Abstract:Two single track multi-layer walls with linear energy inputs (LEIs) of 219 and 590 J/mm were deposited by cold metal transfer-based wire arc additive manufacturing system. Combined with the X-ray diffraction technique, scanning electron microscope and uniaxial tensile tests, the influences of LEI and cooling rate (CR) on the microstructure evolution, mechanical properties and fracture mechanisms of the studied steel are analyzed. It is observed that the microstructures of the studied steel are mainly composed … Show more
“…It is because that the reduction of deformation time at a high strain rate limits the growth of DRX grains. [ 49 , 50 ]. The elongated grain boundaries can confirm the absence of DRX behavior when the strain rate is relatively high ( Figure 3 ).…”
The hot deformation characteristics of a GH4169 superalloy are investigated at the temperature and strain rate ranges of 1193–1313 K and 0.01–1 s−1, respectively, through Gleeble-3500 simulator. The hot deformed microstructures are analyzed by optical microscopy (OM), transmission electron microscopy (TEM), and electron backscattered diffraction (EBSD) technology. The effects of deformation parameters on the features of flow curves and annealing twins are discussed in detail. It is found that the shapes of flow curves are greatly affected by the deformation temperature. Broad peaks appear at low deformation temperatures or high strain rates. In addition, the evolution of annealing twins is significantly sensitive to the deformation degree, temperature, and strain rate. The fraction of annealing twins first decreases and then rises with the added deformation degree. This is because the initial annealing twin characters disappear at the relatively small strains, while the annealing twins rapidly generate with the growth of dynamic recrystallized grains during the subsequent hot deformation. The fraction of annealing twins is relatively high when the deformation temperature is high or the strain rate is low. In addition, the important role of annealing twins on dynamic recrystallization (DRX) behaviors are elucidated. The obvious bulging at initial twin boundaries, and the coherency of annealing twin boundaries with dynamic recrystallized grain boundaries, indicates that annealing twins can motivate the DRX nucleation during the hot deformation.
“…It is because that the reduction of deformation time at a high strain rate limits the growth of DRX grains. [ 49 , 50 ]. The elongated grain boundaries can confirm the absence of DRX behavior when the strain rate is relatively high ( Figure 3 ).…”
The hot deformation characteristics of a GH4169 superalloy are investigated at the temperature and strain rate ranges of 1193–1313 K and 0.01–1 s−1, respectively, through Gleeble-3500 simulator. The hot deformed microstructures are analyzed by optical microscopy (OM), transmission electron microscopy (TEM), and electron backscattered diffraction (EBSD) technology. The effects of deformation parameters on the features of flow curves and annealing twins are discussed in detail. It is found that the shapes of flow curves are greatly affected by the deformation temperature. Broad peaks appear at low deformation temperatures or high strain rates. In addition, the evolution of annealing twins is significantly sensitive to the deformation degree, temperature, and strain rate. The fraction of annealing twins first decreases and then rises with the added deformation degree. This is because the initial annealing twin characters disappear at the relatively small strains, while the annealing twins rapidly generate with the growth of dynamic recrystallized grains during the subsequent hot deformation. The fraction of annealing twins is relatively high when the deformation temperature is high or the strain rate is low. In addition, the important role of annealing twins on dynamic recrystallization (DRX) behaviors are elucidated. The obvious bulging at initial twin boundaries, and the coherency of annealing twin boundaries with dynamic recrystallized grain boundaries, indicates that annealing twins can motivate the DRX nucleation during the hot deformation.
“…A few previous studies backed up the claims made. According to [20], the correct current choice provides a better deposition rate and penetration on the weld material. The high deposition rate and good penetration enhance the material's strength.…”
This research focuses on the capabilities of coldArc GMAW in the behavior of heat input to the weld bead dimension. In this study, the effect of process GMAW of 308L stainless steel filler wire with a thickness of 1.2 mm and 304L stainless steel base plate, with a dimension of 120 mm x 25 mm x 10 mm (height x width x thickness) by applying WAAM. The data was collected using MATLAB of a Smart Weld Rosenthal’s Steady-State 3D Isotherms. A Taguchi response was used in the DOE method with Minitab software to analyze the effect of process parameters on height, width, and depth of weld bead dimension during GMAW. The experiments were conducted following the low, mid, and high input parameters will show the different structures of weld bead dimension, which include 70 A, 75 A, and 78 A (arc current), 15 V, 16 V, and 17 V (voltage), 400 mm/min, 600 mm/min, and 800 mm/min (welding speed). Hence, the optimum value is 75 A, 16 V, and 800 mm/min, and the most significant parameters to deposit stainless steel with coldArc GMAW were welding speed followed by arc current and voltage.
“…Additive manufacturing processes enable considerable acceleration of the process planning and reduction of the costs for the manufacture of finished products [1]. In particular, additive manufacturing (AM) processes are widely applied in the manufacture or repair of complex metallic products by means of local restoration by a metallic wire or powder [2][3][4]. Depending on the heat source, AM processes are divided into wire arc additive manufacturing (WAAM), laser powder bed fusion (LPBF) and electron-beam melting [3,4].…”
Section: Introductionmentioning
confidence: 99%
“…Many studies in the area of additive manufacturing are focused on a different series of steels, considering the fact that almost 80% (weight percent) of all metallic parts for engineering applications are made of steel [1][2][3][4]13]. Most often used in AM are austenitic steels.…”
This paper investigates the effect of cold working via layer-by-layer peening on the microstructure and properties of a 308LSi steel workpiece produced by the wire deposition welding with a consumable electrode following the principle of 3D printing. The microstructure, phase composition and mechanical properties of the metal are studied before and after the workpiece synthesis. In the microstructure of the workpieces produced by peening, there is, in addition to austenite, a small quantity of fine-dispersed carbides and residual δ-ferrite in the interdendritic spaces. It is demonstrated that the use of layer-by-layer cold working in the process of deposition welding enables eliminating transcrystallization of the deposited metal, promotes an increase in the microstructure’s degree of dispersion and a more uniform distribution of fine-dispersed carbides in the volume of the dendrites. It is found that these structural features of the deposited metal in the additive manufacturing of a workpiece with layer-by-layer peening lead to an enhancement of the strength characteristics as compared to the material produced by the conventional wire deposition welding. Meanwhile, the level of the ductility characteristics remains high.
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