Femtosecond Laser-Based Additive Manufacturing: Current Status and Perspectives

Abstract

The ever-growing interest in additive manufacturing (AM) is evidenced by its extensive utilisation to manufacture a broad spectrum of products across a range of industries such as defence, medical, aerospace, automotive, and electronics. Today, most laser-based AM is carried out by employing continuous-wave (CW) and long-pulsed lasers. The CW and long-pulsed lasers have the downside in that the thermal energy imparted by the laser diffuses around the irradiated spot and often leads to the creation of heat-affected zones (HAZs). Heat-affected zones may degrade the material strength by producing micro-cracks, porous structures and residual stresses. To address these issues, currently, attempts are being made to employ ultrafast laser sources, such as femtosecond (fs) lasers, in AM processes. Femtosecond lasers with pulse durations in the order of 10−15 s limit the destructive laser–material interaction and, thus, minimise the probability of the HAZs. This review summarises the current advancements in the field of femtosecond laser-based AM of metals and alloys. It also reports on the comparison of CW laser, nanosecond (ns)/picosecond (ps) lasers with fs laser-based AM in the context of heat-affected zones, substrate damage, microstructural changes and thermomechanical properties. To shed light on the principal mechanisms ruling the manufacturing processes, numerical predictions are discussed and compared with the experimental results. To the best of the authors’ knowledge, this review is the first of its kind to encompass the current status, challenges and opportunities of employing fs lasers in additive manufacturing.

Study of the Processing Conditions for Stainless Steel Additive Manufacturing Using Femtosecond Laser

“…Finally, it is worth mentioning the remarkable variations in processing parameters that can be found in literature regarding the processing of metallic powder with UPS lasers, while in standard AM manufacturing they tend to be quite constant. The main reason for this is that, as two new parameters such as pulse repetition and pulse duration are added to the process, multiple possibilities arise in terms of parameter combinations for each material [64].…”

“…These studies demonstrate that it is possible to melt various kinds of materials when laser pulses are consecutive enough, accumulating heat and increasing the temperature up to the melting threshold. Interestingly, to our knowledge, no studies have been carried out on stainless steel by any other author [64].…”

Advancements in Laser and Ultrasound Therapeutic Strategies for Cancer Cells: Recent Review

“…As the pulse duration shortens, the energy and ablation depth rise, while heat diffusion length shortens, and a specifically defined ablation area is ablated without injuring the surrounding tissue, as shown in Fig. 2 [29].…”

Fabrication of Thin-Wall Structures with a Femtosecond Laser and Stainless Steel Powder

“…Despite this, and compared to them, USP lasers bring more precise heat accumulation control, leading to a more flexible melt pool; thus, higher spatial resolution is achieved, permitting the fabrication of thinner and more complex structures [7]. Moreover, additive manufacturing studies with femtosecond lasers are small [8], and even smaller with stainless steel powder, so this study analyses a field still unexplored.…”