Interaction time and beam diameter effects on the conduction mode limit

Assunção, Eurico; Williams, Stewart; Yapp, D.

doi:10.1016/j.optlaseng.2012.02.001

Cited by 101 publications

(31 citation statements)

References 18 publications

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“…As we can see in Assuncao study [16] The use of a gap tends to make only sharp V shaped welds in the case of partial penetration welds. The assumption can be made that the gap allows an easier penetration for the weld because the melted metal can flow into the gap.…”

Section: Weld Shapementioning

confidence: 82%

Experimental Investigation of Laser Welding Process in Butt-Joint Configurations

Jacques¹,

Ouafi²

2017

WJET

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This paper presents an experimental investigation of laser welding low carbon galvanized steel in butt-joint configurations. The experimental work is focused on the effects of various laser welding parameters on the welds quality. The investigations are based on a structured experimental design using the Taguchi method. Welding experiments are conducted using a 3 kW Nd:YAG laser source. The selected laser welding parameters (laser power, welding speed, laser fiber diameter, gap between sheets and sheet thickness) are combined and used to evaluate the variation of four weld quality attributes (bead width, penetration depth, underfill and hardness) and to identify the possible relationship between welding parameters and weld physical and geometrical attributes. The effects of these parameters are studied using ANOVA to find their contributions to the variation of different weld characteristics. Plots of the main effects and the interaction effects are also used to understand the influence of the welding parameters. The results reveal that all welding parameters are relevant to bead width (BDW) and depth of penetration (DOP) with a relative predominance of laser power and welding speed. The effect of laser fiber diameter on penetration depth is insignificant. Typical gap-dependent weld shapes show that a small gap results in a narrower and deeper weld. Due to the standard sheared edge, an underfill between 5% and 10% occurs for no-gap experiments. The resulting hardness values are relatively similar for all the experimental tests.

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Section: Weld Shapementioning

confidence: 82%

Experimental Investigation of Laser Welding Process in Butt-Joint Configurations

Jacques¹,

Ouafi²

2017

WJET

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“…In this mode, an upward temperature gradient is formed distributing the material flow in the fusion zone in a Marangoni convection process, which is responsible for the geometry of the laser melt pool, shape, aspect ratio, and composition [15]. Due to this convection, there is a NiTi-rich liquid drift towards the left side of the melt pool (as suggested by the arrows in Fig.…”

Section: Resultsmentioning

confidence: 99%

Fiber laser welding of NiTi to Ti-6Al-4V

Miranda

Assunção

Silva

et al. 2015

Int J Adv Manuf Technol

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Joining of multimaterials is a major issue for several industrial applications where the combination of individual material properties increases component performance. The objective of this experimental study is to assess the laser weldability of NiTi to Ti-6Al-4V. Dissimilar welds were performed on 1-mm-thick plates with a high-power fiber laser with different heat inputs to control the cooling rate. Fracture was always observed in the weld metal in a solidification cracking phenomena. Scanning electron microscopy with EDS was performed to analyze the fracture surfaces. Solidification cracking was observed in the fusion zone associated to Ti 2 Ni formation in two distinct fracture morphologies: brittle transgranular cracking in the Ti 2 Ni regions and dimple intergranular failure along the solidification dendrites. Thus, autogeneous welding of these two materials is difficult due to intermetallics formation and filler materials or interlayers are needed to prevent the formation of brittle intermetallics.

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“…In conduction mode, the power density applied is insufficient to cause significant vaporisation; heat is absorbed from the laser beam through the top surface of the metal. In keyhole mode, however, the power density is high enough not only to vaporise material, but also to open a hole in the melt pool [7]. The conduction mode is also characterised by a semi-cylindrical shape, while the keyhole or penetration mode is characterised by a deep narrow shape [8].…”

Section: Laser Melting Of the Substratementioning

confidence: 99%

Evaluation of Single Tracks of 17-4ph Steel Manufactured at Different Power Densities and Scanning Speeds by Selective Laser Melting

Makoana

Möller

Burger

et al. 2016

SAJIE

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In Selective Laser Melting, the initial units produced are single tracks that overlap to create a single layer; from the sequence of layers, a 3D object is manufactured. The properties of the parts produced by SLM depend heavily on the properties of each single track and each layer formed by these tracks. This study evaluates the effect of processing parameters on the geometrical characteristics of single tracks manufactured from 17-4PH stainless steel powder. A single-mode continuous-wave ytterbium fibre laser was used to manufacture single tracks at laser powers in the range of 100-300 W with a constant spot size of ∼80µm. The single tracks produced were subjected to standard metallographic preparation techniques for further analysis with an optical microscope. Deep molten pool shapes were observed at low scan speeds, while shallow molten pool shapes were observed at high scan speeds. At higher laser power densities, under-cutting and humping effects were also observed. The dimensions of single tracks processed without powder generally decrease with increasing scan speed at constant laser power. However, the geometrical features of the single tracks processed with powder revealed pronounced irregularities believed to be caused by non-homogeneity in the deposited powder layer. OPSOMMINGSelektiewe lasersmelting produseer enkel bane wat mekaar oordek en vorm so ŉ enkele laag. Daaropvolgende lae vorm dan ŉ driedimensionele onderdeel. Die eienskappe van hierdie onderdele word grootliks beïnvloed deur die eienskappe van elke baan en elke laag. Hierdie studie evalueer die effek van die prosesseringsparameters op die geometriese eienskappe van enkel bane wat van 17-4PH vlekvrye staalpoeier vervaardig is. ŉ Enkelmodus kontinuegolf ytterbium vesel laser is gebruik om die enkel bane te vervaardig. Die laser drywing het gewissel van 100 tot 300W met ŉ konstante kolgrootte van ongeveer 80µm. Die enkel bane is dan aan standaard metallografiese voorbereidingstegnieke onderwerp sodat verdere analise met ŉ optiese mikroskoop kon geskied. Diepgesmelte poel vorms is bespeur teen lae skandeersnelhede, terwyl vlakgesmelte poel vorms by hoë skandeersnelhede gewaar is. By hoër laser drywingsdigthede is ondersnyding en hobbelvorming waargeneem. Die dimensies van die enkel bane wat sonder poeier geprosesseer is, het oor die algemeen afgeneem met ŉ toename in skandeersnelheid by konstante laserdrywing. Die geometriese eienskappe van die enkel bane wat wel met poeier geprosesseer is, het noemenswaardige onreëlmatighede aan die lig gebring. Daar word vermoed dat die onreëlmatighede as gevolg van nie-homogene verskynsels in die gedeponeerde poeierlaag is.

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Interaction time and beam diameter effects on the conduction mode limit

Cited by 101 publications

References 18 publications

Experimental Investigation of Laser Welding Process in Butt-Joint Configurations

Experimental Investigation of Laser Welding Process in Butt-Joint Configurations

Fiber laser welding of NiTi to Ti-6Al-4V

Evaluation of Single Tracks of 17-4ph Steel Manufactured at Different Power Densities and Scanning Speeds by Selective Laser Melting

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