| 1. |
- Al-Mashikhi, S.O., et al.
(författare)
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An explanation of ‘striation free' cutting of mild steel by fibre laser
- 2009
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Ingår i: Lasers in manufacturing 2009. - Stuttgart : AT-Fachverlag.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an experimental and theoretical investigation into the phenomenon of ‘striation free cutting', which is a feature of fibre laser cutting of thin section mild steel. The paper concludes that the creation of very low roughness edges is related to an optimisation of the cut front geometry when the cut front is inclined at angles close to the Brewster angle for the laser - material combination. For purely geometric reasons this particular type of cut front optimisation is not possible for CO2 laser cutting of mild steel.
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| 2. |
- Al-Mashikhi, S.O, et al.
(författare)
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Heat affected zones and oxidation marks in fiber laser–oxygen cutting of mild steel
- 2011
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 23:4
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Tidskriftsartikel (refereegranskat)abstract
- The effect of cutting speed and sheet thickness on surface oxidation and heat affected zones (HAZs) has been investigated for laser–oxygen cutting of mild steel sheet with a fiber laser. Optical and scanning electron micrographs were used to determine the extent of surface oxidation and HAZ from plan and cross-sectional views, respectively. The HAZ is consistently wider at the bottom of the cut compared to the HAZ at the top of the cut. With increasing speed, the width of the HAZ at the top of the cut decreases whereas the HAZ width at the bottom of the cut generally increases. No simple, direct relationship between HAZ width and surface oxidation was seen. However, it is possible to state that in each case considered here, the HAZ would be completely removed if they are machined back by a depth equal to the extent of the surface oxidation.
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| 3. |
- Alam, Md. Minhaj, et al.
(författare)
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Surface pore initiated fatigue failure in laser clad components
- 2013
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Ingår i: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 25:3
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Tidskriftsartikel (refereegranskat)abstract
- A laser clad and machined cylindrical structural steel rod was fatigue tested under four-point bending load. The resulting fracture could be tracked back to a spherical surface pore in the Co-based coating. Due to an oxide inclusion, the pore was not identified by dye penetrant inspection. Two circular buckling strain patterns that were detected beside the pore at the surfaces after fracture confirm local plastic deformation prior to crack initiation. In order to calculate the stress field around the surface pore, linear elastic finite element analysis was carried out. For four-point bending load, a surface pore generally exceeds the maximum stress of a smooth rod as long as the pore is located within an azimuthal angle of ±55°, which was the case for the presented as well as for another pore initiated sample.
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| 4. |
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| 5. |
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| 6. |
- Andersson, Roger, et al.
(författare)
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Formability behaviour of meta-stable stainless steels
- 2005
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Ingår i: Proceedings of the 8th ESAFORM Conference on Material Forming. - Bucharest : The Romanian Academy Publishing House. - 9732711736 ; , s. 359-362
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Konferensbidrag (refereegranskat)
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| 7. |
- Atiyah, H., et al.
(författare)
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Fiber laser cutting : The use of carbon-filled acrylic as a qualitative and quantitative analysis tool
- 2018
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Ingår i: Journal of laser applications. - : American Institute of Physics (AIP). - 1042-346X .- 1938-1387. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- The use of carbon-filled black acrylic (CFBA) as a quantitative and qualitative analytical tool for fiber laser cutting is investigated. In the qualitative work, CFBA targets placed below the laser cutting zone when cutting stainless steel showed a distinctive “leaf” shaped evaporation crater which can provide information about the nature of the reflections taking place in the cut zone. Quantitative measurements have revealed a specific evaporation energy of 3.4 J/mm3 for CFBA. However, this figure is only applicable when considering intense beams when the CFBA target is stationary with respect to the laser beam.
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| 8. |
- Bergström, David, et al.
(författare)
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A ray-tracing analysis of the absorption of light by smooth and rough metal surfaces
- 2007
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 101:11, s. 113504-1
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Tidskriftsartikel (refereegranskat)abstract
- Ray tracing has been employed to investigate the absorption of light by smooth and random rough metal surfaces. For normally incident light the absorptance of the surface increases with surface roughness. However, for light incident at a tangent to the surface the absorptance-surface roughness relationship is more complex. For example, in certain cases the absorptance can rise, fall, and rise again as the surface roughness increases. In this paper this complex absorptance-roughness relationship is defined and explained. The wavelengths of the light chosen for this study correspond to the primary and secondary output wavelengths of Nd:YAG lasers.
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| 9. |
- Bergström, David, et al.
(författare)
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Absorptance of Non-Ferrous Alloys to Nd:YLF and Nd:YAG Laser Light at Room Temperature
- 2007
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 46:8, s. 1290-1301
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Tidskriftsartikel (refereegranskat)abstract
- The measurement of absorptance is important for the analysis and modelling of laser-material interactions. Unfortunately, most of the absorptance data presently available considers only polished pure metals rather than the commercially available (unpolished, oxidised) alloys which are actually being processed in manufacturing. This paper presents the results of absorptance measurements carried out at room temperature on as-received engineering grade non-ferrous metals (Al, Cu and Zn alloys). The measurements were made using an integrating sphere with an Nd:YLF laser at two wavelengths (1053nm and 527nm � which means that the results are also valid for Nd:YAG radiation at 1064nm and 532nm). The absorptance results obtained differ considerably from existing data for polished, pure metals and should help improve the accuracy of laser-material interaction models. Some clear trends were identified. For all 22 cases studied the absorptance was higher than for ideal pure, polished metals. For all Al- and Cu-samples the absorptance was higher for the green than it was for the infrared wavelength, while for all Zn-coatings this trend was reversed. No clear correlation between absorptance and surface roughness was found at low roughness values (Sa 0.15 � 0.60) but one, rougher set of samples (Sa 2.34), indicated a roughness-absorptance correlation at higher roughness levels.
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| 10. |
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