Papers by Author: Hui Li

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Authors: Ming Pang, Hui Li, Jian Song Tan, Guang Hui Xu, Quan Zhong Zhang
Abstract: Exploring experiments of the laser hardening valve seat of worm cast iron were conducted.Microstructure of laser hardening region was characterized by optical microscopy (OM). Mechanical properties of the hardening region were evaluated by hardness. Effect of laser hardening parameters on the valve seat of worm cast iron were discussed in detail. Results show that the harded region have non-equilibrium microstructures consisting of martensite and residual austenite with a little ferrite. Microstructure of the martensite shell around the worm graphite in the hardened zone is observed. With increasing defocusing distance ,the hardness of hardened region decrease.The hardness of hardened region can be increased by imporving laser power and reducing laser welding velocity.
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Authors: Bo Wu, Hui Li, Na Zou, Jian Song Tan, Ding Yun Hu
Abstract: A finite element model is developed in this paper for simulating cyclic deformation in ultra-fined polycrystalline metals. The grain material is characterized by conventional theory of mechanism-based strain gradient plasticity (CMSG). A cohesive interface model was used to simulate the initiation and propagation of intergranular cracks. The simulation results show that inhomogeneous plastic deformation induces high strain gradient effects and severely plastic hardening in the grain interior, and the intergranular crack has a significant influence on the overall mechanical properties of ultra-fined polycrystalline metals subjected to cyclic loading.
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