blog about Study Enhances S30408 Stainless Steel Laser Welds Via Coating

As industrial environments become increasingly demanding, improving the corrosion resistance and mechanical properties of stainless steel welded joints remains a critical challenge in materials science. This study focuses on S30408 austenitic stainless steel laser-welded joints, exploring effective methods to enhance their comprehensive performance through surface coating modification technology.

The research utilized 6mm-thick S30408 austenitic stainless steel plates as base material. Welding was performed using an RFL-C6000 laser system with argon gas (≥99.99% purity) as shielding gas. ER304 welding wire (Φ 1.2 mm) was selected, with its chemical composition detailed in Table 1.

To further improve joint performance, laser cladding (LC) technology was introduced using 90Co800–7SiC–3FeCrBSi (wt%) powder as coating material. The powder mixture consisted of Co800 (≥99.5% purity, 50–150 μm), SiC (≥99.5% purity, 50–150 μm), and FeCrBSi (≥99.5% purity, 100–150 μm) powders. The LC process employed an RFL-C3000 system with coaxial powder feeding.

Microstructural analysis was conducted using optical microscopy (MJF-100), scanning electron microscopy (SU3500) with EDS (XFlash6130), and high-resolution transmission electron microscopy (Titan 80–300). Electron backscatter diffraction (EBSD) was employed to analyze grain orientation, size, phase composition, and grain boundary characteristics. X-ray diffraction (D8 advance, Bruker) with Cu Kα radiation (2°/min scan rate, 10°–90° range) was used for phase analysis.

According to ASME standards, dog-bone shaped tensile specimens were prepared and tested at room temperature using an electronic universal testing machine (1 mm/min strain rate). Multiple tests ensured reliability, with SEM used to examine fracture morphology. Statistical analysis of tensile results evaluated key parameters including tensile strength, yield strength, and elongation.

A CHI760E electrochemical workstation tested corrosion behavior in 3.5 wt% NaCl solution. After stabilizing open-circuit potential for 400s, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were conducted. SEM, EDS, and Raman spectroscopy analyzed corrosion products to reveal mechanisms.

The Co800-SiC-FeCrBSi coating modification significantly improved both mechanical properties and corrosion resistance of S30408 laser-welded joints. The coating refined grain structure while serving as an effective barrier against corrosive media. Optimization of coating composition and processing parameters can further enhance performance for specific applications—such as marine environments requiring chloride resistance or high-temperature applications needing oxidation protection.

This study demonstrates that laser cladding with Co800-SiC-FeCrBSi coating effectively enhances the performance of S30408 austenitic stainless steel welded joints. The approach provides new solutions for applications in harsh environments, with future research directions including exploration of alternative coating materials and processing techniques.