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This work aimed to investigate the effect of the rotational speed of drilling pipe on casing wear using a laboratory-scale, pin-on-disc machine. The material used for the cylindrical pin specimens was type G105 steel, and the disc was made from type N80 carbon steel. Tests were conducted under simulated drilling fluid conditions. The wear rate, surface features, surface profile of the wear product films, composition of the wear product, and variations in drilling fluid temperature under different rotational speeds of drilling pipe were analyzed. Wear rate varied with increasing rotational speed of drilling pipe, but not in a linear manner. The reasons for the wear behaviour were explained in terms of a combination of abrasive wear, erosive wear, and corrosive wear. The activity of the Cl- in the drilling fluid could influence the formation and properties of the protective film on the casing surface. The results of this study could serve as a reference for drilling engineers, product suppliers, and manufacturers in related industries in reducing casing wear. [ABSTRACT FROM AUTHOR]

Centrifugal slurry pump is widely used for transportation of solids through pipeline in many chemical and mining industries. Erosion wear considered as one of the important parameter which plays significant role in slurry transportation system by affecting both initial cost and life of its components. In the present work, erosion wear due to solid–liquid mixture has been investigated using a slurry erosion pot tester. The erosion tests have been conducted on centrifugal slurry pump material stainless steel (SS304) to establish the influence of rotational speed, particle size, solid concentration and time duration. Sand and fly ash were taken as erodent materials with solid concentrations ranging from 30 to 60% (by weight). The experiments were performed at four different speeds namely 600, 900, 1200 and 1500 rpm with time duration of 90, 120, 150 and 180 minutes. WC–10Co–4Cr and Ni–20Cr 2 O 3 coating powders were used to increase the erosion wear resistance. Coating powders are deposited on pumping material by supersonic flame of high velocity oxygen fuel (HVOF) coating. Experimental results indicate that erosion wear has high dependence on rotational speed, time duration and nature of erodent solid particles. Significant improvement in erosion wear resistance was also observed by using WC–10Co–4Cr coating over Ni-20Cr 2 O 3 . [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the effects of rotational speed on rolling wear and damage behaviors of wheel/rail materials using a rolling–sliding wear testing apparatus. The results indicate that, with the rotational speed increasing, the surface hardness of rail roller remains unchanged while the increase of surface hardness of wheel roller declines resulting in a decrease of wheel/rail hardness ratio. The wear loss of wheel roller increases while the wear loss of rail roller declines with increasing rotational speed. The worn surface of rail roller exhibits peeling and spalling damage. Fatigue cracks and adhesive wear are dominating for the worn surface of wheel roller. Furthermore, with the speed increasing the fatigue damage lightens and adhesive wear worsens for the wheel roller. Fatigue cracks of wheel rollers grow along with soft ferrite lines in plastic deformation area. Cracks of rail rollers tend to turn towards the worn surface. There are visible branch cracks and multilayer cracks on the surface of wheel/rail rollers. Branch cracks of wheel rollers are longer than that of rail roller, and the interlayer material of multilayer cracks is easy to break. Wear debris of wheel/rail rollers is composed of Fe 2 O 3 and martensite. The size of debris with flakes structure decreases and the martensite content increases with the rotational speed increasing. [ABSTRACT FROM AUTHOR]

The D2 wheel steel rolling wear experiment was carried out on a double-disc wear test machine. By observing the polygonisation wear of the sample surface, measuring the vibration frequency, and analyzing sample microstructure and properties, the effects of rotational speed on the polygonisation formation mechanism, microstructure and property evolution of a D2 wheel steel were studied within a certain speed range. The results indicated that polygonisation wear was the result of the coupling of vibration and wear. The dominant vibration frequency (f) was constant at the three rotational speeds studied, and was equal to the product of the rotational speed (ω) and polygonisation order (K), that is, f = 1 60 K ω. When the number of rolling cycles was the same, the sample surface became subject to more times vibration and impact as the rotational speed decreased. This increased the intensity of the wear, and the polygonisation wear began to occur faster. Conversely, the polygonisation wear caused the vibration and impact load to increase, and the coupling effect of wear and vibration increased, further aggravating the polygonisation wear. After polygonisation wear occurred, the degree of crest oxidation wear was reduced in relation to the decreasing rotational speed. The degree of trough fatigue wear was also aggravated, causing the polygonisation wear gap to become larger, while the mass wearing quantity increased significantly given the same number of rolling cycles. The thickness of the obvious plastic deformation layer, the microstructure refinement, and the change in hardness of the surface layer all increased with the intensification of polygonisation wear. • F is constant at a certain speed range, and is equal to the product of ω and K. • The polygonisation wear appears faster as the rotational speed decreases. • The crest oxidative wear increases gradually, trough fatigue wear decreases. • The polygonisation gap become larger and the mass wearing quantity increases. • Microstructure refinement and hardness change of the surface layer all increase. [ABSTRACT FROM AUTHOR]