Al-Mg-Mn-Sc-Zr alloys with excellent weldability have emerged as ideal candidates for aerospace applications.Currently,the investigations on the corrosion behavior of alloys under tungsten inert gas(TIG)welding condit...Al-Mg-Mn-Sc-Zr alloys with excellent weldability have emerged as ideal candidates for aerospace applications.Currently,the investigations on the corrosion behavior of alloys under tungsten inert gas(TIG)welding conditions are insufficient.Here,the stress corrosion cracking(SCC)behavior of base metal(BM)and weld zone(WZ)of TIG welded Al-Mg-Mn-Sc-Zr alloys was investigated by using pre-cracked compact tensile samples immersed in 3.5%NaCl solution.The direct current potential drop(DCPD)method was used to record the crack propagation.The microstructure and fracture morphology of different regions of TIG welded joints were studied by SEM,EBSD and TEM,and the SCC crack propagation mechanism of BM and WZ was analyzed.The results demonstrated that the critical stress intensity factor for stress corrosion cracking(K_(ⅠSCC))of BM and WZ was 7.05 MPa·m_(1/2) and 11.79 MPa·m_(1/2),respectively.Then,the crack propagation rate of BM was faster than that of WZ,and BM was more susceptible to SCC than WZ.Additionally,the fracture mode of the BM mainly exhibited transgranular fracture,while the fracture mode of the WZ mainly exhibited intergranular and transgranular mixed fracture.Moreover,SCC crack propagation was attributed to the combined effect of anodic dissolution and hydrogen embrittlement.This study will provide experimental and theoretical basis for the wide application of TIG welded Al-Mg-Mn-Sc-Zr alloys in aerospace.展开更多
The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetrat...The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetration process. In this paper, experiments of WFeNiMo HEA and tungsten heavy alloy (WHA) projectiles penetrating medium-carbon steel were conducted by using the ballistic gun and two-stage light-gas gun that can accelerate projectiles to impact velocities ranging from 1162 m/s to 2130 m/s. Depth of penetration (DOP) at elevated impact velocities of HEA and WHA projectiles were obtained firstly. Combined with the macroscopic and microscopic analysis of the residual projectiles, the transition of the penetration mode of the WFeNiMo HEA projectile was identified systemically. The experimental results indicated that the penetration mode of the HEA projectile changes from self-sharpening to mushrooming with the increase of impact velocity, while for the WHA projectile, the penetration mode is always mushrooming. The microstructure of the residual HEA projectiles showed that the phases tangle with each other and the morphology of the microstructure of the phases differs in the two penetration modes. Besides, the evolution of shear bands and fractures varies in the two modes. The evolution of the microstructure of HEAs causes the sharp-pointed nose to disappear and the HEA projectile ultimately becomes blunt as the impact velocity increases.展开更多
Tungsten heavy alloys have come up as one of the best alternatives for high density fragmenting devices and armor piercing ammunition.Machining is mandatory for obtaining the final shapes of such kind of ammunitions.H...Tungsten heavy alloys have come up as one of the best alternatives for high density fragmenting devices and armor piercing ammunition.Machining is mandatory for obtaining the final shapes of such kind of ammunitions.However,due to high density and elastic stiffness of WHAs,cutting forces will be higher than for most of the metals and alloys;thus,making the machining operation challenging.The machining variable,namely,cutting force components are significantly influenced by the cutting parameters.This paper makes use of Oxley’s predictive analytical model in conjunction with Johnson-Cook constitutive equation to predict forces under different speed and feed combinations during machining of 95 W tungsten heavy alloy.The cutting forces,so predicted by Ml,are considered as input data for the optimization of cutting parameters(cutting speed and feed)using Response Surface Method(RSM).展开更多
基金Project (2023GK1080) supported by the Major Special Projects of Hunan Province of China。
文摘Al-Mg-Mn-Sc-Zr alloys with excellent weldability have emerged as ideal candidates for aerospace applications.Currently,the investigations on the corrosion behavior of alloys under tungsten inert gas(TIG)welding conditions are insufficient.Here,the stress corrosion cracking(SCC)behavior of base metal(BM)and weld zone(WZ)of TIG welded Al-Mg-Mn-Sc-Zr alloys was investigated by using pre-cracked compact tensile samples immersed in 3.5%NaCl solution.The direct current potential drop(DCPD)method was used to record the crack propagation.The microstructure and fracture morphology of different regions of TIG welded joints were studied by SEM,EBSD and TEM,and the SCC crack propagation mechanism of BM and WZ was analyzed.The results demonstrated that the critical stress intensity factor for stress corrosion cracking(K_(ⅠSCC))of BM and WZ was 7.05 MPa·m_(1/2) and 11.79 MPa·m_(1/2),respectively.Then,the crack propagation rate of BM was faster than that of WZ,and BM was more susceptible to SCC than WZ.Additionally,the fracture mode of the BM mainly exhibited transgranular fracture,while the fracture mode of the WZ mainly exhibited intergranular and transgranular mixed fracture.Moreover,SCC crack propagation was attributed to the combined effect of anodic dissolution and hydrogen embrittlement.This study will provide experimental and theoretical basis for the wide application of TIG welded Al-Mg-Mn-Sc-Zr alloys in aerospace.
基金This work is funded by the National Natural Science Foundation of China(No.11790292)the NSAF Joint Fund(No.U1730101).
文摘The appearance of high-entropy alloys (HEAs) makes it possible for a material to possess both high strength and high ductility. It is with great potential to apply HEAs under extreme conditions such as in the penetration process. In this paper, experiments of WFeNiMo HEA and tungsten heavy alloy (WHA) projectiles penetrating medium-carbon steel were conducted by using the ballistic gun and two-stage light-gas gun that can accelerate projectiles to impact velocities ranging from 1162 m/s to 2130 m/s. Depth of penetration (DOP) at elevated impact velocities of HEA and WHA projectiles were obtained firstly. Combined with the macroscopic and microscopic analysis of the residual projectiles, the transition of the penetration mode of the WFeNiMo HEA projectile was identified systemically. The experimental results indicated that the penetration mode of the HEA projectile changes from self-sharpening to mushrooming with the increase of impact velocity, while for the WHA projectile, the penetration mode is always mushrooming. The microstructure of the residual HEA projectiles showed that the phases tangle with each other and the morphology of the microstructure of the phases differs in the two penetration modes. Besides, the evolution of shear bands and fractures varies in the two modes. The evolution of the microstructure of HEAs causes the sharp-pointed nose to disappear and the HEA projectile ultimately becomes blunt as the impact velocity increases.
文摘Tungsten heavy alloys have come up as one of the best alternatives for high density fragmenting devices and armor piercing ammunition.Machining is mandatory for obtaining the final shapes of such kind of ammunitions.However,due to high density and elastic stiffness of WHAs,cutting forces will be higher than for most of the metals and alloys;thus,making the machining operation challenging.The machining variable,namely,cutting force components are significantly influenced by the cutting parameters.This paper makes use of Oxley’s predictive analytical model in conjunction with Johnson-Cook constitutive equation to predict forces under different speed and feed combinations during machining of 95 W tungsten heavy alloy.The cutting forces,so predicted by Ml,are considered as input data for the optimization of cutting parameters(cutting speed and feed)using Response Surface Method(RSM).
