氨纶包缠纱的形变力学性能研究

通过拉伸应力-应变曲线研究氨纶包缠纱的形变力学性能,织物中的氨纶包缠纱在充分回复后,可满足弹性织物要求的形变性能,氨纶外侧包缠的非弹性纱赋予纱线足够的强度。

Effect of cold rolling deformation on microstructure evolution and mechanical properties of spray formed Al−Zn−Mg−Cu−Cr alloys

The impact of cold rolling deformation,which was introduced after solid solution and before aging treatment,on microstructure evolution and mechanical properties of the as-extruded spray formed Al−9.8Zn−2.3Mg−1.73Cu−0.13Cr(wt.%)alloy,was investigated.SEM,TEM,and EBSD were used to analyze the microstructures,and tensile tests were conducted to assess mechanical properties.The results indicate that the D1-T6 sample,subjected to 25%cold rolling deformation,exhibits finer grains(3.35μm)compared to the D0-T6 sample(grain size of 4.23μm)without cold rolling.Cold rolling refines the grains that grow in solution treatment.Due to the combined effects of finer and more dispersed precipitates,higher dislocation density and smaller grains,the yield strength and ultimate tensile strength of the D1-T6 sample can reach 663 and 737 MPa,respectively.In comparison to the as-extruded and D0-T6 samples,the yield strength of the D1-T6 sample increases by 415 and 92 MPa,respectively.

Effect of thermo-mechanical treatment on microstructure and mechanical properties of wire-arc additively manufactured Al-Cu alloy

Wire-arc additive manufacture(WAAM)has great potential for manufacturing of Al-Cu components.However,inferior mechanical properties of WAAM deposited material restrict its industrial application.Inter-layer cold rolling and thermo-mechanical heat treatment(T8)with pre-stretching deformation between solution and aging treatment were adopted in this study.Their effects on hardness,mechanical properties and microstructure were analyzed and compared to the conventional heat treatment(T6).The results show that cold rolling increases the hardness and strengths,which further increase with T8 treatment.The ultimate tensile strength(UTS)of 513 MPa and yield stress(YS)of 413 MPa can be obtained in the inter-layer cold-rolled sample with T8 treatment,which is much higher than that in the as-deposited samples.The cold-rolled samples show higher elongation than that of as-deposited ones due to significant elimination of porosity in cold rolling;while both the T6 and T8 treatments decrease the elongation.The cold rolling and pre-stretching deformation both contribute to the formation of dense and dispersive precipitatedθ′phases,which inhibits the dislocation movement and enhances the strengths;as a result,T8 treatment shows better strengthening effect than the T6 treatment.The strengthening mechanism was analyzed and it was mainly related to work hardening and precipitation strengthening.

Microstructure and mechanical properties of AZ61 magnesium alloy prepared by repetitive upsetting-extrusion

The process of repetitive upsetting-extrusion （RUE） was used to achieve severe plastic deformation （SPD） for an as-cast AZ61 magnesium alloy in temperature range of 285-380 ℃. The microstructure and mechanical properties of the as-cast and RUE processed AZ61 alloys were investigated. The results indicated that homogeneous fine-grained structure with mean grain size of 3.5 μm was obtained as the accumulated true strain in the axial direction increased to 4.28 after three RUE passes at 285 ℃. The dominant reason of grain refinement was considered the dynamic recrystallization induced by strain localization. It was also found that the microstructural evolution was affected by temperature and accumulated deformation. The mechanical properties of RUE processed AZ61 alloys were significantly improved owing to grain refinement. Furthermore, the relationship between deformation parameters and mechanical properties of AZ61 alloy prepared by RUE processing was revealed by tensile tests carried out at room temperature.

Effect of pre-deformation on aging creep of Al-Li-S4 alloy and its constitutive modeling

A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical properties and microstructures were determined under basic thermodynamics conditions of aging forming. The results show that pre-deformation shortens the time of primary creep and raises the second steady-state creep rate. Then, the total creep strain is greater, but in the range of test parameters it is still smaller than that without pre-deformation. In addition, transmission electron microscopy（TEM） observation shows that pre-deformation promotes the formation of T1 phase and θ′ phase and makes them distribute more dispersively, while inhibits the generation of δ′ phase, which leads to the improvement of mechanical properties of the alloy. A unified constitutive model reflecting the effects of aging mechanism, stress levels and different pre-deformations was established. The fitting results agree with the experimental data well.

Effects of alloying and deformation on microstructures and properties of Cu-Mg-Te-Y alloys

New copper alloys with high mechanical properties and high electrical conductivity were prepared, and the effects of addition of minor Mg and Y elements on microstructures and properties were studied. The high tensile strength of above 510 MPa, high elongation of 11%and high electrical conductivity of over 63%IACS can be simultaneously obtained in Cu-0.47Mg-0.20Te-0.04Y alloy after deforming and annealing treatment. Effects of purification together with the grain refining by Y and solid-solution strengthening by Mg are appropriate for enhancing mechanical properties and electrical conductivity of the copper alloys.

Effect of thermo-mechanical treatment process on microstructure and mechanical properties of 2A97 Al-Li alloy

2A97 Al-Li alloy was processed by thermo-mechanical treatment at different pre-stretch deformations of 0, 3% and 6%. The microstrucatre observation results reveal that some δ＇ and T1 precipitates are found in a（Al） matrix of 2A97 alloy processed by the heat treatment with no pre-stretch deformation. When the pre-stretch deformation is 3% and 6%, respectively, amounts of tiny T1 and a few of S＇ precipitates precipitates are observed in the microstructures of 2A97 alloy. The tensile test results show that the tensile properties of 2A97 alloys are improved via thermo-mechanical treatment. When the pre-stretch deformation is from 0, 3% to 6%, the ultimate tensile strength values of the 2A97 alloys increase gradually from 447.7, 516.5 to 534.3 MPa, and the elongations decrease from 17.6%, 12.8% to 10.2%, respectively. Moreover, with increasing pre-stretch deformation amount from 0 to 6%, the in-plane anisotropy value of 2A97 alloys becomes more obvious.

Effects of T9I6 thermo-mechanical process on microstructure, mechanical properties and ballistic resistance of 2519A aluminum alloy

The effects of T916 thermo-mechanical process on microstructures, mechanical properties and ballistic resistance of 2519A aluminum alloy were investigated by optical microscopy （OM）, transmission electron microscopy （TEM）, tensile tests and ballistic resistance test. After T916 treatment, the yield strength, tensile strength and elongation rate of 2519A aluminum alloy reach 501 MPa, 540 MPa and 14%, respectively. And the ballistic limit velocity of 2519A-T916 alloy （30 mm in thickness） is 715 rn/s. The microstructure varies near the sidewalls of crater. The interrupted ageing contributes to these excellent properties of the alloy. During T916 process, the precipitation of Guinier Preston （GP） zone is finer and denser during the interrupted ageing, thus resulting in well precipitated strengthening phase.

Microstructure characterization of Ti-6Al-4V titanium laser weld and its deformation

Slip deformation in Ti-6Al-4V titanium laser welds was observed. Laser welding was used to prepare the titanium welds. Macrostructure, microstructure, mechanical property and structure of laser welds were studied using optical microscope, scanning electron microscope, compression experiment, transmission electron microscope （TEM） and high resolution TEM. Subsequently, slip deformation mechanism occurred in fracture and etched weld was discussed. The results indicate that the maximum compression strength reaches 1.191 GPa. Slip deformation easily happens in titanium laser welds and the minimum slip bands are 600 nm and 75 nm respectively in fracture and etched laser welds.

Influence of pre-deformation on age-hardening response and mechanical properties of extruded Mg-6%Zn-1%Mn alloy

The effect of cold plastic deformation between solution treatment and artificial aging on the age-hardening response and mechanical properties of alloy was investigated by micro-hardness test,tensile test,optical microscopy（OM） and TEM observation.After solution treatment at 420 ℃ for 1 h,three kinds of pre-deformation strains,i.e.0,5% and 10%,were applied to extruded ZM61 bars.Age-hardening curves show that pre-deformation can significantly accelerate the precipitation kinetics and increase peak-hardness value;however,as pre-deformation strain rises from 5% to 10%,there is no gain in peak hardness value.The room temperature（RT） tensile properties demonstrate that increasing the pre-deformation degree can enhance the yield strength（YS） and ultimate tensile strength（UTS） but moderately reduce elongation（EL）;furthermore,the enhancement of YS is larger than that of UTS.No twin can be observed in 5% pre-deformed microstructure;however,a large number of twins are activated after 10% pre-deformation.The peak-aged TEM microstructure shows that pre-deformation can increase the number density of rod-shaped β 1 ＇ precipitates which play a key role in strengthening ZM61 alloy.

Mechanical properties and pore structure deformation behaviour of biomedical porous titanium

Porous titanium has been shown to exhibit desirable properties as biomedical materials. In view of the load-bearing situation, the mechanical properties and pore structure deformation behaviour of porous titanium were studied. Porous titanium with porosities varying from 36%-66% and average pore size of 230 μm was fabricated by powder sintering. Microstructural features were characterized using scanning electron microscopy. Uniaxial compression tests were used to probe the mechanical response in terms of elastic modulus and compressive strength. The mechanical properties of porous titanium were found to be close to the those of human bone, with stiffness values ranging from 1.86 to 14.7 GPa and compressive strength values of 85.16-461.94 MPa. The relationships between mechanical properties and relative densities were established, and the increase in relative density showed significant effects on mechanical properties and deformations of porous titanium. In a lower relative density, the microscopic deformation mechanism of porous titanium was yielding, bending and buckling of cell walls, while the deformation of yielding and bending of cell walls was observed in the porous titanium with higher relative density.

Effects of technical parameters of continuous semisolid rolling on microstructure and mechanical properties of Mg-3Sn-1Mn alloy

A sloping semisolid rheo-rolling process of Mg-3Sn-1Mn alloy was developed, and the effects of process parameters on the microstructure and mechanical properties of Mg-3Sn-lMn alloy strip were studied. The results show that the primary grain average diameter of the strip increases with the increase of the roll speed. The primary grain average diameter decreases firstly and then increases with the increase of the vibration frequency, and the tensile strength and elongation of the strip increase firstly and then decrease with the increase of the vibration frequency. The primary grain average diameter increases with the increase of casting temperature, and the tensile strength and elongation of the strip decrease correspondingly. When the casting temperature is 670℃, the roll speed is 52 mm/s, and the vibration frequency is 60 Hz, Mg-3Sn-1Mn alloy strip with good properties is produced. The mechanical properties of the present product are higher than those of Mg-3Sn-lMn alloy casting with the addition of 0.87% Ce （mass fraction）.

Mechanical properties and microstructures of Al alloy tensile samples produced by serpentine channel pouring rheo-diecasting process

An innovative one-step semi-solid processing technique of A356 Al alloy,the serpentine channel pouring rheo-diecasting process （SCRC）,was explored.The mechanical properties and microstructures of the tensile samples made by the SCRC technique were tested in the as-cast and T6 heat treatment conditions.The experimental results show that the as-cast ultimate tensile strength can reach about 250MPa and the elongation is 8.6%？13.2%.The ultimate tensile strength can increase approximately 30% higher than that of the as-cast one but there is some slight sacrifice of the plasticity after T6 heat treatment.Under these experimental conditions,the semi-solid A356 Al alloy slurry with primary α1（Al） grains,which have the shape factor of 0.78？0.89 and the grain diameter of 35？45μm,can be prepared by the serpentine channel pouring process.The primary α2（Al） grains are very fine during the secondary solidification stage.Compared with the conventional HPDC process,the SCRC process can improve the microstructures and mechanical properties of the tensile test samples.The advantages of the SCRC process include easily incorporating with an existing HPDC machine,cancelling the preservation and transportation process of the semi-solid alloy slurry,and a higher cost performance.

Mechanical properties of Mg-6Gd-1Y-0.5Zr alloy processed by low temperature thermo-mechanical treatment

An as-solution treated Mg-6Gd-1Y-0.4Zr alloy was processed by low temperature thermo-mechanical treatments （LT-TMT）, including cold tension with various strains followed by aging at 200 °C to peak hardness. The results show that the precipitation kinetics of the alloy experienced LT-TMT is greatly accelerated and the aging time to peak hardness is greatly decreased with increasing tensile strain. The tensile yield strength, ultimate tensile strength and elongation at room temperature of the alloy after cold tension with strain of 10% and peak aging at 200 °C are 251 MPa, 296 MPa and 8%, respectively, which are superior to the commercial heat-resistant WE54 alloy, although the latter has a higher rare earth element content.

Variation of the second-phase morphology and its influence on fracture behavior of Al-Si alloy

Using an optical microscope and scanning electron microscope (SEM), the variation of eutectic Si morphology of Al-Si alloy in solution treatment was observed to study its influence on mechanical properties and fracture behavior. The results show that eutectic Si undergoes stubbing, necking, fragmentation, and growth in the initial stage (250 min); in the middle solution stage (250 to 400 min), the eutectic Si morphology has no significant change, only the degree of spheroidizing becomes higher; after 600 min, the growth of eutectic Si is a coarsening process controlled by diffusion and follows the Liftshitz-Slyozov-Wangner (LSW) model, and the eutectic Si morphology deteriorates due to the occurrence of facets and lap. Based on the quantitative measure and regression analysis, the eutectic Si morphology has a remarkable influence on mechanical properties and fracture behavior.

Si phase morphology and mechanical properties of ZL107 Al alloy improved by La modification and heat treatment

The phase morphology evolution during the solid solution treatment and then artificial aging of the La-modified ZL107 Al alloy was studied. The results show that when the solid solution was held at 560 ℃ for 6 h, only partial Si phase dissolved into the matrix; however, the precipitation also occurred during the artificial aging process. The precipitation process in Al-Si alloys with or without La-modification was compared. After modification and heat treatment, the mechanical properties of the alloy were greatly enhanced, due to the modification and uniform distribution of Si phase.

Microstructure evolution and mechanical properties of ZK60 magnesium alloy produced by SSTT and RAP route in semi-solid state

The microstructure evolution and mechanical properties of a ZK60 magnesium alloy produced by the semi-solid thermal transformation （SSTT） route and the recrystallization and partial melting （RAP） route were studied, respectively. The microstructure evolution during partial remelting was studied at different temperatures for different time. The tensile mechanical properties of thixoformed components by the two routes at room temperature were examined. The results show that coalescence is dominant in the SSTT alloy and Ostwald ripening is dominant in the RAP alloy. Compared with the SSTT route, the RAP route can produce finer semi-solid microstructure under the similar isothermal holding condition. The microstructure of the RAP alloy is much more spheroidized compared with the SSTT alloy. Thixoforming for the ZK60 magnesium alloy produced by the SSTT and RAP route results in successful filling of the die, and the thixoforming process improves the mechanical properties of ZK60 magnesium alloy. The RAP alloy shows significantly advantageous mechanical properties over that of the SSTT alloy.

Quantitative contributions of solution atoms, precipitates and deformation to microstructures and properties of Al-Sc-Zr alloys

In order to investigate the effects of solid solution atoms, precipitated particles and cold deformation on the microstructures and properties of Al-Sc-Zr alloys, the Al-Sc-Zr alloys prepared by continuous rheo-extrusion were treated by thermomechanical treatment, analyzed for conductivity and mechanical properties by tensile and microhardness testing, and characterized using optical microscope, TEM and STEM. A mathematical model was established to quantitatively characterize the contribution of solid solution atoms, precipitates and cold deformation to the conductivity of the alloy. The results show that the strength of Al alloy can be significantly improved by solid solution, aging and cold deformation, and the quantitative impacts of solution atoms, precipitates and cold deformation on the conductivity of Al alloy are 10.5%(IACS), 2.3%(IACS) and 0.5%(IACS), respectively. Aging and cold deformation treatments are the keys to obtain high-strength and high-conductivity aluminum alloy wires.

Plastic deformation behavior of Mg97Zn1Y2 extruded alloys

The mechanical properties of the Mg97ZnlY2 extruded alloy containing the long-period stacking ordered phase, the so-called LPSO-phase, with a volume fraction of 24%-25%, were examined by compression tests and cyclic tension-compression deformation tests. The plastic behavior of the extruded alloys with compositions of Mg99.2Zn0.2Y0.6 and Mg89Zn4Y7 （molar fraction, %）, which were almost the same compositions of Mg matrix phase and LPSO phase in Mg97Zn1Y2 Mg/LPSO two-phase alloy, respectively, were also prepared. By comparing their mechanical properties, the strengthening mechanisms operating in the Mg97Zn1 Y2 extruded alloy were discussed. Existence of the LPSO-phase strongly enhanced the refinement of Mg matrix grain size during extrusion, which led to a large increment of the strength of alloy. In addition, the LPSO-phases, which were aligned along the extrusion direction in Mg97Zn1Y2 extruded alloy, acted as hardening phases, just like reinforced fibers.

Relationship among microstructure,mechanical properties and texture of TA32 titanium alloy sheets during hot tensile deformation

The relationship among microstructure,mechanical properties and texture of TA32 titanium alloy sheets during hot tensile deformation at 800℃was investigated.In the test,the original sheet exhibited relatively low flow stress and sound plasticity,and increasing the heat treatment temperature resulted in an increased ultimate tensile strength(UTS)and a decreased elongation(EL).The deformation mechanism of TA32 alloy was dominated by high angle grain boundaries sliding and coordinated by dislocation motion.The coarsening of grains and the annihilation of dislocations in heat-treated specimens weakened the deformation ability of material,which led to the increase in flow stress.Based on the high-temperature creep equation,the quantitative relationship between microstructure and flow stress was established.The grain size exponent andαphase strength constant of TA32 alloy were calculated to be 1.57 and 549.58 MPa,respectively.The flow stress was accurately predicted by combining with the corresponding phase volume fraction and grain size.Besides,the deformation behavior of TA32 alloy was also dependent on the orientation of predominantαphase,and the main slip mode was the activation of prismaticslip system.The decrease of near prism-oriented texture in heat-treated specimens resulted in the enhancement of strength of the material.