| 1. |
- Heinrichs, Jannica, et al.
(author)
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Exploring the tribochemical wear and material transfer caused by Cu15Zn alloys on shearing tools
- 2024
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In: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 542
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Journal article (peer-reviewed)abstract
- Cemented carbide tools are extensively used in the zipper industry, including shearing of a pre-formed Cu15Zn wire into individual zipper elements. Although the work material is significantly softer than the tool, wear is the life limiting factor for the tools and is considered to be of tribochemical nature. So far it has not been explained, however, it is known that the wear rate of uncoated, as well as CrC and CrN coated, cemented carbide increases dramatically when Zn is omitted from the Cu alloy. In this paper, worn tool surfaces, including any transferred material, were studied to investigate the tribochemical wear mechanism in detail. Material transfer occurred onto all tool surfaces. Cu and Zn were separated on the sub-micron scale, and preferential transfer of one of the constituents was observed. This is reflected in the outermost surface of the sheared element, which shows a homogeneous composition elsewhere. Oxidation was observed of all tool surfaces, which indicates elements of oxidative wear. Further, any Zn transferred to the tool surfaces was oxidized. Thus, it is suggested that the presence of Zn reduces the oxygen available and consequently reduces the oxidation rate of the tool surfaces, leading to the protective effect previously observed. © 2024 The Authors
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| 2. |
- Heinrichs, Jannica, et al.
(author)
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Influence from surface roughness on steel transfer to PVD tool coatings in continuous and intermittent sliding contacts
- 2012
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In: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 56, s. 9-18
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Journal article (peer-reviewed)abstract
- A sliding test is used in order to evaluate the influence of tool surface roughness on the material transfer in intermittent and continuous sliding of PVD coated HSS against case hardening steel (20NiCrMo2). Two cutting tool coatings, TiN and AlCrN, and three different surface roughnesses are tested. For polished surfaces the same types of material transfer are obtained irrespective of sliding mode and coating type. If the surfaces are too rough, the tribofilms do not grow thick enough to separate the surfaces and the work material is abrasively worn in both sliding modes. With increased sliding distance, cracking of the TiN coating occurs while the AlCrN coating remains intact.
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| 3. |
- Heinrichs, Jannica, et al.
(author)
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Influence of binder metal on wear initiation of cemented carbides in sliding contact with granite
- 2021
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In: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 470-471
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Journal article (peer-reviewed)abstract
- Drill bits equipped with WC-Co cemented carbide buttons offer great performance in many rock drilling applications. Generally, the wear of these buttons against the rock is gradual and moderate, or even slow depending on the rock conditions. However, the Co binder has recently been found to cause health issues and an alternative binder, which does not compromise the performance of the cemented carbide, is needed. In the present work, the performance of WC-Fe and WC-Ni is investigated and compared to the common WC-Co in a sliding test against granite.The results show immediate scrape-off of granite against protruding WC grain edges. Some WC grains crack and fragments are subsequently removed, adding up to loss of entire WC grains. A nanoscale pattern gradually evolves on other WC grains, implying also nanoscale wear. Both WC-Fe and WC-Ni show significantly faster wear initiation and early propagation compared to WC-Co, although the wear characteristics are similar.
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| 4. |
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| 5. |
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| 6. |
- Heinrichs, Jannica, et al.
(author)
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Influence of sliding speed on modes of material transfer as steel slides against PVD tool coatings
- 2013
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In: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 58, s. 55-64
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Journal article (peer-reviewed)abstract
- An intermittent sliding test was used in order to study the formation and build- up of tribofilms during intermittent sliding of PVD coated HSS against case hardening steel (20NiCrMo2). Two cutting tool coatings were tested, TiN and AlCrN, and the influence of sliding speed was evaluated. With moderate speed, two tribofilms were formed separately, one consisting of Mn, Si, Al and O on an intermediate layer of Fe and one consisting of Fe, Mn, Cr and O on an intermediate layer of Cr and Mn. At low sliding speeds an uneven transfer of steel occured while high sliding speeds resulted in thermal softening of the substrate leading to coating failure. AlCrN provided better substrate protection at high speeds than TiN did.
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| 7. |
- Heinrichs, Jannica, et al.
(author)
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Influence of tool steel microstructure on initial material transfer in metal forming-In situ studies in the SEM
- 2013
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In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 302:1-2 SI, s. 1249-1256
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Journal article (peer-reviewed)abstract
- Metal forming constitutes a group of industrially important processes to form metallic components to net shape. When forming aluminium and other materials that tend to stick to the tools, problems associated with material transfer, e.g. galling, may occur. In a previous study by the present authors, in situ observations of aluminium transfer during sliding contact in the SEM revealed that the surface topography and chemical composition of the tool steel counter surface have a strong impact on the initial material transfer tendency. Even if carefully polished to a very smooth surface (Ra < 50 nm), transfer of aluminium was found to immediately take place on a very fine scale and preferentially to the surface irregularities presented by the slightly protruding M(C,N) particles (height 15 nm) in the tool steel. In contrast, the less protruding M6C carbides, as well as the martensitic steel matrix exhibited very little initial transfer. The mechanism behind the preferential pick-up tendency displayed by the M(C,N) particles was not fully understood and it was not possible to determine if the decisive mechanism operates on the microstructural scale, the nanoroughness scale or the chemical bonding scale. In the present study, these mechanisms have been further investigated and analysed by comparing the very initial stages of material transfer onto different types of tool steels in sliding contact with aluminium in the SEM. The tool steels investigated cover conventional ingot cast and powder metallurgy steel grades, selected to possess a range of different types, amounts and sizes of hard phase particles, including MC, M(C,N), M7C3 and M6C. The transfer mechanisms are investigated using high resolution SEM, and the differences between the different microstructures and carbide types are carefully analysed. The implications for real metal forming are discussed.
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| 8. |
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| 9. |
- Heinrichs, Jannica, 1982-, et al.
(author)
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Initial deformation and wear of cemented carbides in rock drilling as examined by a sliding wear test
- 2017
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In: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 64, s. 7-13
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Journal article (peer-reviewed)abstract
- Due to a combination of high hardness and toughness, resulting in excellent wear resistance, cemented carbides are commonly used as the rock crushing component in rock drilling. The present paper presents a unique study where the very initial stages of deformation and wear of cemented carbide in sliding contact with rock are followed in small incremental steps. After each step, a pre-determined area within the wear mark is characterized using high resolution SEM and EDS. This facilitates analysis of the gradual deformation, material transfer, degradation and wear. The deterioration mechanisms found in this sliding test are similar to those observed in actual rock drilling. Cemented carbide grades with different microstructures show significant differences, where a higher amount of Co and a larger WC grain size both are associated to more wear.
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| 10. |
- Heinrichs, Jannica, 1982-, et al.
(author)
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Initial surface failure and wear of cemented carbides in sliding contact with different rock types
- 2018
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In: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 408-409, s. 43-55
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Journal article (peer-reviewed)abstract
- The initial wear, deformation and degradation of cemented carbide in contact with different rock types are studied using a crossed cylinder sliding test. The sliding distance is limited to centimetres at a time, interrupted by successive SEM analysis. This allows for careful studies of the gradually changing microstructure of the cemented carbide during the test. Five different rock types are included; granite, metal sulphide ore, mica schist, quartzite and marble. All rock types are very different in microstructure, composition and properties. The cemented carbide grade used for the evaluation contains 6 wt% Co and fine (~ 1 µm) WC grains, a grade commonly used in rock drilling. The results show that the cemented carbide microstructure becomes altered already during the very first contact with rock. The initial wear rate and wear character is highly influenced by the rock type. The initial wear of the cemented carbide is highest against quartzite and lowest against marble.
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