Henry Granjon Prize Competition 2006 Winner, Category D “Human related subjects” Method for Sampling and Characterizing Arc Welding Fume Particles

Abstract

Arc welding fume may pose a serious risk to the health and safety of welders and operators in the welding industry. Many methods have been employed to collect and characterize welding fume in the past but previous studies have often not used a combination of techniques that give the full picture on the nature of welding fume. This study was employed to collect fume generated by a variety of arc welding processes, including shielded metal arc welding (SMAW: E6010, E7018, E308–16) and gas metal arc welding (GMAW: ER70S-6 with 100% CO2 and 75% Ar-25% CO2 shielding gases), and to characterize the fume by size distribution, chemical composition, structure, and morphology with state-of-the-art techniques. This requires the use of multiple imaging and analysis techniques since the size variation of welding fume particles is quite large. Collection of welding fume generated by a variety of common electrodes was performed with an electrical low-pressure cascade impactor (ELPI) to size particles by their aerodynamic diameters and develop particle size distributions. A fume collection hood was also used to collect bulk fume samples and measure fume generation rates. Fume particles on the impactor stages were imaged using high resolution scanning electron microscopy (HR-SEM) and high resolution transmission electron microscopy (HR-TEM), revealing the presence of three fume particle morphologies including spherical, agglomerated, and irregular. TEM revealed the presence of a core-shell particle structure. Chemical analysis and phase identification was also performed for individual particles and bulk stages with energy dispersive X-ray spectroscopy (SEM-XEDS and TEM-XEDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Bulk fume and individual particles analyzed were largely metal-oxides with a Fe3O4-type crystal structure. Using these advanced characterization techniques in conjunction with one another provides an overall picture of fume that has been previously unattainable.