Ring mode laser eliminates spatter during aluminum alloy welding.

01 Paper Introduction

Due to the high reflectivity and thermal conductivity of aluminum alloys, traditional laser welding often leads to excessive energy density and unstable keyholes, resulting in spattering that negatively affects weld quality and component performance.
Through experiments—by setting different total laser powers, core/ring power ratios, and welding speeds, observing vapor plume and spatter dynamics via a high-speed camera, and analyzing weld morphology using a super-depth microscope—combined with three-dimensional transient multiphysics coupled numerical simulations, this study reveals the core mechanism by which ring-shaped lasers preheat the leading edge of the molten pool, reduce fluctuations in laser absorptivity, and stabilize vapor plume ejection to suppress spattering.
A quantitative correlation model between preheating temperature and total power, ring power ratio, and welding speed is established, proposing that the preheating temperature should be within the effective range between the melting point and boiling point of the base material. Furthermore, a parameter selection criterion for spatter-free processing is derived and experimentally verified, providing theoretical and industrial guidance for achieving high-quality laser welding of high-reflectivity alloys.

02 Full Text Overview

This paper combines experiments and three-dimensional transient multiphysics coupled numerical simulations. Using 6061 aluminum alloy plates as the experimental subject, six core/ring power ratios (10:0 to 0:10), three welding speeds (40 mm/s, 60 mm/s, and 80 mm/s), and a fixed total laser power of 6000 W were set. The vapor plume and spatter were observed using a high-speed camera, and weld morphology was analyzed with a super-depth microscope. A comparative experiment with fixed core power was also designed. The numerical simulation used a CFD model to simulate thermal flow fields and laser absorption processes in the molten pool.
Experimental results show that as the proportion of ring laser power increases, the weld surface becomes more uniform (the peak-valley difference decreases from 1.40 mm to 0.41 mm), and the spatter frequency decreases by 65%. The study further reveals that the ring laser preheats the leading edge of the molten pool, narrows the range of absorptivity fluctuations, and stabilizes the vapor plume, thereby suppressing spattering. Finally, a quantitative model between preheating temperature and process parameters is established, defining the effective range between the melting and boiling points of the base material, and deriving and verifying a spatter-free process criterion, providing theoretical guidance for spatter-free laser welding of aluminum alloys.

03 Figures and Analysis

Figure 1 conveys two key aspects:
(1) Figure 1(a) presents the core hardware configuration of the adjustable ring-mode laser welding setup, including the CFX-8000 programmable fiber laser, robot, laser processing head, and high-speed camera, clarifying the system logic and ensuring standardized operation and data collection.
(2) Figure 1(b) visualizes the key physical phenomena during laser welding—such as phase change, laser absorption, and vapor dynamics—constructing a physical framework for laser–material interaction that provides a theoretical basis for three-dimensional transient multiphysics coupled simulation and helps understand the underlying mechanism of spatter formation.

Figure 1. Schematic diagram of the welding system and statistical diagram of physical phenomena: (a) Schematic diagram of the experimental setup; (b) Schematic diagram of physical phenomena.

Figure 2 reflects the correlation between process parameters and weld morphology in adjustable ring-mode laser welding (ARM-LW).

• Figure 2(a) shows 18 sets of weld surfaces under a total laser power of 6000 W, varying core/ring power ratios (10:0 to 0:10) and welding speeds (40–80 mm/s), with color-coded quality levels that intuitively indicate reduced spatter and improved weld formation after adding the ring laser.

• Figure 2(b) presents the process window of core/ring power ratio versus welding speed, highlighting the “good formation region,” which expands significantly under ARM-LW conditions.

Figure 2. Weld formation and process window diagrams under different process parameters: (a) Weld surface morphology; (b) Core/ring power ratio - welding speed process window.

Figure 3 (at a fixed welding speed of 80 mm/s) shows weld characteristics under different core/ring power ratios.

• Figures 3(a)(c)(e) display the 3D surface profiles of welds at ratios of 10:0, 6:4, and 0:10, where peak-valley data quantify surface improvement due to reduced spatter.

• Figures 3(b)(d)(f) show the corresponding cross-sections with fusion width labeled, revealing that ring-mode lasers increase fusion width and bridging ability, highlighting their influence on cross-sectional geometry.

• Figure 3(g) compares longitudinal weld height variations along the welding direction for three ratios, complementing the surface morphology analysis.

Figure 3. Weld contour and cross-sectional diagrams under different core/ring power ratios: (a)(c)(e) Weld surface contour and line height diagrams; (b)(d)(f) Weld cross-sectional diagrams; (g) Weld longitudinal section.

Figure 4 compares the molten pool temperature characteristics between adjustable ring-mode laser welding (ARM-LW) and traditional laser welding (LW).

• Figure 4(a) shows that the front temperature gradient of the ARM-LW molten pool is smoother, with a larger area in the 564–644 K range and a wider keyhole entrance, intuitively demonstrating the thermal regulation of ring lasers.

• Figure 4(b) presents temperature variations along a linear segment (z = +0.04 mm), where ARM-LW exhibits a distinct preheating peak at the front weld area, a significantly smaller temperature gradient, and a more stable keyhole, quantitatively confirming the preheating and stabilizing effects of the ring laser.

Figure 4. Temperature field and thermal cycle curve of the molten pool: (a) Temperature cloud map of the molten pool surface; (b) Thermal cycle curve of the longitudinal section of the molten pool.

04 Conclusion

This study focuses on the spattering phenomenon in aluminum alloy adjustable ring-mode laser welding. Through experiments (with varying core/ring power ratios and welding speeds, combined with high-speed camera and super-depth microscopy observations) and three-dimensional transient multiphysics coupled numerical simulations, it reveals that ring lasers suppress spattering by preheating the leading edge of the molten pool, narrowing absorptivity fluctuations, and stabilizing vapor plume dynamics.
A quantitative model between preheating temperature and process parameters is established, confirming that the preheating temperature must lie between the melting and boiling points of the base material. The spatter-free process criterion was derived and experimentally validated, providing a defined parameter range for spatter-free welding. This study offers theoretical guidance for industries such as automotive manufacturing that rely on lightweight aluminum alloy components, addressing issues of excessive spattering and poor weld quality in traditional laser welding, and promoting the industrialization of high-quality, high-stability aluminum alloy laser welding.

**--Cite the article published by 高能束加工技术 on November 4, 2025, in the WeChat public account "High-Energy Beam Processing Technology and Applications."