%, the MgO, TiO2 CaF2, and MnO being limited to not more than 40%, 20%, 30%, and 20%, respectively.