Journal of Manufacturing Processes最新文献

The widespread application of Inconel 738LC in laser additive manufacturing is limited due to its poor formability, inferior weldability, and heightened crack susceptibility resulting from its high titanium + aluminum content. In this study, we propose adding micro-sized TiC particles into Inconel 738LC to improve its printability and cracking resistance. Inconel 738LC and Inconel 738LC-1 wt% TiC samples were fabricated by laser powder bed fusion with varying processing parameters. The microstructural characteristics, crack characterization, crack suppression mechanisms, and microhardness properties were comprehensively investigated. Results reveal that solidification cracking and liquation cracking predominate in Inconel 738LC samples. Severe micro-segregation at grain boundaries and continuous oxide-rich liquid films contribute to grain boundary embrittlement and promote cracking. The addition of TiC particles markedly reduces defects such as lack of fusion and cracks. Added TiC particles play a crucial role in refining microstructures and facilitating the precipitation of nano-sized MC carbide particles. A more equiaxed grain shape with tortuous grain boundaries is conducive to impeding crack propagation. Reduced local strain concentration and diminished micro-segregation also contribute to crack suppression. The principal mechanisms for microhardness enhancement in Inconel 738LC-TiC samples encompass densification behavior, grain boundary strengthening, and Orowan strengthening.

This study employed Friction Stir Extrusion (FSE) on the LM13 aluminum alloy to fabricate tubes using three distinct tool head designs: cylindrical, 30° taper, and 60° taper profiles. A comprehensive analysis of the microstructures and mechanical properties of the resulting samples was performed. A numerical study was conducted to model the process dynamics, focusing on temperature and strain distributions, material flow patterns, and the evolution of force, torque, strain, and strain rate. Findings indicated that the axial force with the cylindrical tool was 4–5 times greater than with tapered tools, while forces for the 30° and 60° taper tools were comparable. The 30° taper tool generated the highest strain value of 280 mm/mm, which significantly enhanced the mechanical strength of the pipe up to 139 MPa while it was 85 MPa in the base metal. However, the cylindrical tool had a much higher average strain rate of around 40 1/s, compared to below 10 1/s for the tapered tools, yet it was less effective at reducing porosity and breaking Si particles due to insufficient strain. Additionally, material flow patterns differed: with the cylindrical tool, flow moved from the periphery to the center, while tapered tools directed flow from the center toward the pipe wall.

Springback is an inevitable phenomenon in plate forming. Compared with single-curved plates, the springback prediction of double-curved plates is more difficult due to the mutual influence of bidirectional curvature. This work proposes a new springback calculation method for double-curved medium thick plates based on the curvature of discrete points. Considering the transverse load and friction, the new method discretizes the double-curved plates into strips and calculates the plastic bending moments at discrete points of a single strip under different axial forces. Then it obtains the springback ratios at discrete points by considering the bidirectional coupling effect between strips. A series of sail-shaped and saddle-shaped medium thick plates with different curvature radii and thicknesses are finite element (FE) numerically simulated. Experiments are also carried out to validate the new method. By comparing the theoretical, numerical, and experimental results, it can be concluded that the calculation method proposed in this work can predict the springback quickly and provide rapid guidance for practical stamping. In this work, springback ratio and springback displacement are used to characterize the springback, which both show the springback of sail-shaped plates with the same curvature radius and thickness is greater than that of saddle-shaped plates. The varying curvature radius affects springback similarly in sail-shaped and saddle-shaped plates, but varying thickness does not.

In the quest for seeking aluminum alloys with high printability, AlSi10Mg alloy has been sought as one of the most promising candidates for the laser powder bed fusion (LPBF) technique. Despite the extensive research conducted in LPBF AlSi10Mg, the development of printing parameters to obtain a combination of low porosity and roughness, as well as the desired combination of strength, elongation, and fatigue properties, is considered as one of the most significant difficulties to meet the minimum requirements specified in the standards. Due to the high surface roughness observed in the printed samples using standard printing parameters, this research aims to obtain a combination of low roughness and porosity, as well as excellent tensile and fatigue properties through the development of printing parameters including layer thickness, laser power, scan speed, and hatch distance. Among the developed parameters, decreasing the layer thickness from 60 μm to 50 μm considerably mitigated the surface roughness with the laser power (360 W), scan speed (1550 mm/s), and hatch distance (150 μm). In addition, the optimal stress relief heat treatment at 285 °C for 240 mins was determined for the proposed 50 μm layer thickness to meet the tensile test requirements.

Haynes 230 is widely used in high-temperature regions in the aerospace field. However, the long-term exposure to high-temperature environments results in catastrophic structural failures. Therefore, how to make the heat evacuate quickly and efficiently has become an urgent problem to be solved. Here, we have investigated for the first time the use of Cu-Mo30Cu-Ti composite foil as a thermal interface material to join the C_f/C composite and Haynes 230 in the form of brazing to attain stable operation of the component. The results show that the Cu-Mo30Cu-Ti composite foils form a metallurgical joining with the matrix materials and construct a heat transfer channel between them. When the brazing parameter reaches 1220 °C for 10 min, the thermal conductivity (29.9–34.8 W·m⁻¹·K⁻¹, testing in the range of 600–900 °C) of the joint is improved by 500 % ~ 600 % compared with that before brazing (4.5–5.5 W·m⁻¹·K⁻¹). Our work provides some references to promote the application of C_f/C composite and Haynes 230 in future high-temperature thermal management.

Aiming at the lack of theoretical calculation formulas for inner and outer spinning force in the asymmetric counter-roller spinning process, and the difficulty of direct measurement or conversion of indirect measurement of spinning force under the active rotation condition of rollers, as well as the time-consuming simulation analysis, a theoretical calculation method for asymmetric active counter-roller spinning (AACRS) force by combining strain electrical measurement and simulation is proposed. The initial theoretical calculation model of the inner and outer spinning force for the AACRS process is established based on the energy method. Then, the method of combining the indirect electrical measurement with dynamic simulation analysis (IEM&DS method) is proposed, and the equivalent section coefficient S_WE is used as the pivot to obtain the actual spinning force value equivalently. On this basis, the dynamic and static strain analysis test platform is built, and the modified theoretical calculation formula of spinning force under the counter-roller spinning process is obtained based on the dynamic strain test results. The results show that the theoretical calculation method can directly calculate the inner and outer spinning force values more accurately. The relative error between the corrected outer spinning force and the equivalent measured value is only 6.38 %, improving the accuracy by 49.65 % and 3.46 % compared with the uncorrected theoretical calculation and simulation values, respectively. This method effectively enhances the accuracy of spinning force acquisition while reducing the simulation time and experimental costs.

This study first proposes a novel model that mathematically maps the geometric errors of machine tools to freeform surface contour errors. Specifically, leveraging a kinematics-based geometric error model, the actual tool path for machining a freeform surface can be obtained, which deviates from the tool position surface (TPS) based on Non-Uniform B-Spline (NUBS) surface interpolation. The shortest distance from the center point of the tool nose arc to the tool position surface is then used to derive the contour error distribution of the TPS. Then, using this model, the sensitivity of freeform surface contour errors to geometric errors, for different freeform surfaces and machine tool configuration parameters, is calculated through global sensitivity analysis. The results reveal that as the surface slope increases, the number of sensitive geometric error terms rises. Additionally, the more pronounced the non-rotating characteristics of the surface, the higher the sensitivity of ${\theta }_{\mathrm{zc}}$. Moreover, the tool's position on the rotating B-axis influences the B-axis positioning error ${\theta }_{\mathrm{yb}}$. Finally, the compensation experiments based on sensitivity analyses show that the proposed method can significantly decrease the contour error of freeform surfaces by approximately 30.85 %, demonstrating its feasibility and effectiveness in compensating for the sensitive geometric errors identified by the proposed model.