Research On Microstructure And Properties Of 90W-7Ni-3Fe Tungsten Heavy Alloy By Rotary Swaging

Due to the continuous upgrading of armor protection technology,the penetration performance of kinetic penetrator was required to be improved again.Tungsten heavy alloys,as the most extensive warhead materials at present,need to meet more stringent environmental requirements.Deformation strengthening was still the most effective way to improve the penetration power of 90W-7Ni-3Fe alloy for armor piercing projectile.In this paper,the high strength tungsten heavy alloy was obtained by the large plastic deformation strengthening technology of rotary swaging.The dynamic mechanical behavior and adiabatic shear sensitivity of 90W-7Ni-3Fe alloy were investigated,and the tensile and compressive strain hardening behavior and strengthening mechanism were analyzed.The Rockwell hardness HRC,mechanical properties and microstructures of 90W-7Ni-3Fe alloy at different rotary swaged parameters?swaged temperature: 850 ?,900 ?,950 ?,and 1000 ?,swaged deformation: 19%,31%,41%,and 56%?were investigated at room temperature.It was found that the strength and HRC of as-sintered 90W-7Ni-3Fe alloy increased significantly and gradually stabilized with increasing rotary swaging deformation,accompanied by a significant decrease in plasticity.The contiguity of W/W particles increased with rotary swaging deformation increasing,accompanied by increasing W particles length-diameter ratio showed fibrosis and the degree of deformation increased significantly.Quasi-static compression(0.001 s^-1,0.01 s^-1,and 0.1 s^-1),dynamic compression(600 s^-1,1300 s^-1,and 2300 s^-1)and impact toughness were deformed to investigate the compression behavior and impact toughness of rotary swaged 90W-7Ni-3Fe alloy at room temperature.Results showed the obvious strain rate sensitivities under the condition of quasi-static compression and dynamic compression at room temperature.The plastic deformation was mainly the coordinated deformation of W particles and the matrix at quasi-static compression,while dynamic compression was a process of plastic deformation of W particles and the matrix simultaneously.Quasi-static compression had significant anisotropy of yield strength.Dynamic compression appeared 20?30 ?m adiabatic shear band at strain rate 2300 s^-1,which can effectively improve the armor penetration performance of rotary swaged 90W-7Ni-3Fe alloy.However,the impact toughness of rotary swaged 90W-7Ni-3Fe alloy was dependent on rotary swaging deformation.The rotary swaged 90W-7Ni-3Fe alloy still maintained good toughness under large deformation,which realized the good coordination of the high strength and toughness of rotary swaged 90W-7Ni-3Fe alloy.In order to explore tensile/compressive stress sensitivity on rotary swaged 90W-7Ni-3Fe alloy,the strain hardening behaviors under tensile/compressive stress were analyzed.Results showed the obvious strain hardening behaviors in rotary swaged 90W-7Ni-3Fe alloy under tensile and compressive tests,and the strain hardening rate gradually decreased with strain increasing.A single linear strain hardening?n=0.04?of rotary swaged 90W-7Ni-3Fe alloy at rotary temperature of 900 ?,and the bilinear strain hardening behavior appeared at 950 ? and 1000 ? under the condition of room-temperature tensile tests.Thermal softening only occurred at large strain at quasi-static compression,while the strain hardening rate quickly became stable with strain increasing at dynamic compression.In contrast,rotary swaged 90W-7Ni-3Fe alloy was more prone to thermal softening under the action of compression stress.The rotary swaged 90W-7Ni-3Fe alloys were treated by heat treatment at the temperature of 1000 ? for 60 min and oil quenching to investigate the evolution of microstructures and mechanical properties.Results showed that the contiguity of W/W particles decreased slightly,and W particles diffused in the matrix after heat treatment.The better comprehensive mechanical properties??_b=1212 MPa,?=13.7%?can be achieved at rotary temperature of 850 ? and the deformation of 56%.In addition,a high strain hardening value and bilinear strain hardening appeared,so the uniform plastic deformation ability was improved.Therefore,the heat treatment can realize the best matching of the strength and plasticity of deformation-strengthened 90W-7Ni-3Fe alloy.