R. Freeman, M. Dore, L. Zhang, TWI Ltd, Cambridge, United Kingdom; C. Kong, TWI Technology Centre (Yorkshire), Rotherham, United Kingdom
Direct metal laser deposition (DMLD) offers an increasingly attractive additive manufacturing/repair route that can offer advantages over other processes, such as those based on arc welding. In particular, heat input and distortion are low, and the sophisticated systems to accurately control the processing head to build up a deposit on the work piece give superb flexibility. For nickel alloys, the low heat input can prevent liquation cracking in the service exposed substrate and provide an enabling technology for significant life extension of damaged parts which might otherwise require replacement.
The main barrier to the wider implementation of laser based additive manufacture, is that engineers cannot easily design parts that are produced using these techniques because the mechanical properties and potential performance of the deposited metal are not fully understood. DMLD will only achieve its full potential when a link between the process parameters used, the microstructure created and the properties of the deposit is established, and can therefore be used for part design.
The work reported here was carried out as part of TWI’s Core Research Programme and assessed the performance of deposits of alloy 718 and established links between observed weld quality, detailed microstructure and mechanical test performance. Quantitative data was established, which can be used for modelling of the microstructural development of the direct metal leaser deposits, and to provide guidance for an effective strategy for DMLD additive manufacture and repair of alloy 718 and similar materials. The presentation will review the deposition parameters used, the quality of the deposits produced and their resultant tensile, fatigue and creep performance.
Summary: Direct metal laser deposition (DMLD) offers an increasingly attractive additive manufacturing/repair route that can offer advantages over other processes, such as those based on arc welding. In particular, heat input and distortion are low, and the sophisticated systems to accurately control the processing head to build up a deposit on the work piece give superb flexibility. For nickel alloys, the low heat input can prevent liquation cracking in the service exposed substrate and provide an enabling technology for significant life extension of damaged parts which might otherwise require replacement.
The main barrier to the wider implementation of laser based additive manufacture, is that engineers cannot easily design parts that are produced using these techniques because the mechanical properties and potential performance of the deposited metal are not fully understood. DMLD will only achieve its full potential when a link between the process parameters used, the microstructure created and the properties of the deposit is established, and can therefore be used for part design.
The work reported here was carried out as part of TWI’s Core Research Programme and assessed the performance of deposits of alloy 718 and established links between observed weld quality, detailed microstructure and mechanical test performance. Quantitative data was established, which can be used for modelling of the microstructural development of the direct metal leaser deposits, and to provide guidance for an effective strategy for DMLD additive manufacture and repair of alloy 718 and similar materials. The presentation will review the deposition parameters used, the quality of the deposits produced and their resultant tensile, fatigue and creep performance.
