Study the Effect of Twin Wire Arc Spraying Parameters on Surface Properties of Stainless Steel

Abstract

Wire arc spraying is a widely used and cost-effective thermal spray technique that utilizes two metal wires fed into an electric arc. This study addresses a practical industrial issue observed at the Basra Refinery under the Ministry of Oil, where shafts of rotating and stationary equipment particularly at bearing contact zones suffer from frequent damage due to friction and wear. Traditional repair methods, including welding, have shown limited effectiveness, often resulting in distortion and degradation of mechanical properties caused by excessive heat exposure.As an alternative, this research explores the use of twin wire arc spraying to enhance the surface integrity and wear resistance of stainless steel components. The coating process was performed using the Arc Spray System Model BP400, manufactured by TAFA. Stainless steel 304 was selected as the substrate, coated with 55T-18/5 stainless wire (200 series), 1.6 mm in diameter. The study investigates the influence of key process parameters, particularly the spray distance, on the coating’s surface characteristics. Spray distances of 10, 15, 20, and 30 cm were evaluated, while other parameters were fixed: 90° spray angle, 3.8 bar air pressure, 39 ±1 V, 124 ±1 A, and a spraying duration of approximately 30 ±5 seconds. Experimental evaluation focused on surface roughness, coating thickness, adhesion strength, microstructure (via SEM and optical microscopy), wear resistance, and Vickers hardness. The results showed that a spray distance of 15 cm yielded the best performance: hardness increased from 176.8 HV (substrate) to 367 HV, representing a 107% improvement. Additionally, the wear rate reached its lowest value at 15 cm (2.4 × 10⁻⁸ g/cm) indicating superior durability. At the same distance, the highest adhesion strength of 14.14 MPa (2051 psi) was recorded. These findings confirm that optimizing spray parameters particularly the spray distance can significantly improve the mechanical performance and service life of coated stainless steel components, providing an effective solution for industrial repair and surface enhancement in demanding environments.