Geometrical features and metallurgical characteristics of Nd:YAG laser drilled holes in thick IN718 and Ti–6Al–4V sheets

Bandyopadhyay, Sambaran; Sundar, Jeyaperumal Kalyana; Sundararajan, G.; Joshi, Shrikant V.

doi:10.1016/s0924-0136(02)00270-4

Cited by 167 publications

(84 citation statements)

References 22 publications

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“…This provides direct proof that no melting occurred and suggests that material removal was completely accomplished by a vaporization process. In the previous studies [12,25], recast layers and heat-affected zones within at least 10 m thickness were observed adjacent to the processed zones in copper, Ni-base superalloys and titanium alloys with nanosecond lasers. The direct ablation that occurs with the use of femtosecond lasers is clearly desirable from the point of view of minimizing damage.…”

Section: Discussionmentioning

confidence: 86%

“…However, a number of defects are inherently associated with current laser drilling systems. As mentioned previously, these include spatter, recast layer, microcracks and taper of the drilled hole, as well as delamination at the interfaces of dissimilar material layers [4,5,10,11,12,13,14]. These defects affect the metallurgical and geometrical quality and presumably limit the performance of materials.…”

Section: Discussionmentioning

confidence: 99%

“…Conventional nanosecond (10 -9 s) and picosecond (10 -12 s) laser systems produce distinct heat-affected zones and recast layers, since there is enough time for a thermal pulse to propagate into the material [7,8,9]. Therefore, a number of processing defects are encounted including spatter, remelted layers, microcracking, tapering of the drilled hole as well as the delamination of interfaces in the case of TBCs [4,5,10,11,12]. Laser-induced cracking in TBC-coated superalloys has been observed at both the bond coat/substrate and bond coat/TBC (top coat) interfaces [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Laser-induced cracking in TBC-coated superalloys has been observed at both the bond coat/substrate and bond coat/TBC (top coat) interfaces [13,14]. Previous parametric studies revealed that the quality of drilled holes depends on material properties and the optimization of laser processing parameters, such as laser fluence, pulse duration, pulse repetition rate and pulse shape [4,12,15]. However, the above-mentioned processing defects are inherent to these laser machining processes.…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond Laser Micromachining of Single-Crystal Superalloys

Feng

Picard

Liu

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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Investigations on femtosecond laser micromachining of single crystal superalloys with and without plasma-sprayed thermal barrier coatings were conducted under laser fluences ranging from 0.1 J/cm 2 up to 160 J/cm 2 . Micromachining was carried out in air using a titanium:sapphire laser system ( = 780 nm) operating at a repetition rate of 1 kHz and delivering individual pulses of ~150 fs duration. The ablation threshold of the single crystal superalloy was determined as 203 ± 20 mJ/cm 2 . Laser-induced damage was examined by means of scanning electron microscopy and transmission electron microscopy. These studies indicate a complete absence of any melting, recast layers, heat-affected zones or microcracks in the vicinity of the machining area. The only form of damage observed in the single crystal superalloy machined near or above the ablation threshold was a laser-induced plastically deformed layer with a maximum extent of ~5 m. Machining through ceramic thermal barrier coatings on a superalloy produced no delamination along the superalloy/coating interfaces or cracks within the TBC or bond coat. The residual roughness of the machined surface was in the sub-micron range. The present study suggests that femtosecond laser micromachining is a very promising technique for production of finescale features in multi-layer material systems for aerospace and power generation components.

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Femtosecond Laser Micromachining of Single-Crystal Superalloys

Feng

Picard

Liu

et al. 2004

Superalloys 2004 (Tenth International Symposium)

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“…The effect of pulsed Nd:YAG laser percussion drilling process parameters on the geometrical [18][19][20] and metallurgical [21][22][23] quality characteristics has been established in previous studies.…”

Section: Introductionmentioning

confidence: 99%

Investigation of recast and crack formation in laser trepanning drilling of CMSX-4 angled holes

Morar

Roy

Mehnen

et al. 2018

Int J Adv Manuf Technol

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This paper presents an experimental investigation on the influences of laser trepanning drilling process parameters on the recast layer thickness and surface crack formation in CMSX-4 nickel-based superalloy angled holes. The effects of peak power, pulse frequency and the trepanning speed as input parameters were investigated in details by varying the laser drilling conditions using Taguchi orthogonal array-based design of experiment approach. Analysis of variance identifies the significant parameters affecting the output responses. It is found that the output responses are affected mainly by the peak power and trepanning speed. The experimental results reveal that the recast layer thickness increases with the increase of peak power and trepanning speed whereas the crack number density decreases with the increase of peak power only. Pulse frequency has no significant effect on both output responses within the range of values investigated. The knowledge gained in this parametric study could be used to improve the metallurgical characteristics of laser-drilled nickel-based acute angled holes.

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Lasers in Aerospace Industry Manufacturing

Mazumder

2010

Encyclopedia of Aerospace Engineering

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The Aerospace Industry has adopted laser technology from its early days and several laser‐aided manufacturing processes have become routine. Lasers can deliver energy from zero to a trillion watts in a small spot in an instant. That generated a wide portfolio. For example, laser peening needs more than 10 9 W cm −2 , whereas laser welding can be accomplished with 10 6 W cm −2 ; laser drilling requires 10 8 W cm −2 compared to 10 5 W cm −2 or more for laser cladding and solid free form formation. The mechanism for different processes is different although the energy source is common. Interaction time for each process is different, too. Laser shock peening utilizes nanosecond pulses compared to millisecond pulses for drilling. Welding and cladding are generally carried out with continuous wave. The role they play is also varied. Drilling generates cooling holes for turbine blades to enhance the operating temperature whereas shot peening produces residual compressive stress on the blades to improve fatigue properties and reduce crack propagation. Welding is mostly used to join structural components whereas cladding repair of reconfigured aerospace components is used to increase their service life. This chapter will discuss the four most common uses of lasers in Aerospace Industry Manufacturing.

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Geometrical features and metallurgical characteristics of Nd:YAG laser drilled holes in thick IN718 and Ti–6Al–4V sheets

Cited by 167 publications

References 22 publications

Femtosecond Laser Micromachining of Single-Crystal Superalloys

Femtosecond Laser Micromachining of Single-Crystal Superalloys

Investigation of recast and crack formation in laser trepanning drilling of CMSX-4 angled holes

Lasers in Aerospace Industry Manufacturing

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