Application Cases

[Overview]

In this study, a high-voltage power amplifier was used to build a GTAW self-induced ultrasonic welding experimental platform. The feasibility and effectiveness of the arc self-induced ultrasonic process were verified, and the influence of different ultrasonic excitation frequencies on the penetration depth, fusion width, and microstructure of AISI 316 stainless steel weld overlay was investigated.

Experiment Name: Experiment on the Effectiveness of GTAW Self-Induced Ultrasonic Process in Forming and Microstructure Regulation of AISI 316 Stainless Steel Weld Overlay

Research Directions: GTAW; self-induced ultrasound; AISI 316 stainless steel; weld overlay; microstructure; grain refinement; molten pool morphology; weld geometry regulation.

Experiment Objective: This experiment aims to build a GTAW self-induced ultrasonic welding experimental platform, verify the feasibility and effectiveness of the arc self-induced ultrasonic process, investigate the influence of different ultrasonic excitation frequencies on the penetration depth, fusion width, and microstructure of the AISI 316 stainless steel weld overlay, determine the optimal ultrasonic process parameters, and reveal the intrinsic mechanism of molten pool evolution and grain refinement under ultrasonic action.

Test Equipment:

1. Self-built GTAW self-induced ultrasonic welding platform (DC power supply, power amplifier, data acquisition card)

2. Hall current sensor

3. Ultrasonic sensor

4. High-frequency acoustic-field pressure sensor

5. High-speed camera with narrowband filter

6. Oscilloscope

7. Industrial computer

8. NOVA 230 scanning electron microscope (SEM), Leica Z16 APO macro microscope, Nikon LV150N optical microscope

9. EBSD detection system

10. Water chiller and water-cooling plate

Figure 1. Schematic of the experimental platform

Experiment Procedure:

Using ER316L welding wire as filler material and 316L stainless steel as the substrate, five ultrasonic excitation frequencies (0, 20, 40, 60, 80 kHz) were set via LabVIEW, while basic process parameters such as welding current were kept constant to carry out overlay welding experiments. A high-speed camera was used to observe the arc morphology, and an acoustic pressure sensor monitored the sound-pressure signal of the arc self-induced ultrasound. After mechanical polishing and electrolytic polishing of the overlay samples, SEM, EBSD, and other equipment were used to analyze the molten pool morphology, weld dimensions, and microstructure, and key data such as penetration depth, fusion width, and grain size were statistically evaluated.

Experiment Results:

The built GTAW self-induced ultrasonic welding platform can effectively excite ultrasound; arc morphology and sound-pressure tests fully verified the process effectiveness. At an ultrasonic excitation frequency of 60 kHz, the weld penetration depth increased by 59.67% and the fusion width decreased by 30.14%. The 40–60 kHz range is close to the natural frequency of the AISI 316 stainless steel overlay molten-pool system, giving the best grain-refinement effect: the average grain size was reduced by up to 24.4%, columnar crystals were significantly refined, and the proportion of equiaxed dendritic crystals increased. When the frequency was raised to 80 kHz, the refinement and penetration-enhancement effects slightly weakened.

Product Advantages of Aigtek Amplifiers in This Application:

1. Wide-band sweep-frequency coverage — Precisely matches the full-frequency-range process exploration requirements.

2. High-stable power output — Ensures the penetration-depth experimental effect of the weld.

3. Low-distortion output and high reliability — Supports accurate verification of grain refinement near the natural-frequency range.

[Recommended Product]: ATA-4000 Series High-Voltage Power Amplifier

Figure: Specifications of the ATA-4000 series high-voltage power amplifier

The experimental materials in this article were compiled and published by Xi'an Aigtek Electronics. Aigtek has become an instrumentation supplier with a broad product portfolio and considerable scale in the industry; demonstration units are available with free trial support. Xi'an Aigtek Electronics is a high-tech enterprise specializing in the R&D, manufacturing, and sales of electronic test instruments including power amplifiers, high-voltage amplifiers, power signal sources, preamplifiers (low-noise signal amplifiers), high-precision voltage sources, and high-precision current sources.