Special Welding Torch Suction Nozzle for Low-Hydrogen Flux-Cored Wire
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Solution Overview
Problem
The welding industry faces challenges with hydrogen embrittlement and cracking in high tensile strength steel welds due to diffusible hydrogen, particularly with seamed flux cored wires that absorb moisture, leading to high hydrogen content and reduced weldability and efficiency.
Innovation Solution
A welding method using a special torch with a suction nozzle and a seamed flux cored wire, where the torch effectively reduces diffusible hydrogen by discharging moisture from the seam portion during welding, improving weldability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preheating and post-heating are performed to reduce diffusible hydrogen, then hydrogen embrittlement and cracking are prevented, but energy consumption and labor costs increase significantly
Solution Approach 1:
The flux is pre-heated during the wire manufacturing process to vaporize hydrogen sources before the wire is used for welding. This preliminary removal of hydrogen sources eliminates the need for post-welding preheating and post-heating operations, significantly reducing energy consumption while preventing hydrogen embrittlement and cracking
Solution Approach 2:
Hydrogen sources (moisture and organic matters) are extracted from the flux through high-temperature heating during manufacturing. By removing these hydrogen sources in advance, the weld metal produced subsequently contains minimal diffusible hydrogen, preventing cracking without requiring additional heating operations
2Reliability
If fluoride is added to the flux to reduce diffusible hydrogen, then hydrogen cracking susceptibility is reduced, but arc stability deteriorates
Solution Approach 1:
Instead of adding fluoride to chemically bind hydrogen, the invention extracts hydrogen sources (moisture and organic matters) from the flux through high-temperature heating during manufacturing. This physical removal approach reduces diffusible hydrogen without introducing fluoride, thereby maintaining arc stability
Solution Approach 2:
The manufacturing process parameters are changed to include high-temperature heating of the flux, which vaporizes hydrogen sources. This parameter change achieves hydrogen reduction through thermal processing rather than chemical additives, preserving arc stability
3Reliability
If CF4 is mixed into the shielding gas to reduce diffusible hydrogen, then hydrogen cracking is prevented, but arc stability deteriorates and safety concerns arise
Solution Approach 1:
Hydrogen sources are removed from the flux during manufacturing through high-temperature heating, before welding begins. This preliminary action eliminates the need to add CF4 to shielding gas, maintaining arc stability and avoiding safety concerns associated with CF4
Solution Approach 2:
Hydrogen sources are extracted from the flux through thermal decomposition during manufacturing. This extraction method reduces diffusible hydrogen in the weld metal without requiring CF4 addition to shielding gas, thereby maintaining arc stability and avoiding safety issues
4Reliability
If seamless flux cored wire is used to reduce hydrogen content, then diffusible hydrogen amount is reduced, but manufacturing cost increases significantly
Solution Approach 1:
Hydrogen sources are removed from the flux during the manufacturing process through high-temperature heating. This preliminary treatment allows the use of cost-effective seamed flux cored wire while achieving low hydrogen content in the weld metal, eliminating the need for expensive seamless wire construction
Solution Approach 2:
Hydrogen sources are extracted from the flux through thermal processing during manufacturing. This extraction method works effectively with seamed wire construction, allowing cost reduction while maintaining low diffusible hydrogen levels in the final weld product
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 significantly reduces the hydrogen content in weld metal, enabling efficient welding of high tensile strength steel and thick plates with good weldability and cost-effectiveness using seamed flux cored wires.
Implementation Method 1
a suction nozzle 216, arranged so as to surround a periphery of the contact tip 208 and extend beyond an end of the contact tip 208 in a longitudinal direction of the welding wire 201, the suction nozzle 216 being configured to suck out the diffusible hydrogen 212
Implementation Method 2
welding current flows from the contact tip 208 to the welding wire 201, and the welding wire 201 melts by an arc 209 at the tip end of the welding wire 201 to become a weld metal 210
Implementation Method 3
since the welding current flows through a wire protruding portion 211 of the welding wire 201 protruded from the contact tip 208, so that resistance heating occurs and the temperature rises
Implementation Method 4
Part of the hydrogen source 205 discharged from the welding wire 201 flows in the direction indicated by an arow 213 in accordance with the flow of shielding gas (in the direction indicated by an arrow 207) supplied to a welding part from a nozzle 206
Implementation Method 5
the hydrogen source 205, for example, H 2 O dissociates into diffusible hydrogen 212, is absorbed in droplets in the arc column and the weld metal 210, and enters the weld metal 210
Data Source
Figure 1A~1C
Figure 2A~2C
Figure 3
AI summary
Provided is a welding method using a special torch and a flux cored wire, in which the special torch has a suction nozzle between the contact tip and the shield nozzle, and the flux cored wire has a flux filled inside the steel outer casing, and a seam portion where both ends of a metal in a width direction of the steel outer casing are butted or overlapped in a longitudinal direction of the flux cored wire.