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EFFECT OF GROUND LAYER ON ULTRA LONG
LIFE FATIGUE BEHAVIOUR IN HIGH CARBON
CHROMIUM BEARING STEEL
LU Liantao1 SHIOZAWA Kazuaki2
NISHINO Seiichi2
(1. State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 6l0031;
2. Faculty of Engineering, Toyama University, Toyama 930-8555, Japan
)
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Abstract: In
order to investigate the effect of ground layer on fatigue behavior of
high carbon chromium bearing steel JIS SUJ2 in ultra-long life regime, rotating-bending fatigue tests are performed in laboratory air at room
temperature using hour- glass-shaped emerized and electro-polished
specimens. The emerized specimen and the electro-polished one are
obtained by removing a partial ground layer with surface roughness and
the whole ground layer from ground ones, respectively. The results show
that S-N curves are composed of surface fracture mode curve in the
region of short life and internal fracture mode curve in the region of
long life. The S-N curves for surface fracture mode are affected by
surface roughness and compressive residual stress. The S-N curves for
internal fracture mode are not affected by surface conditions, which is
an inherent characteristic of the material. For the surface fracture
mode, the emerized specimen shows the largest fatigue limit, about 1.11
times larger than for the electro-polished one and 1.20 times larger
than for the ground one. The fatigue limits of surface fracture mode
affected by the surface compressive residual stress can be expressed by
modified Goodman diagram. Furthermore, conditions for internal crack
initiation and propagation are discussed. The fatigue limit in
ultra-long life regime is estimated.
Key words: Ultra-long life fatigue Ground layer S-N curve
Surface crack Internal crack
Nonmetallic inclusion Fish-eye Bearing steel
CLC No: TG113
国家自然科学基金资助项目(50471047, 50323003). Received 20060209, rreceived in revised form 20060928
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