Ultrasonic Narrow-Gap Welding for Uniform Microstructure and Fusion
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Solution Overview
Problem
Narrow-gap welding techniques face issues with uneven weld microstructure, severe porosity, and insufficient side wall fusion due to low heat input, which affects the quality and precision of high-strength steel welds.
Innovation Solution
An ultrasonic-stirring narrow gap welding system that incorporates an ultrasonic stirring subsystem with a stirrer inserted into the molten pool to enhance heat distribution and mechanical stirring, using an ultrasonic device with a transducer, amplitude transformer, and converter, to create a uniform microstructure and improve fusion quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If low heat input is used in narrow-gap GMAW, then overheat crispness and weakening of welded joint are reduced, but side-wall incomplete fusion defect is prone to occur
Solution Approach 1:
The patent applies ultrasonic vibration to the welding wire at a frequency of 20-100 kHz, causing the wire to vibrate mechanically as it enters the molten pool. This mechanical vibration enhances the stirring effect of the wire on the molten pool, improving side-wall fusion quality while maintaining low heat input conditions. The vibration energy directly transfers to the molten pool, creating micro-turbulence that promotes metallurgical bonding without requiring additional thermal energy.
2Productivity
If mechanical stirring is applied to improve side wall fusion, then welding efficiency is improved, but uneven temperature distribution in molten pool and large surface stress occur
Solution Approach 1:
The patent replaces mechanical stirring with ultrasonic vibration of the welding wire. The ultrasonic vibration creates gentle micro-turbulence in the molten pool through high-frequency oscillations, which promotes uniform temperature distribution and reduces surface stress. Unlike mechanical stirring that creates large-scale fluid motion and stress concentration, ultrasonic vibration distributes energy uniformly throughout the molten pool volume, achieving both efficient welding and homogeneous microstructure.
Solution Approach 2:
The patent changes the operating parameters by introducing ultrasonic vibration frequency (20-100 kHz) and amplitude control. By adjusting these parameters, the system optimizes the stirring effect while maintaining temperature uniformity. The high-frequency low-amplitude vibration creates sufficient mixing without the large-scale thermal gradients and stress concentrations associated with mechanical stirring methods.
3Reliability
If strong mechanical stirring is applied, then side wall fusion quality is improved, but weld microstructure becomes uneven and welding precision requirement is difficult to meet
Solution Approach 1:
The patent employs ultrasonic vibration of the welding wire to achieve side-wall fusion without the microstructure defects caused by mechanical stirring. The ultrasonic vibration frequency (20-100 kHz) creates fine-scale mixing that promotes uniform grain structure formation. The high-frequency oscillations break up large dendritic structures and promote equiaxed grain formation, resulting in homogeneous weld microstructure while ensuring complete side-wall fusion.
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 system achieves uniform heat distribution, reduced porosity, and improved side wall penetration, resulting in high-quality welds with enhanced toughness and precision, while maintaining low heat input and being cost-effective and adaptable for industrial applications.
Implementation Method 1
the ultrasonic device includes an ultrasonic vibration power source, a transducer, an amplitude transformer, and a converter which are sequentially connected
Implementation Method 2
a positive pole of the welding machine power source is connected with the welding wire in the narrow gap welding torch, and a negative pole of the welding machine power source is connected with the to-be-welded workpiece
Data Source
AI summary
An ultrasonic-stirring narrow gap welding system and a welding method, and the ultrasonic-stirring narrow gap welding system includes a welding machine power source, a wire feeder, a narrow gap welding torch, and an ultrasonic stirring subsystem. A welding wire is fed into a narrow gap through the narrow gap welding torch provided above a groove, to generate an arc for welding. The ultrasonic stirring subsystem includes a stirrer and an ultrasonic device, a stirring rod is connected to the ultrasonic device and inserted into a molten pool to form a preset angle relative to the welding wire for stirring, and an ultrasonic-stirring narrow gap welding mode is realized.