The Joining of DED parts by Laser Welding

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Back to Core Research Programme AMorph – 4D Printing for Field Morphing Structures Automation of Composite and Hybrid Joining Process Coaxial Wire Additive Manufacturing Processes and In-Line Monitoring Tools Development of Coded Excitation Technique for Non-Metallic Pipes Inspection Development of Digital Twin technology as a demonstrator for real-time integrity assessment of crack growth in tensile specimens Development of Friction Stir Welding (FSW) for Hydrogen Fuel Storage Tanks Development of Leak-Before-Break Hydrogen Storage Composite Pressure Vessels With Polymeric Liner Establishing Assessment Methods for Determining Safe Service Limits of High-Temperature Materials in Extreme Environments Fracture toughness in aggressive environments: effect of crack monitoring techniques on test results In-process detection and non-destructive testing of electron beam weld imperfections Internal Bore Coatings for Applications in Corrosion and Hydrogen Environment Joining of Additively Manufactured Materials Long term behaviour of polymeric liner materials/coatings in hydrogen service Techniques for High Temperature Ultrasonic Inspection of Arc Welding Ultimate Leverage Fund

Project Code: 35929

Start date and planned duration: April 2024, 36 months

Objective

Evaluate suitability of laser welding parts produced by DED (coaxial laser/wire) to create larger/more complex assemblies.
Explore novel coaxial wire DED processing to meet near net shape targets, deposition rates and material properties and to evaluate reliance on in-process sensing technology.
Explore the design requirements of DED built geometric features that could offer advantages to help facilitate laser welding (i.e. welding parts with thicker cross sections >8-10mm).
Evaluation of the need of sensors during laser welding to help improve process robustness.

Project Outline

The project will focus on laser DED with wire feeding (w-DED-LB) and laser welding. Candidate materials, aligned to industrial mentor requirements include steels and stainless steels and Ni and Ti alloys. In particular, a novel coaxially fed wire deposition head will be explored for more agile deposition. Furthermore, oscillating or scanning beam optics will be used to join build geometries in aid of achieving good quality welds. There are several reasons for opting for these technologies over other DED and welding processes (the knowledge gained from this project would however, be applicable across all DED processes):

Wire, and not powder feedstock, is better suited for the manufacture of large structures.
Laser DED has the greatest precision (compared to WAAM) and imparts much less heat input (compared to WAAM and EB) to minimise distortion during manufacture. This all helps to minimise the amount of post build machining.
The coaxial wire DED process head currently installed at TWI has been reported by the manufacturer of not requiring in process sensing and offers a robust manufacturing DED option. This claimed process robustness will be explored in this project.
From TWI’s experience, porosity within the DED part is likely to then manifest as pores in the welds. Laser beam scanning and oscillating techniques will help to disperse and control porosity formation, as well as delivering tailored energy distributions to positively influence weld quality (i.e. minimising occurrence of porosity, achieving consistency of weld profile and for avoidance of lack of fusion/lack of penetration defects).
In support of establishing a robust approach for welding DED assemblies, weld process sensor data will also be collected during experimental trials using commercially proven in-process monitoring approaches available at TWI (i.e. in-process camera imaging, Optical Coherence Tomography (OCT)). This activity will be supporting robust process development during welding operations.

Successful delivery of proposed concept will also enable the potential of using the same laser machines and setups for covering both the DED and joining operations. This is expected to bring a strong added value in terms of reduced capital equipment, running costs, reduced floor space in production, enabling a more agile, cost effective and efficient manufacturing solution.

Industry Sectors

- Defence

- Power, Nuclear

- Marine

Benefits to Industry

The platform solution will constitute an important building block in enhancing the benefits of power beam processing to a wide range of manufacturing processes, not limited only to the yellow goods, nuclear and aerospace sector, but also including defence, power and marine sectors.
Within industry there is a strong need for agile, while robust, manufacturing solutions, ensuring robust performance repeatability and process robustness. The proposed approach of using in-process monitoring sensor technologies in support to both the laser joining and DED processes will aim to provide an industrial solution to reduce
This project aims to provide members with more confidence around the robustness of laser welding DED parts (laser/wire) and it is suitability for higher TRL applications and industrial up-take.
Members will gain a greater awareness of state-of-the-art joining and AM processes along with the specific benefits and achievable properties of each
Members will have access to critical data (process economics, microstructural and material properties) to help make informed decisions on what technology solutions are most suited to their applications
Industrial members will be able to take advantage of the capabilities gained by TWI in this CRP project to improve their knowledge of laser joining of DED parts both in terms of quality monitoring and improved manufacturing.
Production line improved by envisioning new manufacturing process with improved defect detection, achievement of key performance requirements, re-work and scrap rate reduction.
Manufacturing times and costs, by minimising scrap and reducing the need for post-welding inspection of joints.