Research on Influences of Surface Roughness and Hardening Rate on Fatigue Property in DD5 Creep Feed Grinding
In order to study the influence laws and mechanism of surface roughness and hardening rate on fatigue property of DD5 nickel-based single crystal superalloy during creep feed grinding,the experiments were designed and tested.The results show that the increase of surface roughness leads to the aggravation of stress concentration and decrease of fatigue property.Under different grinding processes,when the value of surface roughness increases from 0.347 μm to 0.687 μm,the fatigue life decreases from 5.51×105 to 3.38×105,and the reduction rate is about 38.66％.When the value of surface roughness is less than 0.4 μm,the surface hardening may improve the fatigue life of the speci-men.When the value of surface roughness is more than 0.4 μm,the surface hardening has no signifi-cant effect on the fatigue property.The morphological tests show that with the increase of surface roughness,the number and depth of gullies generated by ploughing on the grinding surface increase,the number of crack sources on the grinding surface increases and the stress concentration intensifies under fatigue load,which leads to the decrease of fatigue life.Lower surface roughness and larger sur-face hardening rate may improve the creep feed grinding fatigue property of DD5.
DD5 super alloycreep feed grindingsurface roughnesssurface hardening ratefa-tigue propertyfracture mechanism
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