Jon Blackburn

The Welding Institute

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Paul Hilton

Granta Design (United Kingdom)

Chris Allen

Nelson Mandela University

Ali Hossain Khan

S.N. Bose National Centre for Basic Sciences

Paola De Bono

Granta Design (United Kingdom)

L. Quintino

University of Lisbon

Gongqi Shi

Granta Design (United Kingdom)

Eurico Assunção

University of Lisbon

L. Li

Qingdao University of Science and Technology

Charles M. Allen

Worcester Polytechnic Institute

Baohua Chang

Tsinghua University

Cooperative Institutions

Granta Design (United Kingdom)

The Welding Institute

University of Manchester

Huazhong University of Science and Technology

Thermal Wave Imaging (United States)

Chinese Academy of Sciences

Beijing Institute of Aeronautical Materials

University West

Tsinghua University

Ministry of Education of the People's Republic of China

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Meeting weld quality criteria when laser welding Ni-based alloy 718

Ali Hossain Khan Paul Hilton Jon Blackburn Chris Allen

Significant numbers of aero-engine parts are manufactured with Ni-based superalloys because of their excellent heat and corrosion resistance properties. Weld imperfections, such as those associated with bead geometry, sub-surface porosity and liquation cracking are of concern, given the high-performance service requirements of fabricated Ni-based components in the aerospace sector. Weld quality criteria are stipulated in AWS D17.1M:2010, a standard for the fusion welding of aerospace components although it is known that more stringent criteria, usually company-specific to various aero-engine manufacturers, also exist.In this paper, a high beam quality 1 µm laser source was used to determine the effects of different process parameters on the quality of melt runs made in 3.35 and 5mm thickness Alloy 718. The principal focus of the work was to compare the results obtained for weld geometry, sub-surface porosity and liquation cracking to the Class A weld quality requirements of AWS D17.1M:2010 and a generic, more stringent company-specific standard.The results show that AWS D17.1M:2010 geometry and porosity criteria can be achieved over a fairly wide process window of speed and power with the laser and optical configuration used. This window is greatly reduced in order to produce liquation crack free welds. If, in addition, it is also required to meet the more stringent company-specific criteria for porosity and weld geometry, the window is even further reduced.

Liquation

Fusion welding

10.2351/1.5062506

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Citations (7)

Laser processing of thin copper and aluminium thin sheets with green (532nm) and infrared (1064nm) pulsed laser beam sources

Paola De Bono Ioannis Metsios Jon Blackburn Paul Hilton

In this study processing of thin copper C101 (Cu C101) and aluminium 3003 (Al 3003) were investigated, using both infrared (IR), at 1064nm wavelength, and green, at 532nm wavelength, pulsed laser beam sources. The power density (peak power divided by the area of the minimum focused laser beam width) thresholds for keyhole initiation, when processing with the 1064nm laser source, were identified as 59kW/mm2 and 21kW/mm2 for 1mm thickness Cu C101 and Al 3003 coupons respectively. Melt depths up to 400µm were achieved in Cu C101 by tailoring the pulse energy. Melt depths up to 650µm were achieved in the case of Al 3003, with the power density of the laser pulse having a significant effect on the resultant melt depth. Conduction limited melting and welding was carried out in the case of the green wavelength, due to the limited output power of the 532nm pulsed laser sources available. The increased absorptivity of Cu C101 at 532nm introduced improved stability in the process, compared to the results achieved with the 1064nm wavelength laser beam. However, the same behaviour was not observed in the case of Al 3003.

Keyhole

Power density

10.2351/1.5062925

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Citations (7)

Laser welding of copper and aluminium battery interconnections

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2015)

Paola De Bono Jon Blackburn

The adoption of lithium-ion and/or super-capacitor battery technologies is a current hot topic in the automotive industry. For both battery types, the terminals and busbars are manufactured from copper (Cu) and/or aluminium-based (Al-based) alloys, as a result of their high electrical and thermal conductivities. Laser welding is considered an attractive process to industry due to its easy automotability, high processing speed and highly repeatable cost-effective processing. However, laser welding of Cu-Cu and Al-Al joints presents several difficulties due to the high surface reflectivity at infrared (IR) wavelengths. This behaviour becomes even more critical when processing thin sheets and foils.This paper summarises recent work performed to develop laser welding techniques suitable for monometallic joining of Cu-Cu and Al-Al electrical interconnections. Laser welding of multiple overlapped foils (with thickness in the range of 17μm-100μm) were investigated.

Busbar

10.1117/12.2176048

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Citations (21)

Laser size reduction of radioactively contaminated structures

Journal of Laser Applications (2018)

Ali Hossain Khan Jon Blackburn

Due to the environment, nuclear decommissioning is an extremely challenging activity. High ambient radiation levels often preclude entry to the areas involved, and as the industry tries to minimize dose uptake, moderate radiation levels are now requiring remote solutions. In situ size reduction of process plant including vessels, containers, dissolvers, and pipework allows the removal of the nuclear inventory from a building prior to further decontamination and demolition. Ex situ size reduction comprises a dedicated facility to take in the existing nuclear waste inventory for further size reduction activity to achieve high waste management efficiencies. Traditional size reduction or cutting methods such as reciprocating saws or grinders pose a significant challenge for remote deployment platforms, where haptic feedback is lost and, when deployed, take considerable time to perform the task. Although remote engineered solutions for these tools are possible, they are complicated, unreliable, and expensive. Laser cutting is widely used in non-nuclear industrial sectors, and offers a more flexible and simpler method for size reduction. This paper presents results of two projects involving in situ and ex situ deployments of high power fiber-delivered lasers on two separate nuclear sites for size reduction of radioactively contaminated structures.

Nuclear decommissioning

Human decontamination

Hot cell

10.2351/1.5040650

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Citations (3)

Progress in additive manufacturing on new materials: A review

Journal of Material Science and Technology (2018)

Neng Li Shuai Huang Guodong Zhang Renyao Qin Wei Liu

Cladding (metalworking)

Material efficiency

10.1016/j.jmst.2018.09.002

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Citations (645)

Microstructure, formation mechanism and property characterization of Ti + SiC laser cladded coatings on Ti6Al4V alloy

Materials Characterization (2018)

Neng Li Xiong Yi Huaping Xiong Gongqi Shi Jon Blackburn

Titanium alloy

Vickers hardness test

10.1016/j.matchar.2018.11.032

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Citations (98)

Modulated Nd : YAG laser welding of Ti–6Al–4V

Science and Technology of Welding & Joining (2010)

Jon Blackburn Charles M. Allen Paul Hilton L. Li M. I. Hoque

Modulating the output of Nd : YAG laser sources has been evaluated as a technique for producing high quality welds in titanium alloys. Welds with high internal quality were produced when a square wave form was used with a modulation frequency ≥125 Hz and a duty cycle of 50%. Undercut present in the weld profile can be reduced if the correct combination of modulation amplitude and laser beam focal plane position are used. High speed observation and subsequent Fourier analysis of the vapour plume and keyhole behaviour have shown that they both exhibit the same periodic tendencies. With the correct parameters, an oscillating wave can be set up in the weld pool, which appears to manipulate the vapour plume behaviour and hence reduce porosity formation.

Keyhole

Undercut

Nd:YAG laser

Duty cycle

Weld pool

10.1179/136217110x12731414739718

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Citations (45)

Numerical sensitivity analysis of single pulse laser welding with a C-shaped beam

Journal of Laser Applications (2015)

Jesper Sundqvist Alexander Kaplan Choon Yen Kong Eurico Assunção L. Quintino

Even though Gaussian and top-hat beam profiles are suitable for most laser welding applications, for certain cases other beam distributions can be favored in terms of weld quality or performance. One promising method to generate a tailored beam shape is diffractive optical elements. A numerical model on the temperature field generated by specific beam shapes is therefore under development to iteratively identify desired beam shapes for specific applications. The present study is based on two thin steel sheets that are conduction welded in a lap joint mode by a C-shaped single laser pulse. The main aim is to ensure a specified weld width along the C-weld shape at the overlap interface between the two sheets in a robust manner. The sensitivity of main criteria like the interface weld width and phase changes at the workpiece top and bottom is studied and discussed in a systematic manner by applying a numerical heat transfer model for various parameters and conditions.

Weld pool

Gaussian beam

Beam parameter product

10.2351/1.4906466

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Citations (5)

Dual Focus Nd:YAG Laser Welding of Titanium Alloys

Springer eBooks (2010)

Jon Blackburn Charles M. Allen Paul Hilton L. Li

Keyhole

Titanium alloy

Weld pool

10.1007/978-1-84996-432-6_64

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Citations (10)

A comparative study of 3D laser surface modification and the humping phenomenon

Caroline Earl Paul Hilton Jon Blackburn Bill O’Neill

Surfi-Sculpt® is a three dimensional surface modification technique that enables functional features to be formed from a substrate material by repeated swipes of a highly focused power beam. Successive swipes of the beam can move molten material so that a protrusion builds up on the surface of the substrate. Characteristics thought similar to the weld instability phenomenon known as humping, have been observed in the Surfi-Sculpt process and it has been proposed that the processes may be related. However, in the Surfi-Sculpt process, the heat input is distributed over a longer duration and at critical time intervals when compared to conventional high speed welding. This work identifies how the Surfi-Sculpt technique can be compared with previously published work on humping parameters and theories. Surfi-Sculpt experiments were carried out with beam swipe speeds between 200 and 1000 mms−1 (within the range of published weld humping speeds of 20 to 1500 mms−1). A single mode fibre laser operating between 200 and 260W was used in this work and the beam was manipulated by an optical scanning system. High speed imaging with dual 500W laser illumination was used to compare experimental results of the two processes with the objective of gaining a greater understanding of the parameter to feature shape relationships and the theory involved in the material movement.

10.2351/1.5062275

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Citations (2)