Abstract
This study investigates the influence of resistive pre-heating of the feedstock wire (here called hot-wire) on the stability of laser-directed energy deposition of Duplex stainless steel. Data acquired online during depositions as well as metallographic investigations revealed the process characteristic and its stability window. The online data, such as electrical signals in the pre-heating circuit and images captured from side-view of the process interaction zone gave insight on the metal transfer between the molten wire and the melt pool. The results show that the characteristics of the process, like laser-wire and wire-melt pool interaction, vary depending on the level of the wire pre-heating. In addition, application of two independent energy sources, laser beam and electrical power, allows fine-tuning of the heat input and increases penetration depth, with little influence on the height and width of the beads. This allows for better process stability as well as elimination of lack of fusion defects. Electrical signals measured in the hot-wire circuit indicate the process stability such that the resistive pre-heating can be used for in-process monitoring. The conclusion is that the resistive pre-heating gives additional means for controlling the stability and the heat input of the laser-directed energy deposition.
Highlights
Directed energy deposition (DED) is one category of additive manufacturing (AM) in which materials are melted by focused thermal energy during deposition [1]
To understand the influence of the hot-wire on the Laser-directed energy deposition with wire (LDEDw) process, the monitoring data and the data obtained from the metallographic investigation were analyzed
This study investigated the process of Laser-Directed Energy Deposition of a Duplex stainless steel wire pre-heated by an electric current flowing through it
Summary
Directed energy deposition (DED) is one category of additive manufacturing (AM) in which materials are melted by focused thermal energy during deposition [1]. The major advantage of the wire-feed DED processes is material’s usage efficiency, which reaches up to 100% [2]. This makes them suitable for production of large-scale components in high volume. The wire-feed DED has begun to replace conventional, subtractive machining in various applications where the costs associated with material consumption are considerably high. An increased interest in the use of the wire-feed DED for processing of high temperature and corrosion resistant metals, like stainless steels [6,7,8], Nickel [8,9,10,11] and Titanium-based [12,13] alloys, is being observed
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