Suppression of Bottom Porosity in Fiber Laser Butt Welding of Stainless Steel

Xiaobing Pang,Jiahui Dai,Mingjun Zhang,Yan Zhang

doi:10.3390/photonics8090359

Abstract

The application bottleneck of laser welding is being gradually highlighted due to a high prevalence of porosity. Although laser welding technology has been well applied in fields such as vehicle body manufacturing, the suppression of weld porosity in the laser welding of stainless steel containers in the pharmaceutical industry is still challenging. The suppression of bottom porosity was investigated by applying ultrasonic vibration, changing welding positions and optimizing shielding gas in this paper. The results indicate that bottom porosities can be suppressed through application of ultrasonic vibration at an appropriate power. The keyhole in ultrasound-assisted laser welding is easier to penetrate, with better stability. No obvious bulge at the keyhole rear wall is found in vertical down welding, and the keyhole is much more stable than that in flat welding, thus eliminating bottom porosity. The top and bottom shielding gases achieve the minimal total porosities, without bottom porosity.

Highlights

304 austenitic stainless steel, due to its good corrosion resistance and mechanical properties, has been widely used in fields including pressure vessels and nuclear power equipment [1]
It is of great significance to suppress bottom porosities in laser welding of stainless steel for the application of laser welding technology in pharmaceutical container manufacturing
Lei et al [16] suggested that the porosity at the weld seam is greatly improved by the cavitation and acoustic streaming of the ultrasonic vibration on the weld pool in ultrasound-assisted laser welding of AZ31B magnesium alloy

Summary

Introduction

304 austenitic stainless steel, due to its good corrosion resistance and mechanical properties, has been widely used in fields including pressure vessels and nuclear power equipment [1]. It is of great significance to suppress bottom porosities in laser welding of stainless steel for the application of laser welding technology in pharmaceutical container manufacturing. That is, pulsed laser welding results in good stability of the keyhole and limits bubble formation by preventing shielding gas from being involved in the keyhole.

Results

Conclusion