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Comparison of the performance properties of commercially produced roller cone bit coatings

Koczkodaj Sylwia, Mizera Jarosław, Moszczynska Dorota, Zdunek Joanna, Plocinska Magdalena, Szpyrka Jacek, Burkot Marek, Szpak Mateusz

Materials Science Poland

2023

Vol. 41, No. 1

110-123

This paper studies the material aspects of roller cone bits with milled teeth. The research concerns the properties of commercial product overlays provided by the company Glinik Drilling Tools. The analyzed coatings were produced according to the company’s procedures using two surfacing methods: gas welding and plasma transferred arc (PTA) welding. Metallographic observations and chemical composition analyses were carried out. The evaluation criteria in the context of the surfacing application were mechanical properties: hardness, impact strength, and abrasion resistance. The overlays produced by gas welding were characterized by lower hardness, impact strength, and abrasion resistance. The study showed that it differed from the deposit made by the PTA method in the matrix material and in the average size of the tungsten carbides. The dissolution of primary carbides and formation of secondary carbides such as Fe3C and Ni17W3 were found to occur in both surfacing types. This contributes to the increased brittleness of the matrix and reduced wear resistance of the materials.

Hardfacing of mild steel with wear-resistant Ni-based powders containing WC particles using PPTAW technology

Appiah Augustine, Bialas Oktawian, Jędrzejczyk Marcelina, Ciemała Natalia, Wantuch Łucja, Żuk Marcin, Czupryński Artur, Adamiak Marcin

Welding Technology Review

2022

R. 94

3--18

This study explores the use of powder plasma transferred arc welding (PPTAW) as a surface layers deposition technology to form hardfaced coatings to improve upon the wear resistance of mild steel. Hardfaced layers/coatings were prepared using the PPTAW process with two different wear-resistant powders: PG 6503 (NiSiB+60% WC) and PE 8214 (NiCrSiB+45% WC). By varying the PPTAW process parameters of plasma gas flow rate (PGFR) and plasma arc current, hardfaced layers were prepared. Microscopic examinations were carried out to investigate the microstructure and surface characteristics of the prepared hardfaced layers. Penetration tests were performed to ascertain the number and depth of crack sites in the prepared samples by visual inspection. The hardness of the hardfaced layers were determined: hardfacings prepared with PG 6503 had hardness of 46.3 - 48.3 HRC, those prepared with PE 8214 had hardness of 52.7 - 58.3 HRC. The microhardness of the matrix material was in the range of 573.3 - 893.0 HV, and the carbides had microhardness in the range of 2128.7 - 2436.3 HV. Abrasive wear resistance tests were carried out on each prepared sample to determine their relative abrasive wear resistance relative to the reference material, abrasion resistant heat-treated steel, Hardox 400, having a nominal hardness of approximately 400 HV. Findings from the research showed that the wear resistance of the mild steel was improved after deposition of hardfaced layers; the hardness and wear resistance were increased upon addition of Cr as an alloying element; increasing the PGFR increased the hardness and wear resistance of the hardfacings, as well as increase in the number of cracks; increasing the PTA current resulted in hardfacings with less cracks, but relatively lowered the wear resistance. The wear mechanisms were discussed.