Changes in mechanical properties of heat resisting alloy for a satellite propulsion system after a nitriding process

Hideshi Kagawa, Go Fujii, Kenichi Kajiwara, Daisuke Kuroda, Takuya Suzuki, Yoko Yamabe-Mitarai, Hideyuki Murakami, Yoshinori Ono

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Haynes25 (L-605) is a common heat resistant alloy used in mono-propellant structures and screen materials for catalyst beds. The lifetime requirements for thrusters have expanded dramatically after studies conducted in the 1970s on mono-propellant materials used to extend the service life. The material design had long remained unchanged, and the L-605 was still used as thruster material due to its good heritage. However, some important incidents involving degradation were found during the test-unit break-up inspection following the thruster life tests. The Japanese research team focused on the L-605 degradations found on the catalyst bed screen mesh used for mono-propellant thruster and analysed the surface of the wire material and the cross-section of the wire screen mesh used in the life tests. The investigation showed that the degradation was caused by nitriding L-605 component elements. The team suggested that the brittle fracture was attributable to tungsten (W) carbides, which formed primarily in the grain boundaries, and chromium (Cr) nitride, which formed mainly in the parts in contact with the hot firing gas. The team also suggested the installation of a platinum coating on the material surface as a countermeasure L-605 nitric degradation. Inconel 625 is now selected as a mono-propellant structure material due to its marginal raw material characters and cost. The team believes that Inconel 625 does not form W carbides since it contains no tungsten component, but does contain Cr and Fe, which form nitrides easily. Therefore, the team agreed that for the Inconel 625, there was a need to evaluate changes in the microstructure and mechanical properties following exposure to hot nitrogen gases. This paper will describe these changes of Inconel 625.

Original languageEnglish
Title of host publicationProceedings of 12th European Conference on Spacecraft Structures, Materials and Environmental Testing
Publication statusPublished - 2012 Dec 19
Event12th European Conference on Spacecraft Structures, Materials and Environmental Testing - Noordwijk, Netherlands
Duration: 2012 Mar 202012 Mar 23

Publication series

NameEuropean Space Agency, (Special Publication) ESA SP
Volume691 SP
ISSN (Print)0379-6566

Other

Other12th European Conference on Spacecraft Structures, Materials and Environmental Testing
CountryNetherlands
CityNoordwijk
Period12/3/2012/3/23

ASJC Scopus subject areas

  • Aerospace Engineering
  • Space and Planetary Science

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  • Cite this

    Kagawa, H., Fujii, G., Kajiwara, K., Kuroda, D., Suzuki, T., Yamabe-Mitarai, Y., Murakami, H., & Ono, Y. (2012). Changes in mechanical properties of heat resisting alloy for a satellite propulsion system after a nitriding process. In Proceedings of 12th European Conference on Spacecraft Structures, Materials and Environmental Testing (European Space Agency, (Special Publication) ESA SP; Vol. 691 SP).