Figure 3 presents SEM micrographs of the cross-section of carburized
18CrNiMo7-6 steel after shot peening treatment.
The couple made of carburized
18CrNi4A (number 5 couple) possesses lower wear coefficient of 8.84 x [10.sup.-9] [KPa.sup.-1] after 120 min testing.
-grinding of the overlaps, but then the thickness of carburized
layer is declined;
section will have carbon content high enough so that it can be hardened again through flame or induction hardening.
As a result, the upper surfaces of the casting, which are in contact with the mold for only a short period of time due to volumetric contract during solidification and cooling, are less likely to be carburized
. The lower surfaces of the casting, which are in continual contact with the mold during cooling, are more likely to be affected by carbon migration.
Specifications for carburized
parts in current aerospace gearing materials include cryogenic treatments that improve dimensional stability, minimize retained austenite levels, increase surface hardness, and improve wear properties.
and tempered specimen shows a better result of 950*[10.sup.3] cycles for 200 MPa, whereas the carburized
and austenized specimen resulted for 702*[10.sup.3] cycles.
Specific topics include interaction between liquid magnesium alloy and glassy carbon particles, the effect of pre-treatment on the corrosion resistance of superheated materials, and the effect of process temperature on the surface layer of vacuum carburized
low-alloy steel gears.
In comparison with bearings made of ordinary carburized
steel, Super-TF material offers up to 10 times the life with contaminated lubrication and up to twice the life where the lubricant is clean.
Sometimes refrigeration is applied between quenching and tempering on purpose to avoid coming of the retained austenite in the carburized
Volume II covers physical metallurgy and alloy design, with papers on calculation of steel microstructure for strong alloys, ductility of advanced bainitic steels, local deformation behavior of high-strength PM-tool steels, and microstructural control and properties in Nb-modified carburized