In this work,the nickel-based powder metallurgy superalloy FGH95 was selected as experimental material,and the experimental parameters in multiple overlap laser shock processing(LSP)treatment were selected based on or...In this work,the nickel-based powder metallurgy superalloy FGH95 was selected as experimental material,and the experimental parameters in multiple overlap laser shock processing(LSP)treatment were selected based on orthogonal experimental design.The experimental data of residual stress and microhardness were measured in the same depth.The residual stress and microhardness laws were investigated and analyzed.Artificial neural network(ANN)with four layers(4-N-(N-1)-2)was applied to predict the residual stress and microhardness of FGH95 subjected to multiple overlap LSP.The experimental data were divided as training-testing sets in pairs.Laser energy,overlap rate,shocked times and depth were set as inputs,while residual stress and microhardness were set as outputs.The prediction performances with different network configuration of developed ANN models were compared and analyzed.The developed ANN model with network configuration of 4-7-6-2 showed the best predict performance.The predicted values showed a good agreement with the experimental values.In addition,the correlation coefficients among all the parameters and the effect of LSP parameters on materials response were studied.It can be concluded that ANN is a useful method to predict residual stress and microhardness of material subjected to LSP when with limited experimental data.展开更多
The application of friction stir welding(FSW) is growing owing to the omission of difficulties in traditional welding processes. In the current investigation, artificial neural network(ANN) technique was employed to p...The application of friction stir welding(FSW) is growing owing to the omission of difficulties in traditional welding processes. In the current investigation, artificial neural network(ANN) technique was employed to predict the microhardness of AA6061 friction stir welded plates. Specimens were welded employing triangular and tapered cylindrical pins. The effects of thread and conical shoulder of each pin profile on the microhardness of welded zone were studied using tow ANNs through the different distances from weld centerline. It is observed that using conical shoulder tools enhances the quality of welded area. Besides, in both pin profiles threaded pins and conical shoulders increase yield strength and ultimate tensile strength. Mean absolute percentage error(MAPE) for train and test data sets did not exceed 5.4% and 7.48%, respectively. Considering the accurate results and acceptable errors in the models' responses, the ANN method can be used to economize material and time.展开更多
AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the...AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the best suitable process among the fusion welding processes such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by evaluating the tensile properties of AA5059 aluminium alloy joints. The fracture path was identified by mapping the low hardness distribution profile (LHDP) across the weld cross section under tensile loading. Optical and scanning electron microscopies were used to characterize the microstructural features of the welded joints at various zones. It is evident from the results that GTAW joints showed superior tensile properties compared to GMAW joints and this is primarily owing to the presence of finer grains in the weld metal zone (WMZ) and narrow heat-affected zone (HAZ). The lower heat input associated with the GTAW process effectively reduced the size of the WMZ and HAZ compared to GMAW process. Lower heat input of GTAW process results in faster cooling rate which hinders the grain growth and reduces the evaporation of magnesium in weld metal compared to GMAW joints. The fracture surface of GTAW joint consists of more dimples than GMAW joints which is an indication that the GTAW joint possess improved ductility than GMAW joint.展开更多
Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens w...Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens were characterized for microstructure and tested for microhardness and wear rate.A hybrid model with a linear function and radial basis function was developed to analyze the influence of nickel,tin,and aging time on the microhardness and tribological behavior of copper-nickel-sin alloy system.The results indicate that increase in the composition of nickel and tin increases the microhardness and decreases the wear rate of the alloy.The increase in the concentration of nickel and tin decreases the peak aging time of the alloy system.展开更多
Laser cladding of powder mixture of TiN and SS304 is carried out on an SS304 substrate with the help of fibre laser.The experiments are performed on SS304,as per the Taguchi orthogonal array(L^(16))by different combin...Laser cladding of powder mixture of TiN and SS304 is carried out on an SS304 substrate with the help of fibre laser.The experiments are performed on SS304,as per the Taguchi orthogonal array(L^(16))by different combinations of controllable parameters(microhardness and clad thickness).The microhardness and clad thickness are recorded at all the experimental runs and studied using Taguchi S/N ratio and the optimum controllable parametric combination is obtained.However,an artificial neural network(ANN)identifies different sets of optimal combinations from Taguchi method but they both got almost the same clad thickness and hardness values.The micro-hardness of cladded layer is found to be6.22 times(HV_(0.5)752)the SS304 hardness(HV_(0.5)121).The presence of nitride ceramics results in a higher micro hardness.The cladded surface is free from cracks and pores.The average clad thickness is found to be around 0.6 mm.展开更多
Surface microstructure and mechanical properties of pearlitic Fe–0.8%C(mass fraction) steel after laser shock processing(LSP) with different laser pulse energies were investigated by scanning electron microscopy(SEM)...Surface microstructure and mechanical properties of pearlitic Fe–0.8%C(mass fraction) steel after laser shock processing(LSP) with different laser pulse energies were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD) and microhardness measurements.After LSP,the cementite lamellae were bent,kinked and broken into particles.Fragmentation and dissolution of the cementite lamellae were enhanced by increasing the laser pulse energy.Due to the dissolution of carbon atoms in the ferritic matrix,the lattice parameter of α-Fe increased.The grain size of the surface ferrite was refined,and the microstructure changed from lamellae to ultrafine micro-duplex structure(ferrite(α)+cementite(θ)) with higher laser pulse energy,accompanied by the residual stress and microhardness increase.展开更多
The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the applicati...The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of load.The experiment was conducted varying the mass concentration of silicon nitride(Si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope(SEM)revealing that the particles of the Zn-Si3 N4 were homogeneously dispersed.The corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing technique.The result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/cm2.The negative shift in the Ecorr revealed the cathodic protective nature of the coating.The microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 Si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3 N4 particles.展开更多
基金Projects(51875558,51471176)supported by the National Natural Science Foundation of ChinaProject(2017YFB1302802)supported by the National Key R&D Program of China。
文摘In this work,the nickel-based powder metallurgy superalloy FGH95 was selected as experimental material,and the experimental parameters in multiple overlap laser shock processing(LSP)treatment were selected based on orthogonal experimental design.The experimental data of residual stress and microhardness were measured in the same depth.The residual stress and microhardness laws were investigated and analyzed.Artificial neural network(ANN)with four layers(4-N-(N-1)-2)was applied to predict the residual stress and microhardness of FGH95 subjected to multiple overlap LSP.The experimental data were divided as training-testing sets in pairs.Laser energy,overlap rate,shocked times and depth were set as inputs,while residual stress and microhardness were set as outputs.The prediction performances with different network configuration of developed ANN models were compared and analyzed.The developed ANN model with network configuration of 4-7-6-2 showed the best predict performance.The predicted values showed a good agreement with the experimental values.In addition,the correlation coefficients among all the parameters and the effect of LSP parameters on materials response were studied.It can be concluded that ANN is a useful method to predict residual stress and microhardness of material subjected to LSP when with limited experimental data.
文摘The application of friction stir welding(FSW) is growing owing to the omission of difficulties in traditional welding processes. In the current investigation, artificial neural network(ANN) technique was employed to predict the microhardness of AA6061 friction stir welded plates. Specimens were welded employing triangular and tapered cylindrical pins. The effects of thread and conical shoulder of each pin profile on the microhardness of welded zone were studied using tow ANNs through the different distances from weld centerline. It is observed that using conical shoulder tools enhances the quality of welded area. Besides, in both pin profiles threaded pins and conical shoulders increase yield strength and ultimate tensile strength. Mean absolute percentage error(MAPE) for train and test data sets did not exceed 5.4% and 7.48%, respectively. Considering the accurate results and acceptable errors in the models' responses, the ANN method can be used to economize material and time.
文摘AA5059 is one of the high strength armor grade aluminium alloy that finds its applications in the military vehicles due to the higher resistance against the armor piercing (AP) threats. This study aimed at finding the best suitable process among the fusion welding processes such as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by evaluating the tensile properties of AA5059 aluminium alloy joints. The fracture path was identified by mapping the low hardness distribution profile (LHDP) across the weld cross section under tensile loading. Optical and scanning electron microscopies were used to characterize the microstructural features of the welded joints at various zones. It is evident from the results that GTAW joints showed superior tensile properties compared to GMAW joints and this is primarily owing to the presence of finer grains in the weld metal zone (WMZ) and narrow heat-affected zone (HAZ). The lower heat input associated with the GTAW process effectively reduced the size of the WMZ and HAZ compared to GMAW process. Lower heat input of GTAW process results in faster cooling rate which hinders the grain growth and reduces the evaporation of magnesium in weld metal compared to GMAW joints. The fracture surface of GTAW joint consists of more dimples than GMAW joints which is an indication that the GTAW joint possess improved ductility than GMAW joint.
文摘Copper alloyed with various compositions of nickel and tin were cast into molds under argon atmosphere.The cast rods were homogenized,solution heat treated,followed by aging for different time duration.The specimens were characterized for microstructure and tested for microhardness and wear rate.A hybrid model with a linear function and radial basis function was developed to analyze the influence of nickel,tin,and aging time on the microhardness and tribological behavior of copper-nickel-sin alloy system.The results indicate that increase in the composition of nickel and tin increases the microhardness and decreases the wear rate of the alloy.The increase in the concentration of nickel and tin decreases the peak aging time of the alloy system.
文摘Laser cladding of powder mixture of TiN and SS304 is carried out on an SS304 substrate with the help of fibre laser.The experiments are performed on SS304,as per the Taguchi orthogonal array(L^(16))by different combinations of controllable parameters(microhardness and clad thickness).The microhardness and clad thickness are recorded at all the experimental runs and studied using Taguchi S/N ratio and the optimum controllable parametric combination is obtained.However,an artificial neural network(ANN)identifies different sets of optimal combinations from Taguchi method but they both got almost the same clad thickness and hardness values.The micro-hardness of cladded layer is found to be6.22 times(HV_(0.5)752)the SS304 hardness(HV_(0.5)121).The presence of nitride ceramics results in a higher micro hardness.The cladded surface is free from cracks and pores.The average clad thickness is found to be around 0.6 mm.
基金Projects(50801021,51201061)supported by the National Natural Science Foundation of ChinaProject(144200510009)supported by the Henan Province Program for Science and Technology Innovation Excellent Talents,China+1 种基金Project(152102210077)supported by the Science and Technology Project of Henan Province,ChinaProject(2015XTD006)supported by the Science and Technology Innovation Team of Henan University of Science and Technology,China
文摘Surface microstructure and mechanical properties of pearlitic Fe–0.8%C(mass fraction) steel after laser shock processing(LSP) with different laser pulse energies were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray diffraction(XRD) and microhardness measurements.After LSP,the cementite lamellae were bent,kinked and broken into particles.Fragmentation and dissolution of the cementite lamellae were enhanced by increasing the laser pulse energy.Due to the dissolution of carbon atoms in the ferritic matrix,the lattice parameter of α-Fe increased.The grain size of the surface ferrite was refined,and the microstructure changed from lamellae to ultrafine micro-duplex structure(ferrite(α)+cementite(θ)) with higher laser pulse energy,accompanied by the residual stress and microhardness increase.
文摘The effect of Zn-Si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of load.The experiment was conducted varying the mass concentration of silicon nitride(Si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon Optical Microscope and Scanning Electron Microscope(SEM)revealing that the particles of the Zn-Si3 N4 were homogeneously dispersed.The corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing technique.The result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/cm2.The negative shift in the Ecorr revealed the cathodic protective nature of the coating.The microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 Si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated Si3 N4 particles.
