Internal flow channels fabricated by additive manufacturing and precision casting are widely used in aerospace, hydraulic, medical, and heat transfer systems, where surface integrity critically affects flow efficiency and service reliability. However, as-built channels typically suffer from high roughness and various manufacturing-induced defects, making post-processing an essential step for performance enhancement. This paper presents a systematic review of recent advances in internal flow channel finishing technologies, including electrochemical/chemical polishing (ECP/CP), abrasive flow machining (AFM), abrasive fluid jet polishing (AFJ), magnetic abrasive finishing (MAF), composite polishing strategies, and emerging hybrid methods such as HydroFlex. The fundamental mechanisms, process characteristics, and applicability of each technique are critically analyzed. ECP/CP provides high material removal efficiency but is limited by electrolyte management and cathode design complexity. AFM and AFJ offer flexible access to internal geometries but suffer from flow instability, abrasive control challenges, and equipment cost issues. MAF demonstrates strong adaptability to complex structures and environmentally friendly processing but is constrained by magnetic field penetration and geometric accessibility. To overcome the limitations of single processes, composite and field-assisted techniques have been developed to enhance material removal uniformity and process stability. Emerging methods further integrate mechanical, fluidic, and magnetic interactions to improve adaptability to complex internal topologies. Finally, current challenges and future research directions are discussed, highlighting the development trends toward intelligent process control, multi-field coupling, sustainable manufacturing, and high-precision adaptive polishing for complex internal channels.

In718 has found extensive applications in the aerospace and petrochemical sectors attributed to its excellent high-temperature strength, corrosion resistance, etc. Subtractive manufacturing of In 718 generates large amounts of cutting chips, making chip recycling crucial. This study prepared regenerated powder through ball milling (BM) and compared the clad morphology and micromechanical properties by regenerated powder and gas atomized (GA) powder with same size of 53-150 um. The results showed that both powders underwent a microstructural transition from columnar to equiaxed grains, while the gas atomized powder produced a finer grain structure in contrast to chip regenerated powder. The clad produced from chip regenerated powder exhibited a more favorable coating morphology, characterized by a smaller cladding angle and better flowability, which further facilitated gas escape. Due to the irregular morphology of the chip regenerated powder, its low packing density resulted in a thinner clad track, leading to an increased dilution rate. The micro-hardness of the clad track with chip regenerated powder was 7.68% lower than that of gas atomized powder. The study further investigated how powder particle size and laser power influenced the clad properties. It was found that the particle size had a more pronounced impact on the properties of the clad track than laser power. Moreover, a higher laser power was required as the particle size increased to achieve adequate cladding quality. Based on this study, the most suitable cladding conditions for the chip regenerated powder were obtained.

To address the synergistic degradation of corrosion and wear in marine environments, CoCrFeNiAlMo/xSiC high-entropy alloy gradient composite coatings (x = 0%, 5%, 10%, and 15%) were fabricated on Q235 steel via laser cladding. The influence of SiC content gradient on the microstructure, mechanical properties, and tribocorrosion behavior of the coatings was systematically investigated. The results show that the coatings exhibit good metallurgical bonding with the substrate, featuring a continuous compositional gradient along the thickness direction, a dense microstructure, and no observable defects. With increasing SiC content, the microstructure evolves from columnar to cellular and equiaxed grains, accompanied by pronounced grain refinement, while the phase constitution transforms from FCC + BCC to FCC + BCC + carbides. EBSD analysis reveals that grain refinement and increased grain boundary density promote dislocation accumulation at grain boundaries, leading to a more homogeneous strain distribution and enhanced structural stability. Mechanically, the microhardness increases with SiC content, whereas the flexural strength gradually decreases. Electrochemical results indicate improved corrosion resistance, reaching an optimum at 10% SiC, attributed to the enhanced stability of the passive film. The charge transfer resistance decreases by approximately 43.18% compared with the SiC-free coating. Tribological tests show that the wear rate decreases with increasing SiC content, reaching 2.84 × 10-7 mm3·mN-1 at 15% SiC, a reduction of ∼ 73.70%, while the wear mechanism transitions from adhesive to abrasive wear. The gradient design achieves a synergistic improvement in wear and corrosion resistance through SiC dispersion strengthening, grain refinement, and passive film stabilization.

The ultrasonic surface rolling process (USRP) is a chip-free, thermally inert technique that enhances material surfaces by inducing plastic deformation, grain refinement, and residual compressive stress. While conventional ultrasonic rolling devices (CURD) are typically single-sided, their application to slender shafts-due to low structural stiffness-often results in uneven pressure distribution and reduced surface uniformity. To address these limitations, this study proposes a novel slender shaft ultrasonic rolling device (SSURD) designed for dual-sided, stable processing. Experimental results demonstrate that SSURD significantly improves surface properties: for SET1 samples, surface roughness decreased by 91.8

Cemented carbide is a typical difficult-to-machine material used in machine tool components. The grinding process is an effective method for achieving the desired shape and dimensional accuracy of cemented carbide parts. The deformation mechanisms and damage behavior of the ground surface depend on the grinding parameters. In this study, WC-Al0.5CoCrFeNi high-entropy cemented carbide (WC-HEA) was fabricated via vacuum gas-pressure composite sintering. Grinding experiments were conducted to analyze the phase composition, microstructure, deformation mechanisms, and damage behavior of the ground surface. A refined surface layer composed of both amorphous and nanocrystalline phases formed on the machined surface. The dominant damage behavior of WC grains within the refinement layer was fracture and microcracking. The severity of brittle damage and binder-phase deformation on the ground surface increased with grinding depth and feed rate. Under a high grinding strain rate, grain pull-out, brittle fragmentation, and cracking were reduced. Therefore, the surface exhibited lower roughness and fewer brittle damage defects. In addition, elevated strain rates promoted a deformation mechanism in the Al0.5CoCrFeNi binder phase, characterized by twinning and solid-state amorphization. This plastic deformation mechanism suppresses phase transformation defects. The findings of this study clarify the deformation mechanisms and damage behavior of WC-HEA under various grinding parameters, providing a theoretical basis for the efficient and high-quality processing of WC-HEA.

Grinding sintered high-entropy cemented carbides is an effective method to improve the geometrical accuracy of parts. The high-force-thermal coupling effect leads to microstructural changes near a material's surface, which in turn affects the material's mechanical properties. In this study, WC-Al0.5CoCrFeNi specimens were prepared using gas pressure sintering technology. To better show the microstructural evolution mechanisms during the grinding process, the researchers used various complementary characterization techniques to observe the phase composition, texture, microstructure, and mechanical properties of specimens before and after grinding. The results indicated that the surface of the ground specimens formed a gradient microstructure, with gradient variations in dislocation density, grain size, and grain boundary distribution. High-density dislocations and amorphization dominated the plastic deformation of the specimens. Dislocations, stacking faults, and lattice distortions were observed at the grain boundaries of the high-entropy alloy (HEA), which are prerequisites for amorphization. Because HEAs were added, the defects in the ground high-entropy cemented carbide were significantly fewer than those in traditional hard alloys. In addition, nanoindentation experiments indicated that surface defects and grains sliding together contributed to a slight degradation in mechanical properties after grinding. The study results help to understand surface damage induced by machining during usage.

The new type of composite magnetic abrasive was developed using hydroxyl iron powder as the matrix, Al2O3 and SiC as the abrasive phases, and Mn as the sintering additive. The grinding performance of the composite abrasives were systematically investigated using single-factor magnetic abrasive polishing experiments. The findings revealed that the addition of Mn substantially enhanced the bonding between the iron matrix and abrasive particles, compared with the composite magnetic abrasive without Mn added, the saturation magnetisation reached 128.18 emu/g, increasing by 5.4 %, and the coercivity decreased to 22.25 Oe, reducing by 8.3 %. In the magnetic abrasive polishing of 304 stainless steel pipe interiors, the surface roughness decreased from 572 nm to 333 nm, resulting in a considerable reduction in surface defects, including pits and scratches. Comparative experiments demonstrated that the developed abrasives exhibited over 30 % higher polishing efficiency than conventional abrasives, with no apparent detachment of abrasives following wear, suggesting a prolonged service life.

WC/HEA cemented carbides with CoCrFeNiTi HEA as the binder phase were prepared by a low-pressure sintering method after mechanical alloying. The effects of HEA and fine WC content on the microstructure and mechanical properties of WC/HEA cemented carbides were investigated. It is found that the diffusion retardation effect of HEA effectively refined the WC grains, but excessive HEA resulted in the formation of a dendritic structure, causing an uneven microstructure. When the HEA content was 10

316LN stainless steel (316LN SS) with a gradient structure was produced by ultrasonic surface rolling processing (USRP). The surface quality of the 316LN SS specimen was improved significantly after the USRP. The experimental results showed that with an increasing number of rolling passes, the thickness of the gradient structure layer increased, and the microhardness decreased in a gradient from the surface to the matrix. The results also indicated that the optimal parameters were as follows: 220 rad/min lathe speed, 0.11 mm rolling space, 0.2 rad/min feed rate, and 5 rolling passes. Under these parameters, the tested surface residual compressive stress (SRCS) value was nearly 32 times higher than that achieved after conventional processing on the surface of 316LN stainless steel. Moreover, the microstructure exhibits an increase in the subgrain boundary density and low-angle grain boundaries (LAGBs, misorientation < 15°) of the steel, providing an easy way to enhance the properties, including the mechanical and corrosion resistance of 316LN stainless steel.

Currently, the use of cutting fluid not only pollutes the environment, but also increases production costs. Therefore, dry cutting is becoming increasingly popular in metal machining. In this research, the effects of DLC self-lubricating coating and femtosecond laser texture on enhancing the dry cutting ability of an AlCrN-coated cemented carbide tool are investigated. These effects are very important for dry cutting applications and environmental protection. For this purpose, DLC/AlCrN coated tools with micro-texture were prepared by arc ion plating, laser technology and pulsed DC magnetron sputtering. The laser texture and the microstructure of the coating are evaluated using analytical tools. Through dry cutting experiments on quenched AISI5140 steel, the machining performances of different coated tools were compared. As a result, the dry cutting performance of the DLC/AlCrN coated tool is significantly improved, and the cutting force, cutting temperature, friction coefficient, and tool wear are significantly reduced compared with those of traditional AlCrN coated tools. A more important finding is that the dry cutting performance of the cutting tools is further improved due to the synergistic effect of the micron texture and the DLC coating. At high speed cutting (150 m/min), the cutting temperature is reduced by 19.1

Ultrafine-grained cemented carbides have superior mechanical properties, surpassing conventional cemented carbides in hardness, strength, and toughness. In this study, ultrafine-grained WC-6 wt% Co cemented carbides were prepared by the addition of VC powder. The impact of VC content and sintering temperature on the microstructure and physical-mechanical properties was systematically investigated. Through techniques such as transmission electron microscopy (TEM), the effect of VC on the average grain size of the alloy was analyzed in depth, and the inhibition mechanism of VC was summarized. The results show that VC addition markedly refines WC grains. When the VC content is 1.2 wt%, the alloy attains its minimum average grain size, approximately 129 nm, and the hardness is up to 2368.9 HV30. However, VC content exceeding 1.5 wt% results in abnormal grain growth and localized vanadium enrichment, adversely affecting the alloy's hardness and fracture toughness. At a sintering temperature of 1400 degrees C, VC most effectively retards grain growth. When the temperature rises to 1450 degrees C, grain coarsening accelerates, which lowers hardness but improves fracture toughness. At an optimal VC content of 1.2 wt% and the sintering temperature of 1400 degrees C, an ultrafine-grained cemented carbide with a relative density of 98.12 %, hardness of 2368.9 HV30, fracture toughness of 9.3 MPa & sdot;m1/2, and transverse rupture strength of 1205.8 MPa was obtained. These findings provide practical guidance for industrial production and application of ultrafine-grained cemented carbides.

Understanding the molecular and cellular mechanisms underlying complex traits in pigs is crucial for enhancing genetic gain via artificial selection and utilizing pigs as models for human disease and biology.Here,we conducted comprehensive genome-wide association studies(GWAS) followed by a cross-breed meta-analysis for 232 complex traits and a within-breed met a-analysis for 12 traits,using 28.3 million imputed sequence variants in 70 328 animals across 14 pig breeds.We identified 6878 quantitative trait loci(QTL) for 139 complex traits.Leveraging the Pig Genotype-Tissue Expression resource,we systematically investigated the biological context and regulatory me chanisms behind these trait-QTLs,ultimately prioritizing 14 829 variant-gene-tissue-trait regulatory circuits.For instance,rs344053754 regulates UGT2B31 expression in the liver and intestines,potentially by modulating enhancer activity,ultimately influencing litter weight at weaning in pigs.Furthermore,we observed conservation of certain genetic and regulatory mechanisms underlying complex traits between humans and pigs.Overall,our cross-breed meta-GWAS in pigs provides invaluable resources and novel insights into the genetic regulatory and evolutionary mechanisms of complex traits in mammals.

The number of teats is a critical reproductive trait in sows, exerting a direct impact on the survival rate of weaned piglets. Existing studies on selection signals associated with teat numbers in different strains of Large White pigs are scarce. We performed selection signal detection on three distinct strains of Large White pigs with 16 or more nipples: the French CG (Choice Genetics), the French Cooperl, and the Dutch Topigs. Our goal was to identify pivotal candidate genes contributing to the higher nipple count in Large White pigs. A comprehensive analysis, including CLR (Composite Likelihood Ratio), iHS (integrated haplotype score), and nSL (number of segregating sites by length) methods, alongside XP-EHH (Cross-population Extended Haplotype Homozygosity), was undertaken to identify genetic positive selection signatures in Large White pigs. Through our analysis, we identified six key candidate genes in the CG Large White pigs: DPP6, COL22A1, TRPC7, PROX1, ROR2, and ABCG1. In the Cooperl Large White pigs, the key candidate genes were PPARA, TRPC7, and NR3C1. In the Topigs Large White pigs, the key candidate genes were DOCK1, PCM1, and MRTFA. Among the aforementioned genes, PCM1 and DOCK1 have been identified as correlated with the number of teats in pigs, while TRPC7, DOCK1, and MRTFA have shown a significant link with teat number based on PheWAS (Phenome-wide association study) analysis. Our findings show that multiple genes associated with teat development in Large White pigs have experienced significant selection pressure throughout the breeding program. These results deepen our understanding of the progress in breeding Large White pigs and provide a valuable framework for their continued selection.

Vulva morphologies represent significant traits in pig production. Recent studies suggest that vulva size can be predictive of the reproductive performance of gilts. This study aimed to analyse the genetic parameters of vulva traits, including vulva length, vulva width, and vulva angle score (VAS), as well as litter traits, including total number born, number born alive, number stillborn, and piglet survival rate, across three Large White pig strains (PIC, Topigs, and Canadian). We estimated the correlations between vulva traits and litter performance, as well as the reasons for culling gilts. In this study, single-trait and multitrait models were employed to estimate the heritability and genetic correlations between vulva and litter traits. The heritabilities of vulva traits ranged from 0.167 to 0.426, whereas the heritability of litter traits ranged from 0.013 to 0.147. The VAS in Topigs Large White pigs exhibited the highest heritability. The genetic correlation coefficients between vulva length and width in PIC and Topigs Large White pigs were significantly positively correlated, ranged from 0.585 to 0.767. No significant correlation was found between vulva and litter traits. Subsequently, we scored the vulva traits according to previously reported studies, linear relationship analysis between vulva score and reasons for culling gilts revealed that gilts with larger vulva widths had a lower risk of culling. The average vulva width score of the gilts that were culled due to prolonged oestrus was significantly lower (2.75) compared to that of gilts with normal oestrus (2.90). In the population of gilts aged 220-230 days, the gilts with higher vulva angle scores had a lower risk of culling due to vulva inflammation with purulent discharge. The results suggest that selecting vulva traits in replacement gilts is an effective strategy to reduce gilt culling rates. (c) 2025 The Author(s). Published by Elsevier B.V. on behalf of The animal Consortium. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Longitudinal torsional ultrasonic vibrations with different longitudinal torsional ratios [Formula: see text] were introduced into the extrusion tapping process to explore the effects of ultrasonic vibrations in different vibration directions on extrusion tapping of small blind holes in Ti-6Al-4V. First, the motion trajectory model of longitudinal torsional ultrasonic vibration extrusion tapping (LT-UVET) was established, and the intermittent extrusion separation characteristics of edge teeth during the LT-UVET process were analyzed. In addition, finite element simulation was used to analyze the stress and torque of the LT-UVET process with different [Formula: see text]. The simulation results show that the effective stress and torque of LT-UVET at different [Formula: see text] are reduced compared with conventional extrusion tapping (CET). When the ultrasonic vibration direction coincided with the thread direction ([Formula: see text] = 0.08), the effective stress and torque were the lowest. A tapping experiment platform was built and two ultrasonic tools with different aspect ratios were used to conduct tapping experiments. Experimental results show that the torque of LT-UVET is significantly lower than that of CET. Among them, when [Formula: see text] = 0.08, the effect on torque reduction is more obvious. In addition, LT-UVET can also promote metal flow forming, reduce material accumulation, and improve thread surface integrity.

The finish process of a cladding layer has undergone an evolution of mechanical machining. An issue worth noting is that the machined surface exhibits different machining characteristics along the cutting speed and feed direction, i.e., surface anisotropy. However, conventional surface anisotropy evaluation parameters are based on the distribution of lays, while the determination of lays is related to their ratio to the contour height, which leads to inconsistent when using different machining methods. In present study, the evolution of surface anisotropy based on surface integrity/roughness and surface information entropy in a polar coordinate system from turning to burnishing was studied. The results indicated that the machined surface exhibited strong anisotropy especially along the feed direction with Std of 90°. However, all the surface anisotropy based on the radar diagrams of surface roughness Ra, Rz, Rvk, and Rpk were improved after subsequent burnishing. Moreover, the strengthening effect of subsequent burnishing deteriorated as a result of the weakening of severe plastic deformation when feed in pre-turning exceeds 0.4 mm/r. The radar diagram of surface information entropy also showed a trend of first increasing and then decreasing, indicating the improvement effect of the subsequent burnishing on surface anisotropy reached its maximum at f = 0.35 mm/r in pre-turning. The most important is that the surface integrity of the turning and burnishing process chain with considering machining efficiency reached its maximum value at a feed of 0.35 mm/r. On basis of this research, it is perspective to provide theoretical guidance for the remanufacturing of high-performance and high surface integrity parts.

BACKGROUND:After long-term artificial selection and lineage mixing, the Danish Landrace pig (DLR), has developed characteristics such as a long body length, high lean meat rate, rapid growth rate, high litter size, and a longer gestation period, with an average gestation length of 117 days. However, the genes responsible for these desirable traits remain partly unknown. According to the breeding history of DLR pigs, it has undergone introgression from British Large White pigs (BLW), selection for high lean meat rate and long body length within the population, and a rapid improvement in reproductive performance since 1992. Research on Danish Duroc and Large White pigs has detected that the lineage of pigs in Taihu Lake region (TL) has introgressed into these two breeds. Therefore, we performed resequencing and chip scanning on 106 TL pigs and 557 DLR pigs, and downloaded 163 resequencing data from Eurasian pigs for shared haplotype analysis, selective sweep analysis, and GWAS. RESULTS:The results indicate that 12 important genes, including CREB3L2, PRKAB2, HIF1A, IGF1, have introgressed from BLW into DLR pigs. These genes enhance lean meat percentage by participating in thermogenesis, oxidative phosphorylation and HIF-1 signaling pathways. In the DLR pig population, 13 shared selected genes were identified across three selective sweep methods. These genes including HBM, RHBDF1, POLR3K, ZNF484, were found to be associated with growth rate, body length, lean meat percentage, and reproductive performance by pheWAS analysis. Interestingly, reproductive performance is primarily related to gestational trait. GWAS for gestational trait in DLR pig population revealed 13 significant genes which also under selection in selective sweeps. These genes include INSYN1, NPTN, NEO1, ZDHHC21. Our study clarifies that the lineage of TL pigs has also introgressed into DLR pigs, with NDUFS4 being an important introgressed gene influencing reproductive performance. Moreover, compared to the low-fertility American Landrace pigs, HTR7, RPP30, ANKRD1, ARHGAP42, and CNTN5 may be important genes selected for enhancing litter size within the DLR pigs. CONCLUSIONS:Our research deepens the understanding of the breeding history of DLR pigs, preliminarily identifies genes associated with the characteristics of high lean meat percentage, long body length, and high fertility in DLR pigs, and also finds that the high litter size of DLR pigs may be related to gestation length.

Machining is one of the most commonly used post-processing techniques to enhance surface quality and mechanical properties of components fabricated by selective laser melting (SLM). The inhomogeneous microstructure resulting from the SLM process has a significant impact on machining-induced material responses within the affected layer. Turning trials were performed on SLMed IN625 nickel-based alloy by varying cutting speeds. Their metallurgical responses beneath the machined surface were characterized in terms of grain morphology, crystallographic structure, and element distribution. Experimental results show that the white layer consists of an amorphous structure produced under high cutting speeds over 48 m/min. Also, turning has a slight impact on the initial (001) texture evolution, and oxidation reaction is absent from the machined surface while showing elements redistribution. The findings offer insights into the visual understanding of microstructure evolution toward additively manufactured nickel-based alloy specimens as well as cutting parameters optimization subjected to post-turning operation.

In high-speed cutting, the shim-insert system is subjected to high-speed impact loads, and different stiffness of the shim-insert system exhibit varying impact responses at different load rates, which in turn affect the wear and damage of the inserts. This paper investigates the effect of load impact rate on the protective performance of weak stiffness shims. A mass-spring vibration model for the shim-insert system is established to analyze the effect of load rate on the inertial forces within the system. Finite element analysis is conducted to explore the influence of impact load rate on the stress distribution at the tool tip for four different shim stiffness levels. Additionally, intermittent cutting experiments using four different stiffness shims are performed to study the impact of load rate on cutting forces, vibration acceleration, and insert fracture under different cutting speeds (load rates). The results show that as the impact load rate increases, the protective effect of weak stiffness shims on the inserts gradually weakens. At low impact load rates, the shim reaction force dominates, and the inertial force of the insert can be neglected. As the load rate increases, the inertial force of the insert increases and becomes dominant, while the shim reaction force gradually diminishes. As the cutting speed increases (from 500 r/min to 900 r/min), the weak stiffness shim's ability to reduce cutting force weakens (from 13.44 % to 4.17 %), the inhibition of vibration acceleration amplitude decreases (from 40.47 % to 9.57 %), and the reduction in rake face damage diminishes (from 75 % to 11 %). Therefore, under high-speed impact, the protective effect of weak stiffness shims weakens, leading to a reduction in tool protection performance.