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| 3. |
- Grenmyr, Gustav, et al.
(författare)
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Analysis of Tool Wear in CGI Machining
- 2008
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Ingår i: IMETI 2008. ; , s. 34-39
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Konferensbidrag (refereegranskat)abstract
- In this study the tool wear and wear mechanisms on coated cemented carbide inserts were investigated in turning of Compacted Graphite Iron (CGI) materials with different nodularity. Investigation of how small changes in nodularity affect the wear behaviour of inserts in CGI machining has not earlier been done. The inserts were examined in LOM, SEM and in EDX. The tool wear could on the basis of their wear appearance be classified in three different wear categories; A, B and C. In the wear category A, abrasive wear, adhesive wear and delamination wear could be seen. In the wear category B, the predominant wear mechanism was chipping. The wear appearance in wear category C indicated attrition wear and dissolution via diffusion. Classification of the wear mechanisms gave knowledge that could be used in tool design. The results showed that increasing nodularity has impact on wear at moderate and high cutting speed but not at lower cutting speed. Machining of all materials at high cutting speed, 400 m/min, led to complete degradation of the edge line. A small difference in nodularity from 5% to 20% has more significant impact on wear than from 20% to 62%. This seemed to be correlated with the difference in ultimate tensile strength between the materials.
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| 4. |
- Grenmyr, Gustav, 1982, et al.
(författare)
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Analysis of Tool Wear in CGI Machining
- 2008
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Ingår i: Proceedings of International Multi-Conference on Engineering and Technological Innovation, June 29th - July 2nd, 2008 – Orlando, Florida, USA. ; Volume I, s. 34-39
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Konferensbidrag (refereegranskat)
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| 5. |
- Grenmyr, Gustav, 1982, et al.
(författare)
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Investigation of tool wear mechanisms in CGI machining
- 2011
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Ingår i: International Journal of Mechatronics and Manufacturing Systems. - : Inderscience publisher. - 1753-1039 .- 1753-1047. ; 4:1, s. 3-18
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the tool wear, including wear mechanisms on coated cemented carbide inserts were investigated in the turning of Compacted Graphite Iron (CGI) materials with varying nodularity. The results showed that increasing nodularity, in the range of 5–62%, affects wear at moderate and high cutting speeds without having the same impact at lower cutting speeds. A small difference in nodularity, in the lower range, such as an increase from 5% to 20%, has a more significant impact on wear than an increase from 20% to 62%.
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| 6. |
- Hosseini, Seyed, 1981, et al.
(författare)
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A Methodology for Temperature Correction When Using Two-Color Pyrometers : Compensation for Surface Topography and Material
- 2014
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Ingår i: Experimental mechanics. - : Springer Science and Business Media LLC. - 0014-4851 .- 1741-2765. ; 54:3, s. 369-377
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Tidskriftsartikel (refereegranskat)abstract
- In this investigation, the applicability of the two-color pyrometer technique for temperature measurements in dry hard turning of AISI 52100 steel was studied, where both machined surfaces as well as cutting tools were considered. The impacts of differing hard turned surface topography on the two-color pyrometer readings was studied by conducting temperature measurements on reference samples created using cutting tools with different degrees of tool flank wear. In order to conduct measurements in a controlled environment, a specially designed furnace was developed in which the samples were heated step-wise up to 1,000 °C in a protective atmosphere. At each testing temperature, the temperatures measured by the two-color pyrometer were compared with temperatures recorded by thermocouples. For all materials and surfaces as studied here, the two-color pyrometer generally recorded significantly lower temperatures than the thermocouples; for the hard turned surfaces, depending on the surface topography, the temperatures were as much as 20 % lower and for the CBN cutting tools, 13 % lower. To be able to use the two-color pyrometer technique for temperature measurements in hard turning of AISI 52100 steel, a linear approximation function was determined resulting in three unique equations, one for each of the studied materials and surfaces. By using the developed approximation function, the measured cutting temperatures can be adjusted to compensate for differing materials or surface topographies for comparable machining conditions. Even though the proposed equations are unique for the hard turning conditions as studied here, the proposed methodology can be applied to determine the temperature compensation required for other surface topographies, as well as other materials. © 2013 Society for Experimental Mechanics.
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| 7. |
- Hosseini, Seyed, 1981, et al.
(författare)
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Characterization of the Surface Integrity induced by Hard Turning of Bainitic and Martensitic AISI 52100 Steel
- 2012
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Ingår i: Procedia CIRP. - : Elsevier BV. - 2212-8271. ; 1:1, s. 494 - 499
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Konferensbidrag (refereegranskat)abstract
- Depending on the process parameters and the tool condition, hard turned surfaces can consist of a “white” and a “dark” etching layer having other mechanical properties compared to the bulk material. X-ray diffraction measurements revealed that tensileresidual stresses accompanied with higher volume fraction of retained austenite are present in the thermally induced white layer. While compressive residual stresses and decreased retained austenite content was found in the plastically created white layer. The surface temperature was estimated to be ~1200 C during white layer formation by hard turning.
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| 8. |
- Hosseini, Seyed, 1981, et al.
(författare)
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Cutting temperatures during hard turning : Measurements and effects on white layer formation in AISI 52100
- 2014
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 214:6, s. 1293-1300
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the temperature evolution during white layer formation induced by hard turning of martensitic and bainitic hardened AISI 52100 steel, as well as the effects of cutting temperatures and surface cooling rates on the microstructure and properties of the induced white layers. The cutting temperatures were measured using a high speed two-colour pyrometer, equipped with an optical fibre allowing for temperature measurements at the cutting edge. Depending on the machining conditions, white layers were shown to have formed both above and well below the parent austenitic transformation temperature, Ac1, of about 750 C. Thus at least two different mechanisms, phase transformation above the Ac1 (thermally) and severe plastic deformation below the Ac1 (mechanically), have been active during white layer formation. In the case of the predominantly thermally induced white layers, the cutting temperatures were above 900 C, while for the predominantly mechanically induced white layers the cutting temperatures were approximately 550 C. The surface cooling rates during hard turning were shown to be as high as 104-105 C/s for cutting speeds between 30 and 260 m/min independent of whether the studied microstructure was martensitic or bainitic. Adding the results from the cutting temperature measurements to previous results on the retained austenite contents and residual stresses of the white layers, it can be summarised that thermally induced white layers contain significantly higher amounts of retained austenite compared to the unaffected material and display high tensile residual stresses. On the contrary, in the case of white layers formed mainly due to severe plastic deformation, no retained austenite could be measured and the surface and subsurface residual stresses were compressive. © 2014 Elsevier B.V.
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| 9. |
- Hosseini, Seyed, 1981, et al.
(författare)
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Microstructure characterization of white layer formed by hard turning and wire electric discharge machining in high carbon steel (AISI 52100)
- 2012
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Ingår i: Advanced Materials Research. - 1662-8985 .- 1022-6680. ; 409, s. 684-689
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Konferensbidrag (refereegranskat)abstract
- White layers, formed during hard turning and wire electric discharge machining, werecharacterized by means of X-ray diffraction, scanning electron microscopy and transmissionelectron microscopy. Different cutting speeds and flank wear were utilized in order to obtaindifferent thermally and/or plastically deformed white layer. Since the white layer after wire electricdischarge machining is mainly thermally induced, it was used as a reference structure. In theinvestigation, both bainitic and martensitic structures were studied. With a constant flank wear of0.175 mm the thickness of the white layer increased from 1.5 μm to 3 μm as the cutting speed wasincreased. In both processes the white layer were characterized by nano-sized grains and surfacetensile residual stresses. M3C carbides were observed in the hard turned white layer, indicating thatthe time and temperature needed for completely dissolving the carbides were not reached duringcutting. For both materials the white layers formed by wire electric discharge machining consistedof ~ 30 vol. % of retained austenite. Observation regarding the volume fraction of the retainedaustenite in the white layer formed by hard turning for martensitic material showed an increase inthe volume fraction of retained austenite from ~ 2 - 3 vol. % to ~ 6 vol. %, while this observationwas not seen in the white layer formed in the bainitic material.
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