| Abstract Scope |
Steel bridges will often use protective coatings such as paint, hot-dip galvanizing , and thermal-spray metallizing to protect the material from the environment. Historically, welding on these coatings have led to issues such as weld cracking, workplace pollution, damage to the surface appearance, and blowholes in the weld metal among other issues.
This presentation will cover the findings of a study aimed at developing acceptable welds on thermal-spray metallized and hot-dip galvanized coatings on ASTM A709, grade 50 steel. Specific objectives of this study were (1) to compare weld quality of flux-cored arc welded joints on zinc-coated steel to those on uncoated steel, (2) to evaluate the effect of coating type and thickness on weld quality, (3) to evaluate the mechanical properties of welds on zinc-coated steel containing defects, (4) to evaluate the propensity for zinc penetration cracking, and (5) to identify limitations and/or specific requirements for welding over protective coatings that would be required to produce acceptable welds. The quality of welds was determined based on visual examination, ultrasonic testing, radiographic testing, and macroetch specimens.
This presentation will conclude with the current findings of this study and recommendations for welding on zinc-coated steel. |