Determination Of Parameters Of Constitutive Model And Research On Aging Treatment Of High Density Nickel-tungsten Alloy

The shell’s material of Anti deep target warhead need high strength,ductility,toughness and excellent capability of dynamic response under high-speed impact.With the increasing demand for projectile penetrating ability,the development of new shell’s material is of practical significance.DT730 high density Ni-W alloys studied in this paper is a kind of Ni₁₇W₃ matrix,containing Co,Ti,exhibiting excellent characteristics of high-density,high ductility and high strength.In view of its application background,this paper carries out the following studies:（1）The mechanical properties of high density Ni-W alloys are obtained by quasi-static compression test at room temperature and 600℃-1000℃and dynamic compression test under different strain rates.Johnson-Cook constitutive model with optimized temperature parameters is determined based on the mechanical properties data above,which is proved to predict the mechanical behavior of high density Ni-W alloys well.σ_eq=665.6876+343.4576ε_eq^0.61081+0.4058 lnε^*_eq1-0.5926T^*0.4073（2）Taylor impact test is carried out to study the response to impact load,deformation and failure mechanism of high density Ni-W alloys.As the impact velocity increase gradually,the Taylor bars show three kinds of failure modes including upsetting,shear failure and crushing.The critical impact velocity is 252m/s,while the contact surface pressure is 5.94GPa.At a low impact velocity,deformation occurs only in the head part.While in the high-speed impact,the rod produces severe plastic deformation,with cracks initiating from the deformed localized area then expanding,resulting in shear failure.As the impact speed continues increasing,unloading waves lead to the generating and growing of cavities,which may interact with cracks then lead to the crushing.（3）In order to obtain the Ni-W alloys with higher strength,variable aging treatment are carried out under different aging temperature（600-800℃）and aging time（2h-12h）,following the composition analysis,morphology analysis and mechanical properties test.The results showed that the grain size of the alloy after aging treatment doesn’t change significantly which remains FCC structure.Aging peak is founded on 750℃-10h,during which alloys exhibit the best mechanical performance.Preliminary analysis shows this is due to the precipitation of high hard phase Ni₄W dispersed...