scholarly journals Review of Laser Powder Bed Fusion of Gamma-Prime-Strengthened Nickel-Based Superalloys

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 996
Author(s):  
Olutayo Adegoke ◽  
Joel Andersson ◽  
Håkan Brodin ◽  
Robert Pederson

This paper reviews state of the art laser powder bed fusion (L-PBF) manufacturing of γ′ nickel-based superalloys. L-PBF resembles welding; therefore, weld-cracking mechanisms, such as solidification, liquation, strain age, and ductility-dip cracking, may occur during L-PBF manufacturing. Spherical pores and lack-of-fusion voids are other defects that may occur in γ′-strengthened nickel-based superalloys manufactured with L-PBF. There is a correlation between defect formation and the process parameters used in the L-PBF process. Prerequisites for solidification cracking include nonequilibrium solidification due to segregating elements, the presence of liquid film between cells, a wide critical temperature range, and the presence of thermal or residual stress. These prerequisites are present in L-PBF processes. The phases found in L-PBF-manufactured γ′-strengthened superalloys closely resemble those of the equivalent cast materials, where γ, γ′, and γ/γ′ eutectic and carbides are typically present in the microstructure. Additionally, the sizes of the γ′ particles are small in as-built L-PBF materials because of the high cooling rate. Furthermore, the creep performance of L-PBF-manufactured materials is inferior to that of cast material because of the presence of defects and the small grain size in the L-PBF materials; however, some vertically built L-PBF materials have demonstrated creep properties that are close to those of cast materials.

2021 ◽  
pp. 109895
Author(s):  
Ashutosh Jena ◽  
Sila Ece Atabay ◽  
Alexandre B. Gontcharov ◽  
Paul Lowden ◽  
Mathieu Brochu

Author(s):  
Alex Matos da Silva Costa ◽  
João Pedro Oliveira ◽  
André Luiz Jardini Munhoz ◽  
Eduardo Guimarães Barbosa Leite ◽  
Denise Souza de Freitas ◽  
...  

2019 ◽  
Vol 3 (3) ◽  
pp. 75
Author(s):  
Alena Kreitcberg ◽  
Karine Inaekyan ◽  
Sylvain Turenne ◽  
Vladimir Brailovski

The microstructure and mechanical properties of IN625 alloy processed by laser powder bed fusion (LPBF) and then subjected to stress relief annealing, high temperature solution treatment, and hot isostatic pressing were studied. Tensile testing to failure was carried out in the 25–871 °C temperature range. Creep testing was conducted at 760 °C under 0.5–0.9 yield stress conditions. The results of the present study provided valuable insights into the static and creep properties of LPBF IN625 alloy, as compared to a wrought annealed alloy of similar composition. It was shown that at temperatures below 538 °C, the mechanical resistance and elongation to failure of the LPBF alloy were similar to those of its wrought counterpart, whereas at higher temperatures, the elongation to failure of the LPBF alloy became significantly lower than that of the wrought alloy. The solution-treated LPBF alloy exhibited significantly improved creep properties at 760 °C as compared to the wrought annealed alloy, especially under intermediate and low levels of stress.


2019 ◽  
Vol 10 (1) ◽  
pp. 81 ◽  
Author(s):  
Zhihua Tian ◽  
Chaoqun Zhang ◽  
Dayong Wang ◽  
Wen Liu ◽  
Xiaoying Fang ◽  
...  

The Inconel 625 (IN625) superalloy has a high strength, excellent fatigue, and creep resistance under high-temperature and high-pressure conditions, and is one of the critical materials used for manufacturing high-temperature bearing parts of aeroengines. However, the poor workability of IN625 alloy prevents IN625 superalloy to be used in wider applications, especially in applications requiring high geometrical complexity. Laser powder bed fusion (LPBF) is a powerful additive manufacturing process which can produce metal parts with high geometrical complexity and freedom. This paper reviews the studies that have been done on LPBF of IN625 focusing on the microstructure, mechanical properties, the development of residual stresses, and the mechanism of defect formation. Mechanical properties such as microhardness, tensile properties, and fatigue properties reported by different researchers are systematically summarized and analyzed. Finally, the remaining issues and suggestions on future research on LPBF of IN625 alloy parts are put forward.


Author(s):  
Sarini Jayasinghe ◽  
Paolo Paoletti ◽  
Chris Sutcliffe ◽  
John Dardis ◽  
Nick Jones ◽  
...  

AbstractWhile Laser powder bed fusion (L-PBF) machines have greatly improved in recent years, the L-PBF process is still susceptible to several types of defect formation. Among the monitoring methods that have been explored to detect these defects, camera-based systems are the most prevalent. However, using only photodiode measurements to monitor the build process has potential benefits, as photodiode sensors are cost-efficient and typically have a higher sample rate compared to cameras. This study evaluates whether a combination of photodiode sensor measurements, taken during L-PBF builds, can be used to predict measures of the resulting build quality via a purely data-based approach. Using several unsupervised clustering approaches build density is classified with up to 93.54% accuracy using features extracted from three different photodiodes, as well as observations relating to the energy transferred to the material. Subsequently, a supervised learning method (Gaussian Process regression) is used to directly predict build density with a RMS error of 3.65%. The study, therefore, shows the potential for machine-learning algorithms to predict indicators of L-PBF build quality from photodiode build measurements only. This study also shows that, relative to the L-PBF process parameters, photodiode measurements can contribute to additional information regarding L-PBF part quality. Moreover, the work herein describes approaches that are predominantly probabilistic, thus facilitating uncertainty quantification in machine-learnt predictions of L-PBF build quality.


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