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Abstract: The
dissipated heat in grinding is utilized to induce martensitic phase
transformation and strengthen the surface layer of 40Cr steel by raising
surface temperature higher than austenic temperature and cooling
quickly. The experiment of grinding 40Cr steel is taken in grinding
machine. The metallurgical microstructure, depth and hardness of
transect phase transformation layer are analyzed and surface roughness
is measured. Temperature field and temperature history are simulated
based on finite element method. The simulated hardness penetration depth
is deduced from every place temperature history of work piece and
martensitic phase transformation conditions. The experiment result shows
that martensitic phase transformation takes place on the 40Cr steel
surface layer in grinding, the hardness of surface layer is improved
highly and surface roughness accords with the roughness of traditional
grinding. So, it is possible for grind-hardening to take place of
induction hardening. The temperature field and history can be simulated
based on finite element method to predict the hardness penetration depth
and optimize the grinding parameters. Thus the experiment cost and time
can be reduced.
Key words: Grind-hardening
Surface phase transformation Temperature field simulation
CLC No: TG58
山东省自然科学基金资助项目(Y2002F05).Received 20050531,received in revised form
20060209 |