| 1. |
- Al-Mashikhi, S.O, et al.
(author)
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Heat affected zones and oxidation marks in fiber laser–oxygen cutting of mild steel
- 2011
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In: Journal of laser applications. - : Laser Institute of America. - 1042-346X .- 1938-1387. ; 23:4
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Journal article (peer-reviewed)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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| 2. |
- Hashemzadeh, M., et al.
(author)
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Fibre laser piercing of mild steel : The effects of power intensity, gas type and pressure
- 2014
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In: Optics and lasers in engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 55, s. 143-149
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Journal article (peer-reviewed)abstract
- Laser piercing is used to generate a starting point for laser cutting. The pierced hole is normally larger than the kerf width, which means that it cannot lie on the cut line. An experimental programme investigating the piercing process as a function of laser and assist gas parameters is presented. An Nd:YAG fibre laser with a maximum power of 2 kW was used in continuous wave mode to pierce holes in 2 mm thick mild steel. Oxygen and nitrogen were used as assist gases, with pressures ranging from 0.3 to 12 bar. The sizes, geometries and piercing time of the holes produced have been analysed. The pierced hole size decreases with increasing gas pressure and increasing laser power. Oxygen assist gas produced larger diameter holes than nitrogen. A new technique is presented which produces pierced holes no larger than the kerf with and would allow the pierced hole to lie on the cut line of the finished product – allowing better material usage. This uses an inclined jet of nitrogen when piercing prior to oxygen assisted cutting.
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| 3. |
- Hashemzadeh, M., et al.
(author)
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The Application of Specific Point Energy Analysis to Laser Cutting with 1 μm Laser Radiation
- 2014
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In: Physics Procedia. - : Elsevier BV. - 1875-3892. ; 56, s. 909-918
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Journal article (peer-reviewed)abstract
- Specific point energy (SPE) is a concept that has been successfully used in laser welding where SPE and power density determine penetration depth. This type of analysis allows the welding characteristics of different laser systems to be directly compared. This paper investigates if the SPE concept can usefully be applied to laser cutting. In order to provide data for the analysis laser cutting of various thicknesses of mild steel with a 2 kW fibre laser was carried out over a wide range of parameter combinations. It was found that the SPE concept is applicable to laser cutting within the range of parameters investigated here.
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| 4. |
- Powell, John, et al.
(author)
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Fibre laser cutting of thin section mild steel : An explanation of the ‘striation free’ effect
- 2011
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In: Optics and lasers in engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 49:8, s. 1069-1075
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Journal article (peer-reviewed)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/oxygen 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 lasermaterial combination
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