Repair/strengthening of steel angles using thermal spray metallizing

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Leong, Chuen Shiong
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Corrosion of steel structures has been a serious problem in civil engineering for years. Repairing such structures is becomi g increasingly important to maintain the integrity of corroded structures for public safety. In recent years, many studies have been conducted on the use of thermal spray metallizing coatings on metallic substrates. This technique is widely used for corrosion and wearing protection. In this research program, the effectiveness of the thermal spray metallizing technique was examined as a means of repairing corroded steel structures. The spray material used to replace the corroded material on steel sections was produced through the thermal spray process. Determining the mechanical properties of thick spray coatings was a fundamental prerequisite in evaluating the effectiveness of this technique. Spray materials included Zinc, Aluminum, Zn85 Al15 alloy, 10-carbon steel (CSA standard W48.4-1978, class E70s-6) and 40-carbon steel applied on a series of specimens which were tested under static tension and compression. Based on the results from these tests, 10-carbon steel and 40-carbon steel were selected as the repair materials for defective steel angles. Two sets of seven L76 x 76 x 4.8 steel angle specimens were repaired and tested under static compression. In addition, seven steel plate specimens repaired with 10-carbon steel were tested in tension. The 10-carbon steel performed better and improved the strength of repaired specimens in compression compared to 40-carbon steel. Although the repair material exhibited low tensile and bond strengths, they improved the compressive buckling strength of repaired specimens by 89% to 97%. However, steel plates repaired with 10-carbon steel showed no improvement in strength under tension. In addition, to the experimental work, extensive theoretical analysis using the finite element program ANSYS was also conducted. The finite element results agreed well with the experimental results.