One-Sided Submerged Arc Welding for Thick Plate Low-Heat Input
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Solution Overview
Problem
Conventional one-sided submerged arc welding methods for thick steel plates result in increased groove cross-sectional area with plate thickness, leading to higher heat input, impaired low-temperature toughness, and mechanical property deterioration due to excessive heat, and require additional equipment and increased costs.
Innovation Solution
A one-sided submerged arc welding method with X-shaped double grooves on both the front and back surfaces, reduced groove depths, and optimized groove angles, using two to four electrodes with controlled welding current and speed to minimize heat input and ensure complete penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the groove cross-sectional area is increased to accommodate thicker steel plates, then the welding capacity is improved, but the heat input increases excessively causing low-temperature toughness impairment
Solution Approach 1:
The groove is divided into two separate grooves: a first groove on the front surface and a second groove on the back surface. This segmentation allows each groove to have a smaller cross-sectional area compared to a single large groove, thereby reducing the total heat input required while maintaining the ability to weld thick steel plates effectively.
Solution Approach 2:
The solution moves from a single-dimensional groove (front surface only) to a two-dimensional approach by adding a groove on the back surface. This dimensional change allows the welding process to distribute heat input more effectively across the joint, reducing excessive heat accumulation while maintaining welding capacity for thick plates.
2Productivity
If the welding current or number of electrodes is increased to maintain productivity, then the wire supply rate is improved, but the cooling speed reduces causing crystal grain coarsening
Solution Approach 1:
The welding process is segmented into multiple passes with alternating electrode polarity. The first electrode (DCEN) creates deep penetration with lower current, while the second electrode (DCEP) follows to fill the groove. This segmentation allows maintaining adequate wire supply rate without requiring excessively high current that would reduce cooling speed and cause grain coarsening.
3Temperature
If the groove angle is narrowed to reduce cross-sectional area, then the heat input is reduced, but arc generation in upper region causes incomplete penetration
Solution Approach 1:
The groove configuration is segmented into front and back surfaces with different groove angles optimized for their respective functions. The front surface groove angle is optimized for arc stability and penetration initiation, while the back surface groove angle is optimized for completing penetration and preventing arc escape. This segmentation allows each groove to have optimal angles that prevent incomplete penetration while maintaining reduced heat input.
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 achieves high-strength welds with excellent low-temperature toughness and productivity, reducing the need for additional equipment and costs while maintaining efficient welding processes for thick steel plates.
Implementation Method 1
welding is performed by causing an arc to burn between an electrode wire and the steel plates
Implementation Method 2
a flux layer is spread on both a front surface and a back surface of the steel plates, and one-sided welding is performed from the front surface side with the flux layer therebetween
Data Source
AI summary
A highly productive submerged arc welding method ensuring excellent mechanical properties when welding thick steel plates at high heat inputs in the fields of shipbuilding, construction and so on; a weld joint produced using such welding method; and a production method for such weld joint. The welding method is a one-sided submerged arc welding method for welding two butted steel plates, in which grooves are formed on both a front and a back surface side of the steel plates, root faces are formed between the groove on the front surface side and the groove on the back surface side, and welding is performed from the front surface side. It is preferred that a root face height be 2 to 5 mm, and that a groove depth on the back surface side be 2 to 5 mm.