ISSN:
1573-4889
Schlagwort(e):
surface carbides
;
Fe-Ni-Cr alloys
;
sulfur effects
;
morphology
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
Notizen:
Abstract The influence of sulfur upon surface carbide formation on a range of Fe-Ni-Cr alloys has been investigated at a temperature of 1273 K. The addition of small amounts of H2S, up to 100 ppm (range of $$p_{S_2 } $$ = 2.2×10−12 to 5.5×10 su−11 bar), to a H2-CH4 carburizing atmosphere (ac=0.8) was found to significantly modify the behavior from that normally observed in the sulfur-free environment. The carburization of these alloys in the H2-CH4 atmosphere led to the formation of globular particles of M7C3 on the surface of the alloy, but the addition of H2S affected the type, morphology, and distribution of the surface carbides. Initially, the lower carbon containing M23C6 was formed, which transformed to M7C3 at a rate determined by the concentration of sulfur in the environment. The morphology of the M7C3 was modified by the presence of sulfur, and the carbide exhibited a preferred crystallographic orientation in the [001] direction. Particles of manganese sulfide were formed on the commercial alloys at $$p_{S_2 } $$ 〉 2.3 × 10−11 bar at 1273 K, and these served as nucleation sites for carbides sothat, in contrast to the behavior in sulfur-free conditions, complete surfacecarbide layers were formed.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00659598
