A New Solution for Wear and Corrosion Protection: Alternating Current GMAW with Nickel, Cobalt and Iron Basis Flux-Cored Hardfacing Wires


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Abstract
Several relevant industrial areas of emerging countries’ economic scenario, like oil drilling, agriculture and mining, rely on the hardfacing process to reach their procedure efficiency. The hardfacing technique consists on controlled deposition of materials with superior properties, like hardness, over parts made of inferior materials quality in these aspects. This deposited layer increases the corrosion and, specially, the abrasive wear resistance of the component. Although, the current welding processes used for hardfacing are either too costly or lack in deposit quality. Some applications, especially in the emerging countries that usually struggle with equipment investment, would use from this cost benefit gap filling. In this work, a welding procedure was develop aiming to fulfill this market need with a new solution. The goal was to use an advanced GMAW (Gas Metal Arc Welding) process, not as expensive as LASER and PTA, along with high quality consumables to reduce hardfacing global costs while assuring good metallurgical deposit quality. To solve this challenge the use of alternating current (AC) GMAW process by an OTC Welbee P400 power source and flux-cored wires was proposed. Deposits of three typical hardfacing flux-cored wires of Ni, Co and Fe basis were made over 1” thickness S235 construction steel bars and over 7” outer diameter steel pipes. ASTM G65 and G75 wear resistance tests were carried out to evaluate each deposit abrasive wear resistance. The results demonstrated high possibility for industrial success in the hardfacing area. With outstanding outcomes of deposition rates up to 10 kg/h with less than 10% of dilution rates, surpassing “cold processes” like Fronius CMT in quality and material loss in the deposition rate upper limit. The fused tungsten carbides (FTC) in the Ni basis wire deposition presented homogeneous distribution along the welding bead. This behavior is due to the better heat input control compared to conventional GMAW processes, permitting the FTC to remain integer throughout the material transfer. After the overlay on both bars and pipes it was demonstrated that this process variant is feasible for industrial manufacture and repairing. Although it’s metallurgical deposit quality still cannot match to PTA or LASER ones, the procedure here developed can fit the requirements of many vital applications, from hardfacing of sugarcane harvesting blades to oil drilling stabilizer tools, with reduced operational costs.
Key-words: Cladding, AC-MIG/MAG, Fused Tungsten Carbide, stellite, PTA

Referência
ROCHA , P. C. J.; SILVA, R. H. G.; SCHREIBER, F.; WILDEN, J.. A New Solution for Wear and Corrosion Protection: Alternating Current GMAW with Nickel, Cobalt and Iron Basis Flux-Cored Hardfacing Wires. XXXVIII CONSOLDA – Congresso Nacional de Soldagem, Setembro de 2018 - Uberlândia, MG, Brasil.