Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Degradation of multi-layer CVD-coated cemented carbide in finish milling compacted graphite iron

Lindvall, Rebecka LU ; Bello Bermejo, Juan Manuel LU orcid ; Cámara Herrero, Belén ; Sirén, Sebastian ; Magnusson Åberg, Lena ; Norgren, Susanne LU ; M'Saoubi, Rachid LU ; Bushlya, Volodymyr LU and Ståhl, Jan Eric LU (2023) In Wear 522.
Abstract

Stricter regulations on emissions and higher demands on engine performance drive automotive industries to replace conventional gray cast iron with compacted graphite iron (CGI). CGI has a higher wear resistance, strength, elastic modulus, and almost double fatigue strength as to gray cast iron, yet the same positive properties make CGI more difficult to machine. This study focuses on finish milling CGI EN-GJV-450 with current industrial standard of tooling: cemented carbide with multi-layer CVD-coating of Ti(C,N)–Al2O3. At cutting speed of 150 m/min a total of 3126 cm3 of material after 190 passes was removed, while 1645 cm3 was removed after 100 passes in case of 250 m/min. Studying the wear... (More)

Stricter regulations on emissions and higher demands on engine performance drive automotive industries to replace conventional gray cast iron with compacted graphite iron (CGI). CGI has a higher wear resistance, strength, elastic modulus, and almost double fatigue strength as to gray cast iron, yet the same positive properties make CGI more difficult to machine. This study focuses on finish milling CGI EN-GJV-450 with current industrial standard of tooling: cemented carbide with multi-layer CVD-coating of Ti(C,N)–Al2O3. At cutting speed of 150 m/min a total of 3126 cm3 of material after 190 passes was removed, while 1645 cm3 was removed after 100 passes in case of 250 m/min. Studying the wear evolution at different engagement times demonstrated an accelerated chemical wear of the Al2O3 top coating due to its reaction with MgO-containing inclusions that creates a softer reaction product of (Mg,Fe,Mn)Al2O4 spinel which is abraded and removed with the chip flow. Ti(C,N) coating layer experiences diffusional and mechanical (abrasion, debonding, micro-fracture) wear mechanisms. Exposure of cemented carbide substrate resulted in its rapid wear in the form of cratering and massive material loss on the flank where the latter eventually causes tool failure. The adherence of CGI to WC-Co facilitates diffusional loss of carbon and tungsten from WC grains. Carbon reacts with iron at the interface forming iron carbide, while residual tungsten alloys it thus forming (Fex,W1-x)3C. This phase can reduce the wear rate as it acts as a diffusion barrier, but its high brittleness enables its periodic removal by adhesive wear. Outward cobalt diffusion was also an active wear mechanism that facilitates further diffusion of carbon and tungsten but also weakens the WC-grain bonding, further facilitating adhesive wear by CGI flow. Deposition of oxide inclusions to exposed WC-Co work as an anti-stick for CGI adhesion and thus reduces the wear rate.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cemented carbide, CGI, CVD, Milling
in
Wear
volume
522
article number
204724
publisher
Elsevier
external identifiers
  • scopus:85151953436
ISSN
0043-1648
DOI
10.1016/j.wear.2023.204724
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2023 The Authors
id
33ef7d1f-0b70-4dd7-944a-b8d57b214795
date added to LUP
2023-04-24 21:04:29
date last changed
2024-03-08 00:21:04
@article{33ef7d1f-0b70-4dd7-944a-b8d57b214795,
  abstract     = {{<p>Stricter regulations on emissions and higher demands on engine performance drive automotive industries to replace conventional gray cast iron with compacted graphite iron (CGI). CGI has a higher wear resistance, strength, elastic modulus, and almost double fatigue strength as to gray cast iron, yet the same positive properties make CGI more difficult to machine. This study focuses on finish milling CGI EN-GJV-450 with current industrial standard of tooling: cemented carbide with multi-layer CVD-coating of Ti(C,N)–Al<sub>2</sub>O<sub>3</sub>. At cutting speed of 150 m/min a total of 3126 cm<sup>3</sup> of material after 190 passes was removed, while 1645 cm<sup>3</sup> was removed after 100 passes in case of 250 m/min. Studying the wear evolution at different engagement times demonstrated an accelerated chemical wear of the Al<sub>2</sub>O<sub>3</sub> top coating due to its reaction with MgO-containing inclusions that creates a softer reaction product of (Mg,Fe,Mn)Al<sub>2</sub>O<sub>4</sub> spinel which is abraded and removed with the chip flow. Ti(C,N) coating layer experiences diffusional and mechanical (abrasion, debonding, micro-fracture) wear mechanisms. Exposure of cemented carbide substrate resulted in its rapid wear in the form of cratering and massive material loss on the flank where the latter eventually causes tool failure. The adherence of CGI to WC-Co facilitates diffusional loss of carbon and tungsten from WC grains. Carbon reacts with iron at the interface forming iron carbide, while residual tungsten alloys it thus forming (Fe<sub>x</sub>,W<sub>1-x</sub>)<sub>3</sub>C. This phase can reduce the wear rate as it acts as a diffusion barrier, but its high brittleness enables its periodic removal by adhesive wear. Outward cobalt diffusion was also an active wear mechanism that facilitates further diffusion of carbon and tungsten but also weakens the WC-grain bonding, further facilitating adhesive wear by CGI flow. Deposition of oxide inclusions to exposed WC-Co work as an anti-stick for CGI adhesion and thus reduces the wear rate.</p>}},
  author       = {{Lindvall, Rebecka and Bello Bermejo, Juan Manuel and Cámara Herrero, Belén and Sirén, Sebastian and Magnusson Åberg, Lena and Norgren, Susanne and M'Saoubi, Rachid and Bushlya, Volodymyr and Ståhl, Jan Eric}},
  issn         = {{0043-1648}},
  keywords     = {{Cemented carbide; CGI; CVD; Milling}},
  language     = {{eng}},
  month        = {{06}},
  publisher    = {{Elsevier}},
  series       = {{Wear}},
  title        = {{Degradation of multi-layer CVD-coated cemented carbide in finish milling compacted graphite iron}},
  url          = {{http://dx.doi.org/10.1016/j.wear.2023.204724}},
  doi          = {{10.1016/j.wear.2023.204724}},
  volume       = {{522}},
  year         = {{2023}},
}