Interface Of Sheets Research Articles

Hot Powder Bed Compaction: A Rapid Fabrication Approach for Thermoplastic Composite Components

Traditionally thermoplastic composite prepreg fabrication methods often rely on molds or costly tooling, limiting the agility and efficiency of the fabrication process. A compelling need for a high-performance thermoplastic composite prepreg fabrication approach that eliminates the dependence on molds, simplifies the fabrication process and accelerates prototyping, enabling rapid iterations in product development. The proposed hot powder bed compaction (HPBC) technique eliminates the need for specialized molds and still provides fully consolidated components. The HPBC process involved a three-step sequence comprising powder densification, heating, and consolidation stages. These stages help effectively control time–temperature-pressure parameters to achieve good fusion between the prepreg sheets. This paper showcased the HPBC process on a hinge bracket made from glass fiber-reinforced nylon prepreg sheets to illustrate its performance. Experimental mechanical characterization was carried out on treated HPBC coupons and compared with the molding process. Notably, the experimental flexural test results indicated a flexural modulus of 13.79 GPa and flexural strength of 295 MPa for HPBC-treated specimens, placing them in a comparable range with molded components. Microscopy analysis revealed the complete fusion interface of the prepreg sheets, and DSC analysis shows increases in crystalline fraction from 31.5 % to 44.1 % in PA6. Hence, the HPBC process presents a versatile and effective approach for fabricating high-performance, complex-shaped, void-free, components using thermoplastic composite prepreg.

Effect of adhesive on friction stir spot welding of AZ31B magnesium alloy sheets

ABSTRACT AZ31B magnesium alloy sheets were lap-joined with adhesive only, friction stir spot welding (FSSW) only, and also with FSSW after adding adhesive between sheets. The produced joints were comparatively studied regarding joint cross-section geometrical features and defects that occurred at joint interface, microstructure, microhardness, tensile shear strength, and fracture surface evaluation. For joints made with FSSW only, cracks formed at underside of top sheet just above interface of sheets. However, joining with FSSW while there is adhesive between sheets eliminated formation of cracks and enabled weld width to enlarge significantly. Additionally, adhesive presence at interface of sheets joined by FSSW drastically reduced hook defect formation in the weld . The hook sizes of joints of FSSW with adhesive were so small as to be negligible compared to those of FSSW adhesive-free. Consequently, joints of FSSW with adhesive had much higher tensile shear strength. However, due to their brittle fracture, they displayed much less ductility than adhesive-free FSSW joints. The joints made via just adhesive had the lowest strength and elongation. Microstructure and microhardness of joints made by FSSW without and with adhesive were slightly different from each other. The main factors determining joint strength were adhesive, hook and weld size.

Consumable pin-friction stir spot welding of Al-Mg-Si alloy via pre-created hole and refilling: Microstructure evolution, defects, and shear/tensile failure load

Since Al-Mg-Si alloys are widely used in the transportation industry, it is important to produce a sound and robust weld between the sheets of these alloys. The focus of this work is on the tensile-shear and cross-tension strengths of the consumable pin-friction stir spot welds (CP-FSSWs) without an exit-hole between the Al-6061 aluminum sheets. Before welding, a hole was created at the joint region in the base sheets and then, it was filled using a rotating consumable pin. The tensile-shear, cross-tension, and microhardness tests were employed to evaluate the mechanical properties of the spot welds. The results showed that the pre-created hole was entirely filled during the welding process. While a complete bond was formed between the consumable pin and the lateral surface of the hole, there were three distinct regions at the interface of the pin and the bottom of the hole: complete bond, kissing bond, and defects. Enhancement of the tool rotational speed decreased the area of the complete bond in the weld compared to the other regions. A linear relationship existed between the bonding area and weld failure load in the cross-tension test. The proposed relationship approved the impact of the swirly region at the interface of the base sheets on the weld strength. While in the cross-tension test, the weld failure load decreased from ∼2800 to ∼1950 N, it improved from ∼10,500 to ∼12,000 N in the tensile-shear test with enhancement of the tool rotational speed from 700 to 2000 rpm. The hardness measurements demonstrated that there was no common heat affected zone softening after CP-FSSW.

Large amplitude vibration of sandwich beams with GPLRC face sheets and porous core under moving load

The nonlinear vibrational characteristics and responses of sandwich beams with graphene platelets reinforced composite face sheets and porous core (GPLRC-FS-PC) subjected to a moving load is studied. Each individual layers are manufactured by uniformly distributing and randomly orienting graphene platelets (GPLs) in a metal matrix. The kinematic relations of face sheets and core layer are developed separately based on the first-order shear deformation theory (FSDT) and by employing the geometric continuity at the interface of the face sheets and core layer. The Green’s strain tensor under the von Kármán nonlinear geometric assumptions is used. The spatially discretized motion equations are derived using the Ritz method with Chebyshev polynomials multiplied by suitable boundary functions as its basis functions. The obtained nonlinear motion equations are solved by employing the Newmark and Newton–Raphson methods. After the approach is validated, parametric studies are conducted to investigate the influences of the load velocity together with the geometric parameters and material properties on the sandwich beam responses. The results indicate that the porosities softening effects depend on their distribution patterns and addition of a very small amount of GPLs, increases the overall beam stiffness significantly. It is also found that the critical load velocities may increase when increasing the porosity coefficient.

Fretting Fatigue as a Limiting Factor on the Durability of Friction Stir Welded Lap Joints Using AA2099-T83 and AA2060-T8E30 Aluminium Alloys

Friction stir welding (FSW) has been proposed as an alternative modern joining technology and demonstrated important benefits for the manufacturing of efficient and lightweight aircraft structures using high-strength aluminium alloys. These structures are required to be corrosion- resistant and thus, it is necessary to use technologies such as surface treatments and sealants in their manufacturing and assembly. In this work, the feasibility of combining innovative Cr-free surface treatments, sealants and FSW technology was investigated with the focus on the durability of the joints in fatigue. FSW lap joints were produced using AA2099-T83 extrusions and AA2060-T8E30 sheets in the as-received or surface-treated condition. A sealant was also applied in some cases at the overlapping interface before the FSW process. Static tensile tests and fatigue tests were carried out applying hoop-stress loading conditions. Different fracture modes were identified depending on the stress levels applied in the fatigue tests: High stress levels resulted in fractures in the HAZ of the FSW joints, while the specimens tested at low stress levels showed fractures out of the FSW joint. In general, FSW joints produced using surface-treated aluminium components and sealant presented improved fatigue life and extended durability in comparison with non-treated aluminium joints. The surface treatments and sealant at the interface of AA2099-T83 extrusions and AA2060-T8E30 sheets reduced the friction and local damage produced due to the sliding movement during the fatigue tests, minimizing the fretting fatigue effect, which was found to be the main limiting factor on the durability and fatigue life of the FSW joints.

Evaluation of nanocomposite structure printed by solid-state additive manufacturing

Properties of polymer-metal hybrid structure printed by fed friction stir additive manufacturing (FFSAM) were evaluated. FFSAM is advanced solid-state additive manufacturing for the printing of macro-scale components for large stress-bearing situations. With the FFSAM, layer by layer printing of polymer and metal sheets convert to paste phase and join together as a uniform structure. With this process, during printing of hybrid structure, nanocomposite polymer is injected at the interface of base materials to fill voids and recover properties of the polymer matrix: polypropylene (PP) and stainless steel (SS) fabric selected as raw materials. During the printing process, Fe2O3 nanoparticles fed into the interface of PP and steel sheets. The mechanical and metallurgical characterization of printed [email protected]@Fe2O3 nanocomposite structure is evaluated. Macrostructure, tensile strength, hardness, and thermo-chemical properties of the printed structure were assessed and discussed. The result indicated that the In-situ feeding mechanism improves the physical and chemical properties of the printed structure. Reasonable properties achieved due to minimizing shrinkage gap in polymer side and improving sealing adhesion at interfaces of printed materials.

Ice Thickness From Deep Learning and Conditional Random Fields: Application to Ice-Penetrating Radar Data With Radiometric Validation

Identifying the location of the ice-bedrock interface of glaciers and ice sheets is crucial for a wide range of geophysical applications, such as searching for liquid water in basal regions and computing ice thickness to quantify ice sheet and glacier mass balance. Simple, record-by-record, approaches to detecting the bottom of the ice echo may be affected by spurious off-nadir noise that requires significant manual interaction to correct. In this paper, we propose a deep learning model based on convolutional neural networks (CNNs) and continuous conditional random fields (CCRFs) to automate ice bed identification and better capture fine-grained basal detail. We deploy this approach on HiCARS radargrams, the first time deep learning methods have been applied to this dataset. Intuitively, our CNN captures the global geometry of the ice bed, while the CCRF adjusts initial CNN outputs to better incorporate fine-scale spatial information into the final prediction. We also develop a coherent geophysical framework using three echo characters (along-track continuity, relative delay, and signal coherency) to compare our model’s outputs with those of a manually targeted approach. Our analysis suggests that our CNN + CCRF model is as suitable as the manual approach for radiometric applications, and it outperforms the manual technique in identifying the first continuous return, which is most often the near-nadir reflection. Thus, our approach is more universal than the current manual labeling methodology in the range of geophysical applications where it can be used, and it provides better confidence regarding the source of the basal return detected.

Laser-TIG welding of galvanized steel – numerical and experimental assessment of the effect of arc in various setups

The technology of laser-TIG welding utilizes the arc as a secondary heat source during laser welding. In TIG-leading configuration, the low-current arc precedes the beam to preheat the material. The numerical simulations representing various setups combining laser and arc were performed to study the changes of thermal cycles on the interface of thin metal sheets of overlap joint. The relations between the position of the arc towards the beam, additional heat input, and temperature gradients are discussed. The technology of laser-TIG welding of zinc-coated deep-drawing steel was experimentally applied in the same joint configuration. A good agreement between the calculated and experimental welds was achieved. The arc current less than 40 A did not cause the vaporization, neither oxidation of zinc coating on the interface surface of metal sheets. Nevertheless, the quality of laser-TIG welds was better compared to laser welds. The 40A arc current increased the heat input by about 50% and led to an almost 60% decrease in cooling rate compared to autonomous laser welding. Prolonged heating and cooling time are the key factors of improving the weld quality.

Comparative assessment on weldability of Al 6061 to polycarbonate for dissimilar sheets placement in friction stir lap welding using sensor signals

The thermoplastic polymers and precipitation hardened aluminium alloys are highly popular in the aerospace and automobile sectors as a replacement of metallic materials to improve the strength to weight ratio. Thus, the unlike aluminium alloy to polycarbonate assembled structures are often necessary for which mechanical fastening and adhesive bonding are the primary methods for joining as fusion welding processes are inadequate. However, the dissimilar joint efficiency is found to be less. Thus, the ultrasonic and friction welding processes are developed. The friction stir welding is one such advanced material stirring technique without any melting of base materials. The present work addresses metallic aluminium (Al6061) to polycarbonate sheet materials joining using friction stir welding in overlap configuration using tapered H13 tool steel. The thrust force with associated tool stirring torque has been acquired in real time during plunging followed by welding phase. The weld bead profile with respective force-torque signals was analysed for the process monitoring. The tensile test has been carried out on the lap welds. The weld interface of the unlike sheets have also been scrutinised. Initially, the aluminium sheet was partially overlapped on polycarbonate for the parametric study. The highest joint efficiency was found to be 40.2% at 1400 rpm tool rotational speed and 75 mm/min traverse speed due to improper material mixing at the weld interface. Therefore, the feasibility of the process have been tested by placing thermoplastic polycarbonate over aluminium alloy through which the joint efficiency was further improved (48.57%) at comparatively low tool rotational speed (1100 rpm) with lower welding speed (55 mm/min) as the minute metallic particles uniformly mixed with melted and solidified polycarbonate due to more uniform torque in the welding phase. The tool stirring torque and axial thrust was found to be higher in this overlap position.

Microstructure and mechanical properties of Al/Mg/Al composite sheets containing trapezoidal shaped intermediate layer

In the present study, the Al 6061/Mg ZK60/Al 6061 composite sheets with the trapezoidal shaped intermediate layer were successfully obtained by multi-pass hot roll bonding. The microstructure and mechanical properties of the composite sheets under different rolling passes were investigated. The results demonstrated that the interface of the composite sheets achieved the strong interface metallurgy bonding, without discernible voids, cracks, and other defects. The introduction of the three-dimensional (3D) interface layer significantly improved the interface bond strength of the composite sheets. The interface layer composed of Al3Mg2 and Al12Mg17 was observed at the interface of the composite sheets. The thickness of the intermetallic compounds (IMCs) layer varied with the position of the interface, and the IMCs layer was the thinnest near the center of the sheet. The IMCs layer was continuously coarsening and fragmenting with the increase of rolling deformation, and stress concentration was easily generated at the interface between the Mg layer and the Al layer, so the crystal grains were more refined than that inside of the component sheets, which made the actual strength of the composite sheets higher than the theoretical strength. With the proceeding of the rolling process, the internal grain size of the component sheet gradually increased, and the interface products were coarsened and fragmented, which reduced the tensile properties of the composite sheets. The interface layer with moderate thickness and intact interface layer in the composite sheets appeared uniformly broken when it was under tensile stress, and the direction of microcracks generated was perpendicular to the tensile direction, which hindered the crack propagation and delayed the fracture of the composite materials and thereby enhanced the elongation of the composite sheets. Simultaneously, the trapezoidal shaped intermediate layer made the cracks deflect along the interface, which was conducive to the strengthening and toughening of the interface area, to improve the plasticity of the composite sheets.

Control and optimization of bulge defect in incremental forming of cu-Al bimetal

The bimetal sheets products obtained by the incremental forming are gradually widely used because of the excellent properties of the bimetal sheets. But the forming process of the bimetal sheets is more complicated than that of single metal sheet because this process involves a complicated interface of the bimetal sheets. A three-dimensional model including the tool, the bimetal sheet and the cohesive element between the bimetal sheet has been suggested to discuss the bulge defect affecting the accuracy of incremental forming. And the analysis results have been compared with the experiment results to verify the correctness of the simulation model. The analysis show that the reason of bulge defect is the inconsistent stress state on the upper and lower surfaces of the sheet. Moreover, the results also indicate that the step down size is the most critical factor affecting the bulge height, the height of bulge defect increases by 133% as the step down size increase. In addition, it is found that different parameters also have a great impact on the interface status of the bimetal. Effecting optimization parameter have been proposed to reduce the bulge defect by 53%.

Influence of Microstructure in Near‐Surface Areas of Feedstocks on the Bond Strength of Roll Bonded Aluminum Clads

This work determines the impact of the different grain sizes and oxide layers in near‐surface areas of aluminum semi‐finished products on the bond strength after warm roll bonding. To adjust the grain microstructures in the initially twin‐roll cast feedstocks, they are differently treated to generate different grain sizes in the near‐surface areas. Semi‐finished products of the same near‐surface microstructure are then joined by warm roll‐bonding. In industrial applications, it is common to influence the bond strength of clads by applying a post heat treatment. Therefore, a part of the samples was annealed after warm roll bonding. Post‐treated samples with coarser grain size exhibit up to two times higher peel strength than untreated samples. Higher peel strengths of the post‐treated samples can be explained both by improved diffusion bonding due to heat exposure, and by recrystallization and grain coarsening of microstructure in the interface of sheets. Increase in peel strength of the composites made of feedstocks with coarser grains can be the result of stronger grain rotation, which damages oxide layer on the interface. To summarize, twin‐roll cast and soaked material with the coarsest grains in the near‐surface areas is the best feedstock for roll‐bonding, if an additional heat treatment is applied.

Microstructure and its hardness estimation of resistance spot weld of ultra-high strength steel sheets: development of resistance spot welding with pulsed current pattern for ultra-high strength steel sheets

ABSTRACT A new resistance spot welding process with ‘pulsed current post-heating pattern’ is developed for improving joint strength of ultra-high strength steel (UHSS) sheets. This post heating process consists of short-time high-current post-heating (pulsed current) and short-time cooling, which utilizes the phenomenon that the pulsed current reheats especially near the outer peripheral regions of the contact area of electrode/steel interfaces and faying interface of steel sheets. The strength improvement can be obtained owing to two effects; the reduction of solidification segregation in the nugget and the appropriate softening of the heat affected zone (HAZ). Toughness of the nugget increases with alleviating segregation of embrittling elements. Properly widened and softened HAZ would lead to large plastic deformation, which could reduce stress concentration at the edge of the nugget on the faying interface and prevent brittle fracture in the nugget during straining. This study aims to elucidate the microstructural change in the HAZ due to the pulsed post-heating current pattern and its effect on hardness profiles, and to propose an estimation method of HAZ hardness. 1180 MPa grade ultra-high strength steel sheet consisting of ferrite and martensite was used. Softened region was fairly widened with decreasing its minimum hardness when applying the pulsed current post heating. No significant difference was observed in the region where the maximum temperature is over Ac1 between with and without the pulsed current post heating pattern. This would be because the maximum temperature was the same in these regions even when applying the pulsed current. The HAZ was widened in the region where the maximum temperature was lower than Ac1. These regions have the same fractions of martensite and ferrite as the steel sheet before welding, but the martensite was much tempered when applying the pulsed current pattern. These tempered phenomena of the martensite can be well estimated using an accumulated tempering parameter for both tempering martensite and autotempering behaviour of martensite formed during cooling after welding.

Adsorption of 1,4-phenylene diisothiocyanate onto the graphene oxide sheets functionalized with polydiphenylamine in doped state

Adsorption processes of 1,4-phenylene diisothiocyanate (PDITC) on two new platforms of the type graphene oxide (GO) sheets and GO layers functionalization with polydiphenylamine (PDPA) are studied by Raman scattering and photoluminescence (PL). An interaction in solid state phase of the two constituents, i.e. PDITC and GO sheets, and a deposition of PDITC onto the PDPA functionalized GO layers, respectively, by the drop casting method, were performed. In the first case, it is shown that interaction in solid state phase of GO with PDITC leads to an intercalation of the organic compound between GO sheets simultaneously with the appearance of the o-thiocarbamate groups, that induces: (i) an enhancement of the PDITC Raman lines situated in the 400–800 and 1000–1300 cm−1 spectral ranges, (ii) a change in the ratio between the relative intensities of the two Raman lines peaked at 1585 and 1602 cm−1 accompanied by an up-shift in the case of the second line and (iii) a down-shift of the PDTIC PL band from 502 to 491 nm. Using cyclic voltammetry, an electrochemical functionalization of the GO layers with PDPA doped with H3PMo12O40 heteropolyanions takes place, as demonstrated by Raman scattering and FTIR spectroscopy. The presence of the amine groups in the molecular structure of the doped PDPA functionalized GO layers induces a chemical adsorption of PDITC on this platform, when the thiourea groups appear simultaneously with o-thiocarbamate groups. A chemical mechanism is proposed to take place at the interface of the GO sheets and the doped PDPA functionalized GO layers, respectively, with PDITC.

A novel method for the fabrication of Al-matrix nanocomposites reinforced by mono-dispersed TiAl3 intermetallic via a three-step process of cold-roll bonding, heat-treatment and accumulative roll bonding

A novel method to fabricate aluminum metal-matrix composites reinforced by mono-dispersed TiAl3 intermetallic particles, by cold-roll bonding, heat treatment, followed by accumulative roll bonding (ARB), is demonstrated. Roll bonding of 1100-Al sheets inserted with Ti powder was carried out at room temperature with 50% thickness reduction. Complete conversion of the initial Ti particles into TiAl3 intermetallic was achieved by a post-rolling annealing treatment at 590 °C for 2 h, which results in the formation of coarse TiAl3 particles along the interface of the original 1100-Al sheets. Subsequent ARB process was applied to break up and disperse the TiAl3 phase, and after 5 cycles of ARB, an aluminum-matrix composite with mono-dispersed TiAl3 particles of submicron sizes was achieved. The Al matrix also undergoes dynamic recrystallization during the ARB process to result in a fine-grained microstructure (size less than 500 nm). The hardness, tensile strength and elongation of the Al/TiAl3 composite were found to increase with the number of ARB cycles. The tensile strength of the Al/TiAl3 composite after the 5th cycle reaches 400 MPa, which is significantly higher than the 300 MPa of monolithic 1100-Al processed in the same way. The tensile elongation of the Al/TiAl3 composite after 5 cycles of ARB exhibits a good value of ∼8%, with a ductile fracture mode. This is the first successful attempt to achieve Al-matrix nanocomposites reinforced by mono-dispersed TiAl3 intermetallic based on an ARB method.

Suppressed deformation instability in the twinning-induced plasticity steel-cored three-layer steel sheet

Deformation instabilities (i.e., yield point phenomenon (YPP) and serrated flow) were investigated for twinning-induced plasticity (TWIP) steel-core with low-carbon (LC) steel outer layer sheets. During tensile tests, both the YPP and serrated flow were suppressed as the volume fraction of the TWIP steel-core decreased. Electron backscattering diffraction analysis indicated that a strain gradient was induced, and that geometrically necessary dislocations (GNDs) accumulated at the TWIP-LC steel interface. With increase in the dislocation density by plastic deformation, the deformation instabilities in the TWIP-cored layer steel sheets were suppressed due to the reduced probability of interaction of dislocation with carbon-solutes. This result indicates that the strain gradient at the interface of the layered sheets not only enhances the mechanical property, but also suppresses deformation instability.

Microstructure and Tensile-Shear Properties of Resistance Spot-Welded Medium Mn Steel

The medium Mn steels are gaining increasing attention due to their excellent combination of mechanical properties and material cost. A cold-rolled 0.1C5Mn medium Mn steel with a ferrite matrix plus metastable austenite duplex microstructure was resistance spot-welded with various welding currents and times. The nugget size rose with the increase of heat input, but when the welding current exceeded the critical value, the tensile-shear load increased slowly and became unstable due to metal expulsion. The fusion zone exhibited a lath martensite microstructure, and the heat-affected zone was composed of a ferrite/martensite matrix with retained austenite. The volume fraction of retained austenite decreased gradually from the base metal to the fusion zone, while the microhardness presented a reverse varying trend. Interfacial failure occurred along the interface of the steel sheets with lower loading capacity. Sufficient heat input along with serious expulsion brought about high stress concentration around the weld nugget, and the joint failed in partial interfacial mode. Pull-out failure was absent in this study.

Effect of surface nitridingtreatment in a steel plate on the interfacial bonding strength of the aluminum/steel clad sheets by the cold roll bonding process

Steel sheets (08Al) with nitriding treatment and with normal wire brushing surface preparation were bonded with aluminum alloy (4A60), respectively, by cold roll bonding (CRB) process. The interface of clad sheets and the surface of the component metals after peeling off were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The peel strength of the two types Al/steel clad sheets was evaluated by peeling test. The experimental results indicated that a homogeneous Fe3N hardened and brittle layer with an average thickness of 10µm formed on the surface of steel layer subject to salt bath nitriding treatment. More cracks and gapes formed at the interface of the Al/nitrided St clad sheets than those at the Al/brushed St clad sheets during the CRB process. The degree of contact and the bonded surface area in the Al/nitrided St sheets is higher than those in the Al/brushed St sheets at a given reduction, contributing to the enhancement of bonding strength in the former case. Meanwhile, the peel strength of the Al/nitrided St clad sheets is higher than that of the Al/brushed St clad sheets, reaching 15.9N/mm and 10.9N/mm, respectively, at the same reduction of 60%. In addition, the bonding mechanism of the Al/nitrided St clad sheets is discussed and it is consistent with the film theory.

Effect of the filler amount on the optical absorption properties and the surface features of polymeric joints based on biomedical UHMWPE welded by a Nd:YAG laser

Polymeric materials can be welded by the laser transmission welding technique in order to join two or more sheets. At the interface of the polymer sheets, the released energy induces melting that is assisted by pressure, producing a fast and resistant welding. In this research, single-lap polymeric joints of biomedical ultra-high molecular weight polyethylene sheets were realized; one of the two polymer sheets was doped, at different concentrations, with carbon nanomaterials as a laser absorbent filler. A pulsed neodymium-doped yttrium aluminium garnet laser operating in the wavelength of 532 nm and of 1064 nm with an intensity of the order of 109 W/cm2 was employed to obtain a joint at the interface between the transparent polymer and the absorbent one. The mechanical shear resistance of the prepared joints was related to the optical absorption feature of the polymeric materials. Besides, surface analyses such as hardness, roughness and wettability in different inorganic and organic fluids were presented and discussed. The result of characterization analyses indicated the best filler amount in order to have a mechanically resistant joint with surface properties also suitable for the biomedical employment.

W18O49 nanowires grown on g-C3N4 sheets with enhanced photocatalytic hydrogen evolution activity under visible light

A hybrid nanomaterial comprising of one-dimensional W18O49 nanowires grown on two-dimensional g-C3N4 sheets was prepared by a facile solvothermal process. Photocatalytic activity of these materials for H2 generation under visible light was evaluated. The optimum efficiency of W18O49/g-C3N4 composite photocatalyst at a mass content of 30% was up to 4.5 times as high as that of the pure g-C3N4. The significantly enhanced performance of W18O49/g-C3N4 composites was mainly attributed to the synergistic effect between the interface of W18O49 nanowires and g-C3N4 sheets, involving stronger light absorption in the visible range, faster transfer and more efficient separation of the photo-generated electron-hole pairs. In short, the W18O49/g-C3N4 hybrid nanomaterial was demonstrated to be an effective photocatalyst for H2 production.