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Simulation of Impact Toughness with the Effect of Temperature and Irradiation in Steels
Chenchong Wang,Jinliang Wang,Yuhao Li,Chi Zhang,Wei Xu 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1
One of the important requirements for the application of reduced activation ferritic/martensitic steel is toretain proper mechanical properties in irradiation and high temperature conditions. In order to simulatethe impact toughness with the effect of temperature and irradiation, a simulation model based on energybalance method consisted of crack initiation, plastic propagation and cleavage propagation stages wasestablished. The effect of temperature on impact toughness was analyzed by the model and the trend ofthe simulation results was basicly consistent with the previous experimental results of CLAM steels. Theload-displacement curve was simulated to express the low temperature ductile-brittle transition. Theeffect of grain size and inclusion was analyzed by the model, which was consistent with classicalexperiment results. The transgranular-intergranular transformation in brittle materials was alsosimulated.
Wang, Chenchong,Shen, Chunguang,Huo, Xiaojie,Zhang, Chi,Xu, Wei Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.5
In order to make reasonable design for the improvement of comprehensive mechanical properties of RAFM steels, the design system with both machine learning and high-throughput optimization algorithm was established. As the basis of the design system, a dataset of RAFM steels was compiled from previous literatures. Then, feature engineering guided random forests regressors were trained by the dataset and NSGA II algorithm were used for the selection of the optimal solutions from the large-scale solution set with nine composition features and two treatment processing features. The selected optimal solutions by this design system showed prospective mechanical properties, which was also consistent with the physical metallurgy theory. This efficiency design mode could give the enlightenment for the design of other metal structural materials with the requirement of multi-properties.
Sinan Zhu,Chi Zhang,Zhigang Yang,Chenchong Wang 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.8
Reduced activation ferritic/martensitic (RAFM) steels are widely applied as structural materials in thenuclear industry. To investigate hydrogen's effect on RAFM steels' elastic properties and the mechanismof that effect, a procedure of first principles simulation combined with experiment was designed. Densityfunctional theory models were established to simulate RAFM steels' elastic status before and after hydrogen'sinsertion. Also, experiment was designed to measure the Young's modulus of RAFM steelsamples with and without hydrogen charging. Both simulation and experiment showed that the solubilityof hydrogen in RAFM steels would decrease the Young's modulus. The effect of hydrogen on RAFMsteels' Young's modulus was more significant in water-quenched steels than it was in tempering steels. This indicated that defects inside martensite, considered to be hydrogen traps, could decrease thecohesive energy of the matrix and lead to a decrease of the Young's modulus after hydrogen insertion.