Journal of Materials Processing Technology最新文献

The drilling and cutting of carbon fiber-reinforced epoxy resin matrix composite (CFRP) structural parts is a prerequisite for one-off moulding and assembly connections. However, the thermal ablation effect observed during nanosecond laser hole-making of CFRP results in significant accuracy errors and thermal damage defects in the quality of the holes obtained from the process. To enhance the quality of laser-drilling CFRP holes, a spiral drilling path was employed in this work. The influence of diverse drilling methodologies, encompassing the trajectory of the laser beam, the spacing between scans, and the direction of the suction system's pumping, on the quality of the holes was examined. The impact of these techniques on the precision and integrity of the holes was assessed in terms of their dimensions, the quality factor, the width of the heat-affected zone (HAZ), and the prevalence of microscopic defects. The results demonstrated that when the drilling strategy involves moving the laser beam from the outside to the inside (Scheme I), a scanning spacing of 20 μm, and backward pumping, the optimal micro-hole accuracy and surface morphology, as well as minimal thermal damage defects can be achieved. This study provides a reference for further optimization of the nanosecond laser drilling process.

Tungsten-copper (W-Cu) joints hold immense promise as plasma-facing materials in fusion reactors. However, the inherent immiscibility of W-Cu poses significant challenges in joint fabrication. Here, we introduce an innovative methodology that incorporates laser texture, W surface nano-activation, and subsequent diffusion bonding to fabricate W-Cu joints. Remarkably, the joints achieved exhibit unparalleled mechanical properties, with a peak tensile strength of 201 MPa and a shear strength of 141 MPa, surpassing previously reported W-Cu joints. To gain insights into the underlying mechanisms, we conducted a multiscale analysis utilizing scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and density-functional theory (DFT) calculations. Our findings reveal a unique embedded structure and a metallurgically bonded interface at the W-Cu junction. Furthermore, the diffusion zone at the interface exhibits a fascinating hybrid crystal structure, maintaining a body-centered cubic (BCC) structure in certain regions while displaying a tetragonal crystal structure (with lattice parameters a=b=2.8617, c=3.44) in others. This tetragonal crystal structure formation within the W-Cu diffusion zone remains unexplored in previous literature. In summary, this novel W-Cu bonding approach not only offers a cutting-edge solution for modern manufacturing and fusion energy applications but also lays a solid theoretical foundation for understanding the intricate microstructure-property relationships in W-Cu systems.

Fused silica is an excellent window material widely used in ultraviolet transmission optical system. Crack-free ductile dry grinding is a novel method for the efficient fabrication of fused silica. The grinding temperature field has an important influence on the grinding process. However, most previous studies assumed that the grinding temperature was independent of the wheel’s wear. In this paper, a temperature field model of the ductile dry grinding of fused silica is developed based on wheel wear topographies. Simulated wheel topographies with the same statistical parameters as the realistic wheel wear topographies are reconstructed based on the convolution filtering and Johnson transformation algorithm. The theoretical temperature field is the superposition of the thermal effects induced by effective cutting grain point heat sources extracted from the simulated wheel topographies. The theoretical prediction accuracy of the wheel-workpiece contact zone is validated by an infrared radiation transmission method. This model not only provides opportunity to explore the material removal mechanisms and improve the surface generation quality of fused silica during the wear process of the wheel, but also could be extended to provide the basis for the utilization of grinding heat or prevention of grinding thermal damage for other isotropic materials.

Aluminum alloy 5052 is used extensively in various industries, including aerospace, shipbuilding, and automotive manufacturing. Components made from this alloy often require welding treatments; however, in marine environments, these welds are susceptible to corrosion, which affects their durability and service life. In this study, power-ball combined ultrasonic shot peening (USSP) was used for surface-strengthening 5052 aluminum alloy welds. The resulting surface characteristics and corrosion resistance were examined, and the compared to the untreated sample, the USSP-treated sample showed a shift in the stress state from residual tensile stress (31.4 MPa) to residual compressive stress (−257.5 MPa). Immersion and electrochemical corrosion experiments confirmed that the formation of residual compressive stress and a gradient structure on the surface enhanced the corrosion resistance, which was substantiated by detailed characterization. The corrosion rate of the treated aluminum alloy weld sample (7.18 μm/year) decreased by 72.90 % compared with that of the untreated sample. The study findings indicate that the powder ball combined USSP is a potential method for improving the corrosion resistance of aluminum alloy welds in marine environments.

Excellent strength and favorable formability are two important mechanical properties of stainless steel, but there is usually a trade-off between both properties. However, it has been suggested in recent studies that preparing microstructures with a non-homogeneous structure can effectively achieve strength-ductility synergy. Given these facts, a microstructure with bimodal grain structures was prepared in this study by short-time electric pulse treatment (EPT). Besides, the evolution of microstructures and mechanical properties of Cu-bearing stainless steel during EPT was analyzed. The results demonstrated that the non-uniform heating in the EPT process can rapidly promote localized grain growth, thus forming a bimodal grain structure compared with conventional heat treatment. The microstructure of the fine grains formed random textures, while the coarsened grains showed stronger textures. After EPT, the amount of S {123} < 634 < 634 >-type textures increased significantly, with the proportion reaching up to 30.1 %. There was also a certain amount of brass {110} < 112 >- and copper {112} < 111 >-type textures. Compared with the solution-treated samples, the best overall mechanical properties were detected under the optimal electric pulse parameters, which ultimately realized a synergistic increase of 11.8 % and 10.2 % in the ultimate tensile strength and ductility. The excellent strength-ductility synergy was closely related to heterogeneous deformation-induced (HDI) strengthening and textures induced by the bimodal grain structure. This finding may provide novel insights for enhancing the formability of biomedical metallic materials.

Compacted Graphite Iron (CGI) represents a unique combination of the characteristics of grey and spheroidal cast irons, sparking significant interest over the past two decades, particularly as a favoured material in several automotive industry applications, including engine components and heavy-duty vehicle parts. Despite its growing prominence, the full potential of CGI remains underutilised, primarily due to its lower productivity rate compared to grey cast iron. This paper comprehensively reviews existing research on CGI machining, emphasising the challenges and exploring opportunities for development in this field. A detailed comparison between the machining of compacted graphite iron, grey cast iron and spheroidal graphite cast iron is provided, highlighting the unique characteristics associated with CGI. The influence of microstructure and chemical composition on machining processes is thoroughly examined and deliberated. Moreover, this review delves into the effects of various process variables on CGI machining, including cutting tools, lubrication, and cooling methods. The paper concludes by discussing potential future trends and innovations in CGI machining, offering a prospective outlook on how these developments could bridge the productivity and literature gap and enhance the utilisation of CGI in industrial applications.

In present work, three press-hardened steel (PHS) sheets were designed for three typical manufacturing processes: cold-rolling (CR) process with about 1.5 km, thin slab continuous casting and rolling (TSCR) process with about 300 m, and Castrip process with about 50 m. Despite the similar constituents of mixed ferrite and pearlite, there were different microstructure characteristics and chemical distributions of these three PHS sheets. The press-hardened steel by Castrip process contained ultrafine pearlite lamella of about 198 nm, accompanying with high-density dislocations (∼10¹⁴ /m²). It was coarse pearlite lamella of 503 nm for press-hardened steel by TSCR process, while it was spheroidized pearlite with the average cementite particle size of 464 nm for press-hardened steel by CR process. The dislocation densities were ∼10¹³ and ∼10¹² /m² for press-hardened steels by TSCR and CR process, respectively. Subsequently, three press-hardened steel sheets were reheated to simulate the hot stamping process. From thermodynamics, press-hardened steel sheet by Castrip process could induce the earliest reversed austenite transformation due to more C and Mn. Kinetically, the high-density dislocations and ultrafine-lamella pearlite together created the fastest rate for reversed austenite transformation. Meanwhile, the mechanical properties of Castrip sheet could firstly reach 1500 MPa grade under the short-time heating condition (below 2 min). Furthermore, compared to the traditional one (900–950 °C for 3–5 min), the optimized hot stamping process of 930 °C × 2 min were performed on Castrip sheet by industrial plat die quenching process and real hot stamping part, which still reached 1500 MPa grade.

High carbon pearlitic steel wires are widely used in the industry, such as for producing tyre cords and steel cables due to its excellent mechanical properties. Cold drawing is a crucial step in steel wire production. Due to the loading state during the cold drawing process, pearlitic wires tend to exhibit a <110> fiber texture. The non-uniform texture distribution on the cross-section of steel wires has been observed experimentally. The mechanisms yielding this non-uniformly distributed texture are carefully investigated in this study using a multi-scale computational approach. Firstly, a macroscale finite element model is established to simulate the deformation behaviour of pearlitic steel wires during cold drawing, with the aim of thoroughly investigating the inhomogeneous elastic-plastic deformation behaviours. Secondly, the macro mechanical responses are incorporated into the mesoscale representative volume element model as boundary conditions to comprehensively study the effect of inhomogeneous deformation characteristics on texture formation. The results present a significant advancement by revealing that the non-uniform texture distribution in a steel wire can primarily be attributed to the multiaxial stress state on the cross-section. Notably, at the center of the steel wire, the maximum principal stress aligns with the drawing axis, resulting in a dominant <110> fiber texture. Conversely, at the subsurface, the maximum principal stress progressively shifts towards the circumferential direction, yielding an evolving texture characterized by a {110}<110> circumferential texture. Furthermore, the research uncovers a crucial finding that it is the {110}<110> circumferential texture that significantly weakens the torsion ability of the wires. This is due to the limited activation of slip systems, marking a key advancement in understanding the mechanical properties of steel wires.

Coating adhesion and friction properties are critical for the utilization and maintenance of de-painted surfaces. This study utilized the "low-temperature processing" characteristic of ultraviolet picosecond lasers for the nondestructive removal of coatings on aluminum alloys, facilitating environmentally friendly paint stripping and subsequent applications. By adjusting laser fluence, surface morphology, chemical properties, and interface characteristics were evaluated, and temperature monitoring during the cleaning process was conducted to elucidate the cleaning mechanism. The results indicated that a laser fluence of 1.30 J/cm² is the threshold for complete coating removal. The fully stripped substrate exhibited surface roughening, slight oxidation, and polarization, which enhance wettability. This improved wettability, in turn, increases coating adhesion and wear resistance. Temperature monitoring results revealed a minimal photothermal effect during the ultraviolet picosecond laser cleaning process, ensuring the substrate remains intact. The de-painting mechanism primarily relies on the photochemical effect, enabling paint removal at low temperatures.