Supervisor:
Southwest Ordnance Industry Bureau
Organizer:
Chongqing Ordnance Industry Society
Chongqing University of Technology
Chongqing University of Technology
Study on hot compression properties of GH4720Li alloy at a high strain rate
| DOI: | 10.11809/bqzbgcxb2023.05.022 |
| Keywords: | GH4720Li alloy; Johnson Cook constitutive equation; dynamic mechanics; high strain rate; stress |
| Abstract: | In order to study the dynamic mechanical properties of nickel base superalloy GH4720Li at a high strain rate, this paper carries out uniaxial thermal compression tests to the materials with a Split Hopkinson Pressure Bar (SHPB) in a temperature range of 20 ℃ to 1 000 ℃ and a strain rate range of 10 s -1 to 5 000 s -1 . The stress strain curves of the materials at different temperatures and different strain rates are obtained. The results show that under the same test temperature, GH4720Li alloy shows different dynamic mechanical properties at a high and a low strain rates. At a low strain rate (10 s -1 ), the stress value of GH4720Li alloy decreases with the increase of temperature. Under the condition of a high strain rate (1 000 s -1 or 5 000 s -1 ), the stress value of GH4720Li alloy increases with the increase of temperature in a specific temperature range (400 ℃ to 800 ℃). Combined with the obtained test data, the original Johnson Cook (J C) constitutive equation is modified by the numerical fitting method to meet the stress variation law of GH4720Li alloy at a high strain rate. The accuracy of the modified J C constitutive equation is verified by linear correlation coefficient and mean error. The results show that the modified J C constitutive equation is in good agreement with the experimental data, which can greatly improve the fitting accuracy of the J C constitutive equation to the GH4720Li alloy in a large range of strain rates. |
| Issue: | Vol. 44 No. 5 (2023) |
| Published: | 2023-05-28 |
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