Relevance of Laboratory Wear Experiments for the Evaluation of In-Service Performance of Materials

In high-stress abrasion, rocks or minerals are being crushed between two moving bodies. In the mining industry, this kind of wear occurs for example in the haulage and grinding of minerals. Wear of materials causes also significant economic and ecological losses in the mining business, because the replacement of wear parts causes interruptions in the mining operations, and production of new wear parts creates a big carbon footprint for the mines. Therefore, the selection and development of better materials for the demanding wear environments is worth the effort.Although the results of field wear tests are readily applicable for example for materials selection, such tests are challenging to conduct, overly expensive, and very time consuming. Thus, it is important to create substitutive application oriented wear test methods and research methodologies that produce relevant and repeatable results and are well controllable, unlike the in-service conditions. However, the relevance of the test method should also be somehow traceable and verifiable.This thesis elucidates the relevance of laboratory wear experiments for the evaluation of the in-service performance of materials. Two cutting edges of underground mining loader buckets and two feed hopper wear plates were tested in the in-service conditions, and their wear rates were recorded using 3D scanning. Moreover, a used wear plate of a dumper truck body and a grooved roller from a hoist system were received for characterization. A novel method for testing impact wear of steels in Arctic conditions was also used and analyzed. The wear conditions in these in-service cases were simulated using various laboratory wear testing systems, the wear surfaces and cross-sections of the test specimens were carefully characterized, and the results of the wear tests and characterizations were correlated with the in-service cases.There are two common ways to utilize laboratory wear tests, i.e., testing of different materials using the same test method or device, or testing the same material(s) using different test methods. In both cases, however, the fundamental question is, how do the test results compare with the real application under consideration? Another question that affects the outcome of the testing program is, how should the test results be presented to obtain the correct or best possible answer to the set research question? In this work, normalization of the test results using the mass loss of a reference sample proved to be a good methodology, when comparing the wear rates of different steels. Even the small differences between the different test cycles were corrected in this way. However, when different test methods are compared to each other or to the in-service data, the normalization should also take account of the differences in the contact time and the contact area in different cases. In addition to the numerical correlation, it is essential to characterize and compare the wear mechanisms and deformation of materials during wear. Only by combing these two different types of results, the relevance of the used test method can be assessed and confirmed

Systems dynamic model of wear evolution for sheaves used in oil and gas hoisting operations

The global offshore drilling contracted fleet consisted of 378 jack-ups, 68 semisubmersibles and 73 drillships, according to Westwood Global Energy Group, as of September 2023. In most regions of the world, rig activity has picked up from increased operator demand and pushed the marketed utilization for jack-ups from 76% to 85%, semis from 60% to 80% and drillships from 82% to 90%. The utilization of a drilling rig depends on various factors, mainly drilling demand, rig capability and specifications, and rig efficiency and reliability. Worn sheave grooves can pull down the efficiency of a drive by 8% accelerate the wearing of ropes reduce rope life, increase maintenance costs, and the need for more frequent rope replacements. Wear depth for sheaves is typically measured as the depth of wear in the groove of the sheave, which indicates the extent to which the sheave has worn down over time. Research on surface wear of wire rope caused by the contact between the wire rope and the sheave has rarely been carried out. Upgrading Archard's Wear model is needed to provide a better estimation of wear depth for sheaves. Moreover, the wear coefficient shall be determined. Therefore, the purpose of this paper is to model the wear evolution caused by the sliding contact between the wire rope and the sheave. To achieve this purpose, case sheaves were purposefully selected, studied and modelled using both the analytical and simulation modelling approaches.publishedVersio

Mechanisms of Oxidation Degradation of Cr12 Roller Steel during Thermal Fatigue Tests

Degradation by the penetration of oxidation into the Cr12 roller steel is evaluated during thermal fatigue tests in the laboratory in the temperature range of 500–700 °C. A qualitative assessment is carried out with regard to the thermal load, the microstructure and the test temperature. The results show that the specific properties of the microstructure with respect to thermal stress and temperature have a significant influence on the oxidation behavior as well as on the crack propagation mode and crack growth. The conditions that lead to an increase in the oxidation rate and thus to premature and sudden local chipping of the roll surface layer are analyzed and explained.</jats:p

Book of abstracts of the 15th International Symposium of Croatian Metallurgical Society - SHMD \u272022, Materials and metallurgy

Book of abstracts of the 15th International Symposium of Croatian Metallurgical Society - SHMD \u272022, Materials and metallurgy, Zagreb, Croatia, March 22-23, 2022. Abstracts are organized in four sections: Materials - section A; Process metallurgy - Section B; Plastic processing - Section C and Metallurgy and related topics - Section D

Book of abstracts of the 15th International Symposium of Croatian Metallurgical Society - SHMD \u272022, Materials and metallurgy

Book of abstracts of the 15th International Symposium of Croatian Metallurgical Society - SHMD \u272022, Materials and metallurgy, Zagreb, Croatia, March 22-23, 2022. Abstracts are organized in four sections: Materials - section A; Process metallurgy - Section B; Plastic processing - Section C and Metallurgy and related topics - Section D

Metalurgija Journal 1962-2022 y – List of Published Papers

U periodu 1962.–2012., tijekom 60 godina neprekidnog izlaženja, u časopisu Metalurgija su objavljivali autori iz preko 40 država, od Mexica do Kine (sa svih 5 kontinenata). Cilj članka je dati Listu objavljenih radova u 199 svezaka ili 238 brojeva, sa 2721 znanstvenih i stručnih, te 287 priloga (ukupno 3008 radova), autora, koji su svoje rezultate i ideje provjeravali ili ih našli na stranicama ovog časopisa. Svima hvala.For the interval 1962-2022 y, during the continuos publication last 60 years, in Metalurgija Journal Authors from 40 countries from Mexico to China (all 5 continent ) have publish. The goal of the Article is give List of Papers published in this interval, 199 issues or 238 numbers, 2721 scientific and technical, and 287 contributions (total 3008 papers ) of Authors whose investigation results and ideas have been examined and found on the pages of this Journal. Thanks for all

Metalurgija Journal 1962-2022 y – List of Published Papers

U periodu 1962.–2012., tijekom 60 godina neprekidnog izlaženja, u časopisu Metalurgija su objavljivali autori iz preko 40 država, od Mexica do Kine (sa svih 5 kontinenata). Cilj članka je dati Listu objavljenih radova u 199 svezaka ili 238 brojeva, sa 2721 znanstvenih i stručnih, te 287 priloga (ukupno 3008 radova), autora, koji su svoje rezultate i ideje provjeravali ili ih našli na stranicama ovog časopisa. Svima hvala.For the interval 1962-2022 y, during the continuos publication last 60 years, in Metalurgija Journal Authors from 40 countries from Mexico to China (all 5 continent ) have publish. The goal of the Article is give List of Papers published in this interval, 199 issues or 238 numbers, 2721 scientific and technical, and 287 contributions (total 3008 papers ) of Authors whose investigation results and ideas have been examined and found on the pages of this Journal. Thanks for all

The 31st Aerospace Mechanisms Symposium

The proceedings of the 31st Aerospace Mechanisms Symposium are reported. Topics covered include: robotics, deployment mechanisms, bearings, actuators, scanners, boom and antenna release, and test equipment. A major focus is the reporting of problems and solutions associated with the development and flight certification of new mechanisms