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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2020, Vol. 41 ›› Issue (10): 423709-423709.doi: 10.7527/S1000-6893.2020.23709

• Material Engineering and Mechanical Manufacturing • Previous Articles    

Dynamic mechanical behavior and failure model of 38CrMoAl steel under high strain rate

CHEN Yueliang1, ZHANG Zhuzhu1, BIAN Guixue1, ZHANG Yong1, HUANG Hailiang1,2   

  1. 1. Naval Aviation University Qingdao Campus, Qingdao 266041, China;
    2. Naval Aviation University Aviation Support Professional Training Base, Qingdao 266041, China
  • Received:2019-12-04 Revised:2020-02-04 Published:2020-02-21
  • Supported by:
    National Natural Science Foundation of China (51375490); China Postdoctoral Science Foundation (2019M653929)

Abstract: 38CrMoAl steel is the main material of an aircraft structure frequently subjected to impact loads. To obtain the mechanical behavior and failure parameters of the steel under impact loads, a quasi-static test, a dynamic mechanical test of strain rates from 650 s-1 to 5 500 s-1 and a stress triaxiality test were conducted on 38CrMoAl steel. The microstructure and fracture morphology of the material were microscopically observed and analyzed. Finally, the modified strength model and failure model parameters of the material were determined based on the test results. The test results show that 38CrMoAl steel has strong strain rate sensitivity. The yield strength of the material has a positive strain rate strengthening effect as the strain rate increases. When the strain rate changes from 10-3 s-1 to 5 500 s-1, the yield stress rises from 450 MPa to 1 085 MPa. When the strain rate is 5 500 s-1, the yield stress of the material reaches 2.41 times that under quasi-static conditions. The microscopic observation and analysis of the material structure disclosed that the material is mainly composed of grained tempered sorbite, the plasticity of the material decreases under high strain rate loading, and the fracture is transformed from a plastic dimple-type fracture to a local cleavage one. The litter size also decreases with the increasing strain rate. The strain rate strengthening term in the Johnson-Cook (J-C) strength model was modified to enable the modified constitutive model to more effectively describe the dynamic mechanical behavior of 38CrMoAl steel. Finally the J-C failure criterion parameters of the material were determined.

Key words: 38CrMoAl, dynamic mechanical properties, high strain rate, Hopkinson bar, modified J-C constitutive, failure parameters

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