An experimental investigation into the defects of laser-drilled holes in thermal barrier coated Inconel 718 superalloys

Delamination and microcracks as well as spatters are known to be inherently associated with laser drilling thermal barrier coated materials. In this study, response surface method (RSM) and single-variable method were employed to correlate the laser parameters including pulse length, peak power, pul...

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Bibliographic Details
Published in:International journal of advanced manufacturing technology 2018-04, Vol.96 (1-4), p.1467-1481
Main Authors: Wang, Rujia, Wang, Kedian, Dong, Xia, Fan, Zhengjie, Duan, Wenqiang, Mei, Xuesong, Wang, Wenjun, Cui, Jianlei, Zhang, Shuai
Format: Article
Language:English
Subjects:
CAE) and Design
Coating effects
Computer-Aided Engineering (CAD
Defects
Delamination
Drilling
Electrons
Engineering
Fracture mechanics
Industrial and Production Engineering
Laser drilling
Lasers
Mechanical Engineering
Media Management
Microcracks
Nickel base alloys
Nitrogen dioxide
Original Article
Percussion
Percussion drilling
Pulse rate
Response surface methodology
Superalloys
Temperature effects
Thermal barrier coatings
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Summary:Delamination and microcracks as well as spatters are known to be inherently associated with laser drilling thermal barrier coated materials. In this study, response surface method (RSM) and single-variable method were employed to correlate the laser parameters including pulse length, peak power, pulse rate, and pulse numbers as well as the interactions among them with such defects in laser percussion drilling. Detailed observation and analysis reveals that narrow pulse length, lower peak power, and low pulse rate can produce smaller cracks area on the side wall, among which the effect of pulse length is more outstanding. As for spatters around hole entrance, the interactions among these factors were identified and a combination of higher peak power, proper pulse length (in this model not exceed 1 ms), higher pulse rate, and small number of pulses are conducive to minimize the spatter volume. Furthermore, the thermal effect near the thermal barrier coating/bond coat (TBC/BC) is especially prominent in laser drilling with wide pulse length and low peak power. The removal mechanism occurred near TBC/BC also determines the delamination crack size. And higher peak power with narrow pulse length should be a good strategy in order to break through the TBC as soon as possible and shelter the TBC or TBC/BC from thermal damage.
ISSN:0268-3768
1433-3015
DOI:10.1007/s00170-018-1592-y