Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear
Journal article, 2024

Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

Alloy 718

Tool wear

Additive manufacturing

Surface integrity

Machining

Author

Jonas Holmberg

RISE Research Institutes of Sweden

Johan C Berglund

RISE Research Institutes of Sweden

Ulrika Brohede

Swerim AB

Pia Åkerfeldt

Luleå University of Technology

Viktor Sandell

Luleå University of Technology

Amir Rashid

Royal Institute of Technology (KTH)

Xiaoyu Zhao

Royal Institute of Technology (KTH)

Sasan Dadbakhsh

Royal Institute of Technology (KTH)

Marie Fischer

Chalmers, Industrial and Materials Science, Materials and manufacture

Eduard Hryha

Chalmers, Industrial and Materials Science, Materials and manufacture

U. Wiklund

Uppsala University

Carl Johan Karlsson Hassila

Uppsala University

Seyed B. Hosseini

RISE Research Institutes of Sweden

International Journal of Advanced Manufacturing Technology

0268-3768 (ISSN) 1433-3015 (eISSN)

Vol. 130 3-4 1823-1842

Subject Categories

Manufacturing, Surface and Joining Technology

DOI

10.1007/s00170-023-12727-w

More information

Latest update

1/25/2024