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Cryogenic and hybrid induction-assisted machining strategies as alternatives for conventional machining of refractory tungsten and niobium

Olsson, Mike LU orcid ; Akujärvi, Ville LU and Bushlya, Volodymyr LU (2021) In International Journal of Refractory Metals and Hard Materials 97.
Abstract
Tungsten (W) and niobium (Nb) belong to the refractory metal group and are used as alloying elements in steels and superalloys for high demand products. These metals are also used in a high purity single-phase state for products within nuclear, space, military and research facilities.

In the current study, tool wear development and surface quality at different cutting conditions have been evaluated when machining high purity W 99.95% and Nb 99.7% in longitudinal turning. Cryogenic LN2 cooling and hybrid induction-assisted machining strategies were applied in order to alter W and Nb material state with respect to the ductile-to-brittle transformation temperature, and thus to attempt controlling their machinability. These advanced... (More)
Tungsten (W) and niobium (Nb) belong to the refractory metal group and are used as alloying elements in steels and superalloys for high demand products. These metals are also used in a high purity single-phase state for products within nuclear, space, military and research facilities.

In the current study, tool wear development and surface quality at different cutting conditions have been evaluated when machining high purity W 99.95% and Nb 99.7% in longitudinal turning. Cryogenic LN2 cooling and hybrid induction-assisted machining strategies were applied in order to alter W and Nb material state with respect to the ductile-to-brittle transformation temperature, and thus to attempt controlling their machinability. These advanced machining strategies were benchmarked against the more conventional machining solutions of dry, flood and high pressure cooling.

It was found that the use of LN2 cooling demonstrated the best result in terms of tool life when machining W followed by induction-assisted heating, dry and flood. All machining strategies provided similar surface quality which is related to strong build-up edge formation and respective surface alteration. When machining Nb, high pressure coolant results in best performance in terms of tool life and surface quality, then followed by flood and cryogenic strategies. Overall, substantial improvement of surface quality (Ra = 0.4–0.6 μm) was observed for high cutting speeds vc ≥ 225 m/min. (Less)
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author
; and
contributor
LU
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
International Journal of Refractory Metals and Hard Materials
volume
97
article number
105520
publisher
Elsevier
external identifiers
  • scopus:85102354347
ISSN
0263-4368
DOI
10.1016/j.ijrmhm.2021.105520
language
English
LU publication?
yes
id
45bae72a-3d66-4cd3-ab49-42eee76ac25f
date added to LUP
2021-03-15 15:01:24
date last changed
2023-11-21 00:45:03
@article{45bae72a-3d66-4cd3-ab49-42eee76ac25f,
  abstract     = {{Tungsten (W) and niobium (Nb) belong to the refractory metal group and are used as alloying elements in steels and superalloys for high demand products. These metals are also used in a high purity single-phase state for products within nuclear, space, military and research facilities.<br/><br/>In the current study, tool wear development and surface quality at different cutting conditions have been evaluated when machining high purity W 99.95% and Nb 99.7% in longitudinal turning. Cryogenic LN2 cooling and hybrid induction-assisted machining strategies were applied in order to alter W and Nb material state with respect to the ductile-to-brittle transformation temperature, and thus to attempt controlling their machinability. These advanced machining strategies were benchmarked against the more conventional machining solutions of dry, flood and high pressure cooling.<br/><br/>It was found that the use of LN2 cooling demonstrated the best result in terms of tool life when machining W followed by induction-assisted heating, dry and flood. All machining strategies provided similar surface quality which is related to strong build-up edge formation and respective surface alteration. When machining Nb, high pressure coolant results in best performance in terms of tool life and surface quality, then followed by flood and cryogenic strategies. Overall, substantial improvement of surface quality (Ra = 0.4–0.6 μm) was observed for high cutting speeds vc ≥ 225 m/min.}},
  author       = {{Olsson, Mike and Akujärvi, Ville and Bushlya, Volodymyr}},
  issn         = {{0263-4368}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{International Journal of Refractory Metals and Hard Materials}},
  title        = {{Cryogenic and hybrid induction-assisted machining strategies as alternatives for conventional machining of refractory tungsten and niobium}},
  url          = {{http://dx.doi.org/10.1016/j.ijrmhm.2021.105520}},
  doi          = {{10.1016/j.ijrmhm.2021.105520}},
  volume       = {{97}},
  year         = {{2021}},
}