| AISI420 martensitic stainless steel and AISI5140 alloy steel are the most commonly used metal materials for the mechanisms or structures currently used in the manufacture of spacecraft.When a spacecraft is in space service,most of the aerospace components are usually placed outside the spacecraft cabin,such as extension mechanisms,brakes,compression release mechanisms,hinge mechanisms,and so on.Since these mechanisms require exercise,it is difficult to add protective devices to the outside.Therefore,it is inevitable that it will be irradiated by charged particles.Among them,the effect of proton irradiation on the microstructure and mechanical properties of AISI420 martensitic stainless steel and 5140 alloy steel and the degree of damage need to be characterized and evaluated.Based on the above reasons,the AISI420 martensitic stainless steel and 5140 alloy steel were used as research objects,and the proton irradiation experiment of simulated space environment was carried out using the positive ion irradiation simulation test instrument of Harbin Institute of Technology.The AISI420 martensitic stainless steels annealed,600 °C and 700 °C tempered and 5140 tempered at 480 °C,520 °C and 560 °C were investigated for proton irradiation in three different cumulative fluences.After that,its microstructure,macroscopic mechanical properties and evolution of nanomechanical properties and its mechanism of action.The effects of heat treatment and proton irradiation on the phase composition of the two steel phases were analyzed by X-ray diffraction.The effects of heat treatment and proton irradiation on the microstructure evolution of the two steel surface layers were analyzed by transmission electron microscopy.The macroscopic mechanical properties of the two steels were tested by Instron5982 universal material testing machine.The fracture morphology and fracture mechanism of the two steels were analyzed by KYKY-2800 B scanning electron microscope.The effects and effects of quenching and tempering heat treatment and proton irradiation on the nanomechanical behavior and nanoscratch friction behavior of the two steels were investigated by Tribo Indenter nanoindenter.The results showed that there was no new phase after AISI 420 martensitic stainless steel and 5140 alloy steel have been irradiated by protons with different cumulative fluences.The mechanical tensile test shows that the macroscopic tensile strength of the two steels increases slightly with the increase of the cumulative fluence of proton irradiation.Through TEM analysis,it was found that different tempering temperatures caused the grain size of the two steels to change,the grain size increased with the tempering temperature.The effects of proton irradiation on the microstructure of the two steels show that the proton irradiation leads to the evolution of the microstructure of the two steels.The surface damage of the surface layers of AISI 420 martensitic stainless steel and 5140 alloy steel is induced by irradiation damage.The defect of the structure,the formation of a large number of vacancies and dislocation loops,the dislocation configuration and the dislocation density in the surface layer microstructure change,and the dislocation density increases with the increase of the cumulative fluence of proton irradiation.Nanoindentation and nanoscratch experiments show that proton irradiation has little effect on the nanoelastic modulus of AISI 420 martensitic stainless steel and 5140 alloy steel,but has a certain effect on nanohardness.The nanoindentation hardness of AISI 420 martensitic stainless steel and 5140 alloy steel increases with the increase of the cumulative fluence of proton irradiation,and the change of the maximum residual indentation depth is reversed.The reason was due to the surface hardening effect produced by proton irradiation.The surface hardening effect of proton irradiation with different cumulative fluences has a certain effect on the nanoscratch hardness and nano-friction properties of AISI 420 martensitic stainless steel.With the increase of the cumulative fluence of proton irradiation,the hardness of nano-scratches increased has led to a decrease in the nano-coefficient of friction and a reduction in the wear volume and wear rate. |
PDF Full Text Request