Mechanical properties of molybdenum alloys micro-structurally controlled by internal nitriding

Citation
M. Nagae et al., Mechanical properties of molybdenum alloys micro-structurally controlled by internal nitriding, J JPN METAL, 64(9), 2000, pp. 751-754
Citations number
8
Categorie Soggetti
Metallurgy
Journal title
JOURNAL OF THE JAPAN INSTITUTE OF METALS
ISSN journal
00214876 → ACNP
Volume
64
Issue
9
Year of publication
2000
Pages
751 - 754
Database
ISI
SICI code
0021-4876(200009)64:9<751:MPOMAM>2.0.ZU;2-0
Abstract
Internally nitrided dilute Mo-Ti alloys having a heavily deformed microstru cture near the specimen surface were prepared by a novel two-step nitriding ; process at 1173 to 1773 K in N-2 gas. For the nitrided specimens, three-p oint bend tests were performed at temperatures from 77 to 298 K in order to investigate the effect of microstructure control by internal nitriding on the ductile-brittle transition temperature (DBTT) of the alloy. Yield stren gth obtained at 243 K of the specimen maintaining the deformed microstructu re by the two-step nitriding was about 1.7 times as much as recrystallized specimen. The specimen subjected to the two-step nitriding was bent more th an 90 degree at 243 K, whereas recrystallized specimen was fractured after showing a slight ductility at 243 K. DBTT of the specimen subjected to the two-step nitriding and recrystallized specimen was about 153 K and 203 K, r espectively. These results indicate that multi-step internal nitriding is v ery effective to the improvement in the embrittlement by the recrystallizat ion of molybdenum alloys.