Study On Microstructure Evolution And Mechanical Response Of CLAM Steel Irradiated By Hiah Energy Helium On

Low activation martensitic steel is regarded as the preferred structural material for future fusion demonstration reactor and fusion power reactor due to its low irradiation swelling,thermal expansion coefficient,high thermal conductivity and low activation after irradiation.The blanket structural material of fusion reactor will be exposed to high-energy neutron and ion irradiation during service.The microstructure of martensitic steel changes after irradiation,which leads to the reduction of mechanical properties.This will lead to the structural damage of the components and cause major safety accidents and economic losses.Studying the microstructure and mechanical behavior evolution of low activation martensite steel under irradiation environment can provide a theoretical basis for the optimization design of radiation resistance and the safety assessment of the material during service.In this paper,the microstructure evolution and mechanical response changes of China Low Activation Martensitic(CLAM)steel with Chinese independent intellectual property rights before and after high-energy helium ion irradiation were studied.The main research contents are as follows:(1)Study on irradiation damage dose of CLAM steel after high energy helium ion irradiation The motion trajectory,range and concentration distribution of helium ion after vertical incidence into CLAM steel were obtained by The Stopping and Range of Ions in Matter(SRIM)simulation software.And the displacement per atom distribution in CLAM steel was also calculated.The effects of different energy and dose of helium ion irradiation on the distribution of helium ion concentration in CLAM steel and the depth and width of irradiation damage layer in CLAM steel were studied.(2)Study on microstructure evolution of CLAM steel before and after high energy helium ion irradiationThe microstructure of CLAM steel before and after irradiation was characterized by transmission electron microscope(TEM).The size of precipitates in CLAM steel after highenergy helium ion irradiation was analyzed.The density and size of helium bubbles and dislocation loops in CLAM steel specimens with different irradiation doses were counted.Combined with microstructure analysis,mechanism of crack nucleation in CLAM steel during compression is established.(3)Study on mechanical response changes of CLAM steel before and after high energy helium ion irradiationThe load-displacement curves of CLAM steel in tension and compression before and after irradiation were obtained by macro tension,microcolumn compression and nanoindentation experiments.The effects of high-energy helium ion irradiation on the yield strength and hardness of CLAM steel were analyzed,and the mathematical model of hardness change with irradiation dose was established.The effect of microscopic defect size and concentration on macroscopic irradiation hardening was investigated by the Dispersed-Barrier Hardening(DBH)model and Friedel-Kroupa-Hirsch(FKH)model.