Research methods for the evaluation of the relevance of application oriented laboratory wear tests

In this work, different research methods and test procedures were examined and compared in order to have a better understanding of the relevance of various application oriented laboratory wear tests relative to the in-service performance of the steels in mining conditions. One of the important results of this study is that quite different wear events can be compared, when the wear rates are presented as the mass loss of the sample divided by the wear area, contact time, and density of the material. However, this kind of information is commonly very difficult to obtain for the in-service samples, and thus normalizing of the results with a reference material is often an easier route. On the other hand, thorough characterization and comparison of the wear surfaces and deformations is essential for the confirmation of the similarity of the wear mechanisms in different cases or different tests. In the studied case of the wear plate of a dumper truck body, several test methods were needed for the experimental simulation of the complex wear environment in the haulage of minerals

High speed slurry-pot erosion wear testing with large abrasive particles

One of the testing methods used to simulate slurry erosion in laboratory conditions is the slurry-pot method. In this work, a novel high speed slurry-pot type erosion wear tester was constructed for testing of materials used in mining and other mineral handling applications. In the tester, the samples are attached to a vertical rotating shaft on four levels in a pin mill configuration. High speeds up to 20 m/s at the sample tip can be achieved also with large abrasive size up to 10 mm. In the tests, the equipment proved to be functional and durable even with the high loads created by the high speeds and large abrasive sizes. There are, however, variations in the slurry concentrations inside the pot during testing, leading to different wear rates at the different sample levels. Therefore, a sample rotation test method was developed. By rotating the samples evenly through all sample levels, the overall deviations between samples will be minimized. Furthermore, with the sample rotation method up to eight materials can be tested simultaneously. The slurry-pot is suitable for testing various materials, such as steels and rubbers

Effect of abrasive properties on the high-stress three-body abrasion of steels and hard metals

Especially in tunneling, the abrasiveness of rock is an important property, which can easily be determined by several methods developed for the purpose. With this in mind, it is rather surprising that the effects of different rock types on the wear mechanisms of engineering materials have not been too widely studied. In this paper, high stress three-body abrasive tests were conducted with four different abrasives with a relatively large (2-10 mm) particle size. As test materials, three different steels and three hard metals were used. The tests clearly showed that material type has an influence on how different abrasive and material properties affect the abrasive wear mechanisms and severity. For example with hard metals, the most important property of the abrasives is their crushability, as only small abrasive particles are able to properly attack the binder phase and cause high wear rates. On the other hand, it seems that the abrasiveness of rock is not the dominating property determining the severity of wear in the current test conditions for any of the tested materials. In fact, with steels no single abrasive property could be shown to clearly govern the abrasive wear processes. In any case, when using the determined abrasiveness values in wear estimations, the contact conditions in the method used for determining the abrasiveness values should be as similar as possible with the end application

Compressive crushing of granite with wear-resistant materials

Uniaxial crusher is a non-standard wear testing device designed and used at the Tampere Wear Center for evaluating the wear resistance of materials in compressive crushing. In this study, various wear resistant materials were tested and their wear surfaces characterized with scanning electron microscopy. In addition, the general suitability of the device for wear testing was evaluated. Abrasive wear was the most common wear mechanism observed on the studied surfaces. Moreover, marks of surface fatigue were also seen. The material loss was mostly due to plastic deformation. Higher hardness was found to correlate with improved wear resistance, especially in cases where wear was purely abrasive

Impact-abrasive and abrasive wear behavior of low carbon steels with a range of hardness-toughness properties

This work investigates steels for mining wear applications involving abrasive and impact-abrasive conditions. The study comprises four low carbon steels with a range of hardness-toughness combinations: a commercial grade martensitic steel, the same steel heat treated to lower bainite, a commercial TRIP steel (tensile strength grade 700 MPa), and a quenching-partitioning (QP) steel. The steels were subjected to crushing pin-on-disc (CPOD) and slurry-pot wear tests, offering reasonably high-stress abrasive and impact-abrasive conditions, respectively. The results showed that the best performer in both studied wear conditions is the martensitic steel due to its higher initial hardness. Nevertheless, the performance benefit of this steel was of lesser magnitude in the slurry-pot than in the CPOD tests. On the other hand, the TRIP steel showed poor ranking in the CPOD tests but outperformed the QP and lower bainite steels in the slurry-pot tests. Detailed surface and subsurface wear damage investigations were conducted to study the wear responses of the microstructural constituents of the steels to explain their wear behavior in different wear conditions.acceptedVersionPeer reviewe

Tekoäly, koneoppiminen ja teknologinen murros:: Kohti datatoimijuutta ja tulevaisuuden design-taitoja

Tekoälyn ja erityisesti uudet koneoppimisen tekniikat ovat teknologisen murroksen keskeisiä ajureita. Tänä päivänä koneoppiminen on myös yhä enemmän sulautumassa osaksi kehollista ja materiaalista maailmaa sekä vuorovaikutusta. Antureiden, verkkoyhteyksien ja tietokoneohjelmistojen kautta rakennukset, esineet ja tekstiilit ovat muuttumassa älykkäiden esineiden ja toimintojen verkostoiksi. Virtuaalisen, materiaalisen ja kehollisuuden uudenlainen kohtaaminen tarjoaa myös ennennäkemättömiä mahdollisuuksia sekä haasteita koneoppimisen sekä datalähtöisen suunnittelun ja innovoinnin tukemiseen kouluopetuksessa. Tämän artikkelin tavoitteena on rakentaa näkökulmia datatoimijuuteen sekä datalähtöiseen design-ajatteluun koneoppimisen muovaamassa maailmassa.  Artikkeli esittelee digitaalisen, materiaalisen sekä kehollisuuden uudenlaisia mahdollisuuksia sekä riskejä, joka tuo koneoppimisen ajamaan murrokseen liittyviä näkökulmia osaksi käsityön ja teknologiakasvatuksen tulevaisuudesta käytävää tieteellistä ja julkista keskustelua.   Artificial intelligence, machine learning, and technological transformation: Towards data agency and design skills for the future Abstract Artificial intelligence, and especially new machine learning technologies, are key drivers of technological breakthroughs. Today, machine learning is also increasingly merging into the physical and material world as well as into social interaction. Buildings, artifacts, and textiles are transforming into networks of smart objects and activities through sensors, network connectivity, and computer software.  These novel encounters of virtual, material, and bodily interactions also offer unprecedented opportunities and challenges to enhance understandings of machine learning and data-driven design in school education. This article aims to build perspectives on data agency and data-driven design needed in the age of machine learning. It also provides perspectives on the blurring boundaries of virtual, material, and physical worlds and in a manner that brings the breakthrough of machine learning into the scientific and public discussion about the future of craft and technology education. Keywords: artificial intelligence, machine learning, data-driven design, technology education, skills for the futur

High-stress abrasion of wear resistant steels in the cutting edges of loader buckets

To simulate the wear behavior of the cutting edge of the mining load-haul-dumper bucket, high-stress abrasion laboratory wear tests were conducted and compared to the in-service tests. The effects of test parameters and different abrasives on the wear rates and wear mechanisms of wear resistant steels were studied using the high-speed slurry-pot with a dry abrasive bed (dry-pot) and in the actual in-service use as a cutting edge. The laboratory wear tests produced results that are well comparable with the in-service case observations. Especially at the higher sample rotation speed with granite as an abrasive, the wear rates were quite similar as determined from the cutting edge of a loader bucket that had been used in a mine.submittedVersionacceptedVersionPeer reviewe

Impact-abrasion wear of wear-resistant steels at perpendicular and tilted angles

Earth moving and processing machinery has to withstand heavy wear caused by impacts and scratching by the soil. Especially, the edges are subjected to heavy wear. To simulate these conditions, impeller–tumbler impact-abrasion wear testing equipment was used to determine the wear resistance of four steel grades at perpendicular and tilted sample angles. The angles were selected to simulate the loading conditions. Natural granite rock was used as abrasive. The amount of wear was clearly smaller in the harder materials. The significance of hardness was quite similar at both sample angles in the steady-state wear of wear-resistant steels. On the initial state wear, hardness had a slightly greater effect at the perpendicular angle due to more severe wear in sample edges already at the beginning of the test. Overall, the largest differences in wear were observed in the sample edges. At the perpendicular sample angle, the sample edges were much more rounded. Some small differences were observed in the surface formations due to dissimilar movement of the abrasive. Deformed surfaces and fractured lips indicated that wear occurred mainly by the deformation of material followed by the removal of the deformed areas through impacts. In addition, scratches and dents were observed. It was found that larger sized abrasives caused higher mass loss than abrasives of similar mass but smaller size. Moreover, same amount of abrasive particles in each test reduces the scatter of the results. </jats:p