Issue 07, 2026
Void evolution model-based forging process planning for compacting large steel ingots
WANG Zong-yang;FENG Chao;AI Hai-kun;YANG Hang;CUI Zhen-shan;To enhance the predictability in the process planning for compacting large steel ingots, a compaction prediction method integrating void evolution model was developed through the secondary development technology of DEFORM-3D finite element software. The procedure was applied to simulate the evolution of void morphology and the compaction process response throughout the entire process from upsetting to radial compression of large steel ingots. Simulation analyses under various initial height-diameter ratios(H0/D0=1.0-2.0)and initial void aspect ratios(λ0=1-8) of steel ingots were carried out, which revealed the evolution laws of variables including void aspect fraction and relative volume fraction with process parameters.A void compacting process planning procedure based on “parameter calculation, constraint evaluation, and iterative optimization” was established. The results indicate that during radial compression, the initial void aspect ratio significantly affects the critical reduction rate for void closure. When λ0=8, the critical reduction rate is as low as 19.6%, whereas when λ0=1, the critical reduction rate reaches 28.4%. The proposed forging process planning procedure successfully characterizes the void compacting behavior in large steel ingots, with a prediction deviation within 7%, so that it establishes a robust, efficient, and precise method for void compacting process planning.
Cladding hot extrusion process of a novel nickel-based powder superalloy
MA Xiang-dong;PENG Wei-jin;XIAO Lei;GUO Jian-zheng;FENG Gan-jiang;To address the issues of narrow hot extrusion process parameter windows, difficulty in controlling uniform fine-grained microstructure, and low effective material utilization rate of alloy materials for nickel-based powder superalloy, a combined approach of finite element numerical simulation and experimental validation was employed to systematically investigate the influence of different structural forms of cladding on hot-extruded bars during the cladding hot extrusion process of a new nickel-based powder superalloy FGH4113A(WZ-A3). The results show that the finite element numerical simulation results of the FGH4113A alloy hot extrusion process are in good agreement with the experimental results for both assembled cladding structure form and integrated cladding structure form. The macroscopic morphology entire hot extruded bar is rather straight. The microstructure is fine and uniform, and sufficient dynamic recrystallization has occurred. The average grain size is above ASTM 11.0. The effective material utilization rate of the FGH4113A alloy hot extruded bar has been significantly improved from 55.4% of the traditional assembled extrusion cladding structure form to 81.4% of the optimized integrated extrusion cladding structure form, effectively reducing the production cost.
Springback and cross-sectional distortion law in TA16 computer numerical control rotary draw bending forming
DAI Yi-cong;WANG Hui;YANG Qiu-cheng;YUAN Jun-tao;To reveal the forming mechanism of TA16 titanium tube in CNC rotary draw bending forming, and to achieve precise forming and springback control, an elasto-plastic finite element model of the entire CNC rotary draw bending process for TA16 titanium tube was established based on the ABAQUS/Explicit finite element platform. The effects of mandrel extension and relative bending radius on tube springback and cross-sectional distortion were systematically investigated, and the reliability of the model was verified through experiments. The results show that as the relative bending radius decreases, the cross-sectional distortion rate and wall thickness reduction rate of the tube increase significantly. When R/D<3, the cross-sectional distortion rate exceeds the engineering allowable limit of 9%. The mandrel extension has a nonlinear impact on forming quality. Within the studied range, the cross-sectional distortion rate decreases monotonically from 11.28% to 9.82%, while the outer wall thickness reduction rate increases from 12.87% to 14.77%, with a smaller change in the inner wall thickness increase rate. The increase of mandrel extension reduces both the springback angle and springback radius, with a more significant reduction in the springback radius. A linear relationship model between the springback angle and bending angle is established, providing theoretical guidance and process reference for springback compensation in the actual production of TA16 titanium tube.
Mechanism analysis and deformation prediction of springback in chain-die forming of ultra-high-strength steel hat-shaped part
LIU Min;GAO Chang;YU Hai-dong;The springback mechanism is complex and the forming geometric accuracy is insufficient in chain-die forming of ultra-high-strength steel hat-shaped part. Aiming at the problem, a springback analysis method based on composite mechanism decoupling and collaborative prediction was proposed. The springback behavior caused by the strong Bauschinger effect and path dependency of ultra-high-strength steel is decoupled into two mechanisms including concurrent springback and sequential springback, with dynamic coupling achieved using an exponential decay weighting function. For concurrent springback, a recurrent neural network model constructed from mesh point clouds was constructed to compute multi-die springback with global coupling characteristics. For sequential springback, the segmented equivalent beam theory is applied to decompose deformation along the longitudinal axis, enabling the calculation of die-by-die springback with local cumulative effects for each die. By adopting exponential decay weighted function to couple the prediction results of two mechanisms, collaborative prediction of the overall springback behavior was realized. A finite element model for MS1500 ultra-high-strength steel hat-shaped part chain-die forming was established to verify the accuracy of the proposed model. The results show that the predicted values in the sidewall and the web regions agree closely with the simulation values, by which the local accumulation-global coupling mechanism of springback in chain-die forming can be revealed.
Nosing forming quality of ring with weld and its improvement methods
OUYANG Ya-wen;ZHAO Yi-xi;LI Xiao-kai;HU Lan;To meet the requirements for the integral forming of a large-scale dome component, the integral forming method of “rolled-welded blank preparation + nosing forming” was proposed. Taking the 2219-T351 aluminum alloy ring with weld as the research object, the influences of weld strength coefficient and weld number on the nosing forming quality of the ring with weld were analyzed through finite element simulation. The effects of different local thickening methods on the nosing forming quality of the ring with weld were compared. The results show that when the weld strength coefficient is below 0.9, the ring with weld exhibits significant instability and wrinkling phenomenon. When it is above 0.9, the forming results are essentially the same as those of the ring without weld. As the weld strength coefficient increases from 0.5 to 0.9, the wrinkling degree of the ring with weld decreases linearly from 9.1% to 0.2%. As the weld number increases, the wrinkling degree of the ring with weld slightly decreases, but this does not significantly improve the wrinkling phenomenon of the ring. Compared with stage-type and linear-type local thickening methods, the arc-type local thickening method effectively improves the nosing forming quality of the ring with weld. But the arc-type local thickening thickness must be less than 5 mm. Furthermore, the arc-type local thickening method can also reduce the requirements for the weld strength coefficient of the ring with weld.
Gas pressure loading path and forming defects of superplastic forming/diffusion bonding of TA15 titanium alloy four-layer hollow parts
LIU Tai-ying;CHEN Kun-qi;DONG Jian-jian;LIU Wen-jun;CHEN Ming-he;ZHU Dong-mei;WU Yong;In order to explore the influence law of different gas pressure loading paths on the forming quality of TA15 titanium alloy four-layer hollow parts prepared by superplastic forming/diffusion bonding, MSC.Marc simulation software was used to carry out numerical simulation analysis, and a reasonable gas pressure loading path was optimized, and four-layer hollow parts were successfully fabricated.Through the MSC.Marc superplastic forming module, the ideal gas pressure loading curve with an equal strain rate of 0.001 s-1 at a bulging pressure of 2.0 MPa at 930 ℃ was solved, and the multi-order curve fitting consistent with actual working conditions was carried out. The rationality of the process was judged by the thickness change of the parts in the finite element simulation results, the degree of fit, and whether the forming defects are generated, and then the process interval of the component was determined. The results show that when the gas pressure loading is too fast, there will be defects such as local fracture and pore tearing. When the gas pressure loading is too slow, the welding rate is low and the cavity is proliferated. Although prolonging the shaping time can improve the welding rate and inhibit the growth of the cavity, it will cause defects such as surface oxidation and internal rib bending. The obtained TA15 titanium alloy four-layer hollow parts have good forming quality and no defects, such as grooves when the gas pressure loading is reasonable. The wall thickness distribution of the four-layer hollow parts was measured by an ultrasonic thickness measuring instrument and found to be uniform. The average thickness of the key parts is 1.52 mm, and the minimum thickness is 1.31 mm at the round corner of the cell body. The minimum wall thickness of the core plate is 0.39 mm, and the thinning rate is 61 %. The minimum wall thickness of the panel is 0.92 mm, and the thinning rate is 8%. The test results are basically consistent with the finite element analysis results.
Effect of wire-filled friction stir welding process on forming quality of Al-Li alloy T-joints
QIU Yu;GUAN Wei;ZENG Yuan-song;DONG Ji-hong;ZHAO Hua-xia;WANG Bing-yang;AVIC Manufacturing Technology Institute;2A97-T3 Al-Li alloy sheets with thickness of 2.8 mm were selected as the test materials. Filler wire welding on the inner corner of T-joints was realized via wire-filled stir welding process, and sound defect-free T-joints with satisfactory forming quality were obtained. Combined with visual inspection, ultrasonic testing, industrial CT testing and cross-sectional metallography, the effects of filler wire profile, assembly gap and process parameters on the welding forming quality of T-joints were investigated. The results show that compared with circle filler wires, square filler wires deliver superior weld forming quality. Defects initiate in T-joints when the gap between skin and stringer plate reaches approximately 1.09 mm. Defect size rises with increasing gap value, defect morphology evolves from tiny voids to massive insufficient filling, and defect locations extend gradually along the height direction of the stringer. Sound defect-free T-joints with satisfactory forming quality can be produced using square filler wires under the rotational speed of 2000 r·min-1and the welding speed ranging from 50 to 100 mm·min-1.
Numerical simulation of FSW-T welding temperature field of AA7055/AA2195 alloy plate based on CEL method
ZUO Du-quan;ZHANG Yuan-xiu;HAN Yan-jie;XU Tian-yu;YE Ti;GAO Chong;Based on the coupled Eulerian-Lagrangion(CEL) method, a finite element simulation model of friction stir welding for T-joints of dissimilar alloy plates of AA7055 alloy and AA2195 alloy was innovatively established, and the dynamic temperature field during the entire welding process was simulated and analyzed. The results show that under the process combination parameters of w=400 r·min-1, v=60 mm·min-1, and h=0.21 mm, the high-temperature area is concentrated around the shaft shoulder, and the temperature on the advancing side is higher than that on the receding side by approximately 14.6 ℃. The temperature fields of the characteristic points in the central area of the weld and the different paths in the gradient direction of the thin plate all show an asymmetric M-shaped bimodal distribution. The characteristic points far from the weld area are symmetrically distributed in an inverted V shape. The temperature of the workpiece along different paths(Z1, Z2, Z3) in the Y direction of the cross-section shows a nonlinear attenuation towards the base metal area, and the temperature in the weld core area is the highest, with the temperature gradient in the heat-affected zone being the most significant, which conforms to the thermally mechanical coupling mechanism.
Effects of heat treatment state and milling process parameters on distribution and evolution mechanism of residual stress in milled titanium alloy forgings
TU Bin-lin;LIU Shuo;XIONG Wei;WU Hui-ping;CHEN Jun;To elucidate the distribution patterns of residual stress under different experimental conditions in the microscopic evolution, residual stresses at different positions were measured and microstructures of tested specimens were characterized based on the rough machining and finish machining milling experiments for the edge-wrapped simplified forging billet of TC4 titanium alloy before and after annealing. The effects of initial residual stress and milling parameters on the milling residual stress were investigated. The results indicate that residual stress in the feed direction on the outer surface of unannealed forgings after rough milling is 1.5 times greater than that in annealed forgings, initial residual stress plays a dominant role in alleviating tensile effects during rough milling.The initial residual stress inside the forging dominates during rough milling, while it exerts a minor effect on finish milling. However, the cumulative effect of milling passes becomes predominant in finishing, leading to higher residual stress. The density of geometrically necessary dislocations(GNDs) after finish maching is increased by 48.7% compared to rough maching, indicating a stronger plastic strain gradient.
Research on stable interval of direct ink writing of 316L stainless steel particles
HUANG Ming-qiang;GUO Jun-qing;XIANG Nan;CHEN Fu-xiao;ZHANG Xin-min;Using 316L stainless steel metal particles as raw materials, the influence of process parameters such as printing speed, extrusion pressure and nozzle height on the direct ink writing quality of metal particles was investigated. The influence laws of each parameter on the filament width and printing stability were obtained. The results show that under the parameter combination of nozzle diameter of Φ0.5 mm, extrusion pressure of 0.4 MPa, nozzle height of 1.5 mm, and printing speed of 35 mm·s-1, metal particle products with high precision can be printed. A theoretical model of the cross-sectional morphology of 316L stainless steel metal particle direct ink writing filaments was proposed. It is found that the normalized height h′ with in the range of(3.5, 5) and the normalized speed V′ with in the range of(1.566, 2.312) are both positively linearly correlated with the filament size, and the stable forming range of metal particle direct ink writing is determined.