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Hardness and Impact Tests
Published in John Bird, Newnes Engineering Science Pocket Book, 2012
For materials of the same quality and for families of materials an approximate direct proportional relationship seems to exist between tensile strength and Brinell hardness number. For example, a nickel-chrome steel which is hardened and then tempered to various temperatures has tensile strengths varying from 1900 MPa to 1070 MPa as the Brinell hardness number varies from 530 to 300. A constant of proportionality k for: tensile strength = (k × hardness) in this case is 3.57 for all tempering temperatures. Similarly, for a family of carbon steels, the tensile strength varies from 380 MPa to 790 MPa as the carbon content increases. The Brinell hardness number varies from 115 to 230 over the same range of carbon values and the constant of proportionality in this case is 3.35. Because of the general approximate relationship between tensile strength and hardness, tables exist relating these quantities, the tables usually based on a constant of proportionality of about 3.35.
Pump Construction
Published in Ramnarayan Padmanabhan, Centrifugal Pump Clinic, 2017
When feedwaters are corrosive, cast iron seems to withstand the corrosion infinitely better than plain carbon steel. Chrome steels, however, with a chromium content of 5% or higher, withstand the action of any feedwater condition so far encountered. Some manufacturerss have a preference for 13% chrome steels for the impellers, wearing rings, and other pump parts other than the casing.
Tribological evaluation of PEG-based nanolubricants modified with graphene and copper oxide
Published in Journal of Dispersion Science and Technology, 2023
Mauricio Perez, Robison Buitrago-Sierra, Karen Cacua, Juan Santa
Four-ball were performed According to the ASTM D2783-08 standard.[31] In this test, one steel ball is rotating at 1770 ± 60 RPM against three steel balls which are fixed with a cup holder. In addition, the holder has 13 mL of lubricant that submerges the stationary balls. A series of test of 10 seconds duration was carried out. The steel balls were made of AISI 52100 chrome steel grade. The microhardness was 63.5 HRC and the roughness of the balls was 0.02 ± 0.01 µ. The load values might vary from 6 to 800 kgf according to the standard. In this article, the authors selected values from 63 kgf and the weld point was detected at 160 kgf. Each experiment was repeated twice under the same conditions, and the wear scar displayed is the mean value of each experiment. After the tests, the worn surfaces were analyzed by FE-SEM-EDS and the size of the wear scars was measured with a stereomicroscopy (Nikon SMZ1500). A summary of the methodology used in this article is shown in Figure 1.
Dry sliding wear of ductile and austempered ductile iron: effect of load and sliding speed
Published in Tribology - Materials, Surfaces & Interfaces, 2023
Shriya E, Manpreet Singh, Uma Batra, Sandan Kumar Sharma
Bearings are safety-critical components that work under severe conditions of high speed, large contact loads and high temperatures, such as in wind turbine gearboxes, automobiles or transmission gearboxes [1]. Majority of the failure of the bearing occurs due to extreme wear and lack of lubrication. Bearings along with its casings are usually manufactured by forging steels including low-carbon carburizing steel, medium-carbon steel or high-carbon bearing steels with chrome steel balls [2]. A wide variety of processes have been adopted to enhance the wear resistance of forged steels, such as nitrocarburizing, nitriding [3], carbide coatings [4], laser surface melting [2]. Usually, bearings are lubricated by employing low-friction lubricants to effectively reduce bearing friction [5]. However, poor lubricant selection, lubricant degradation, etc. can cause bearings fail catastrophically [6]. At lower loads and high speeds, bearings may also encounter skidding, leading to increased wear and reduced service life of the bearing. The use of solid lubricants like graphite is reported to reduce coefficients of friction [5]. Metal-based self-lubricating composites have also been suggested for the sliding parts because of their high strength and superior tribological properties [7].
Effects of Grinding Media on Grinding Products and Flotation Performance of Sulfide Ores
Published in Mineral Processing and Extractive Metallurgy Review, 2021
Xiaolong Zhang, Yuexin Han, S. K. Kawatra
A similar result was reported by Corin et al. (2018) who used four frequently-used grinding media (stainless steel rods, mild steel rods, 21% chrome steel balls, and forged steel balls) to grind a Cu-Ni base metal sulfide ore (Cu 0.36 wt%, Ni 0.67 wt%, S 5.67wt%). The lowest dissolved oxygen level of pulp was produced by grinding with mild steel rods. The reactivity of the media may have enhanced the galvanic interactions between grinding media and mineral and thereby promoted the reduction of the pulp oxygen. In contrast, relatively inactive media such as chrome steel balls produced the highest dissolved oxygen level. They also suggested that the dissolved oxygen concentration is a useful indicator of the chemical condition in the mill since the pulp potential is relatively strongly related to the dissolved oxygen concentrations, irrespective of the pH levels.