Effect of fretting amplitudes on fretting wear behavior of steel wires in coal mines

Given that fretting wear causes failure in steel wires, we carried out tangential fretting wear tests of steel wires on a self-made fretting wear test rig under contact loads of 9 and 29 N and fretting amplitudes ranging from 5 to 180 μm. We observed morphologies of fretted steel wire surfaces on an S-3000N scanning electron microscope in order to analyze fretting wear mecha-nisms. The results show that the fretting regime of steel wires transforms from partial slip regime into mixed fretting regime and gross slip regime with an increase in fretting amplitudes under a given contact load. In partial slip regime, the friction coefficient has a relatively low value. Four stages can be defined in mixed fretting and gross slip regimes. The fretting wear of steel wires in-creases obviously with increases in fretting amplitudes. Fretting scars present a typical morphology of annularity, showing slight damage in partial slip regime. However, wear clearly increases in mixed fretting regime where wear mechanism is a combination of plastic deformation, abrasive wear and oxidative wear. In gross slip regime, more severe degradation is present than in the other regimes. The main fretting wear mechanisms of steel wires are abrasive wear, surface fatigue and friction oxidation.

A STUDY OF CONTINUOUS EXTRUSION-CLADDING PROCESSFOR PRODUCTION OF ALUMINUM-CLADDING STEEL WIRE

In this study the process of cladding steel wires with aluminum is investigated experimentally. It is studied how the cladding process and the quality of products are influenced by the aluminum deformation temperature, the wheel speed, the temperature of steel wire, the wire speed and the steel wire tensile force. The relation among the process parameters above is discussed, and the effect of the aluminum deformation temperature on the coating microstructure is analyzed. This paper suggested a reasonable range of process parameters for producing aluminum cladding steel wires.

Electrochemical corrosion behavior of steel wires in a coalmine with a corrosive medium

A6×19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory,simulating the actual working conditions in a coalmine.An electrochemical method was used to investigate the corrosion behavior of steel wires with different surface treatments of a corrosive acid solution.The results show that anode activation of steel wire mainly occurs during pre-corrosion,where the anode activation process of bare steel wires is the fastest as is their corresponding corrosion speed,while the anode activation process of oil coated steel wires and their corresponding corrosion speed are the lowest.During the intermediate and late immersion periods, a passive film is generated on the surface of steel wires,which are gradually damaged with the passage of time.Local pitting corrosion occurs easily on the surface of steel wires with a high-polarization potential. Suitable equivalent circuits were chosen to fit the electrochemical impedance spectroscopy（EIS）of steel wires over various corrosive times and different surface treatments,which indicate good fitting results. The double electrical layer charge-transfer resistance increases in the sequence：bare steel wire, untreated steel wire and oil coated steel wire and their corrosion resistance decreases in turn,which is consistent with their polarization curves.The oil layer provides a certain protective effect on untreated steel wires,but its effect is not entirely clear.

DEFORMATION AND STRENGTHENING OF COLD-DRAWN STEEL WIRES

It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high density of dislocations emerges at the Fe_3C/Fe interface. Furthermore,there are some evidences to support that dislocation cuts through Fe_3C.There- fore,it is necessary to consider the contribution of cementite being sheared strengthening.

DRAWING OF ALUMINUM-CLAD STEEL WIRE BY FORCE-FEED LUBRICATION

The force feed lubrication method is used for drawing aluminum clad steel wire. It is studied how deformation of wire and aspect of the lubricant film are influenced by the die angle, the reduction, the drawing speed and the gap between pressure die and wire. It has been concluded that when the factors above mentioned promote to thicken lubricant film, the drawing force is reduced and this favors the homogenous deformation of aluminum coating and steel core.

Characteristic of Near-surface Microstructure and Its Effects on the Torsion Performance of Cold Drawn Pearlitic Steel Wires for Bridge Cables

The characteristic of near-surface microstructure and its effects on the torsion performance of cold-drawn pearlitic steel wires for bridge cables were investigated by focused ion beam-scanning electron microscope,transmission electron microscopy and differential scanning calorimetry.The samples with similar tensile strength before and after hot-dip galvanizing process are,respectively,characterized as delaminated and non-delaminated in torsion test which indicates that the tensile strength is independent of the toughness value(i e,reduction area and torsion ability).It is interesting to find that there exists submicron granular ferrite on near-surface of the wires,which can be attributed to dislocation rearrangement and sub-grains rotation during cold drawing and hot-dip galvanizing process.And their distribution can suggest homogeneousness of deformation degree to a certain extent:the closer to the surface of their distribution,the more homogeneous deformation of the wires.There is a close relationship between the thermal stability of the cementite layer and distribution of granular ferrite:differential scanning calorimetry(DSC)analysis shows that the sample is accompanied by submicron granular ferrite which is located closer to the surface has higher thermal stability under galvanizing temperature(450°C).A new mechanism of the torsion delamination of pearlitic steel wires is discussed in terms of the thermal stability of the cementite layer and distribution of granular ferrite.

Present situation and countermeasure of low-alloy spring steel wire rod for domestic automobile

The variety,inner quality and surface quality of low-alloy spring steel wire rod for domestic automobile is summarized in detail.And according to commercial low-alloy spring steel wire rod variety, product quality level and its actual application situation on automobile supplied by present industrially developed country metallurgy enterprises,it is pointed that the variety of low-alloy spring steel wire rod for domestic automobile can't satisfy the requirements of automobile industry development,compare with overseas advanced technology,product quality has the following gaps:the first is that steel purity is low,the control level of non-metallic inclusions is not steady,there is often large grain difficult deforming non-deformation inclusions existing,the control level of steel purity has big difference,the level of large steel factory is high,but its steady has a large gap compare with foreign advanced level,not to mention small steel factory which research and development powder is low.The second is surface complete decarburization can' t be avoided completely.The third is that surface defects are more.The fourth is that composition segregation and structure segregation are not steady,steel wire can't be drawn normally when the segregation is serious. In all,the segregation of 55SiCrA is superior to 60Si2MnA obviously.The industrialization of domestic high level low-alloy spring steel wire rod can't seek quick success and instant benefits,independent innovation perseveringly must be adopted,the success may be reached after master core technologies and adopt the science way of step by step.

Fretting wear of steel wires in hoisting ropes

To investigate the fretting wear of steel wires in hoisting ropes, specimenswere made of 6X19 point contact ropes. A model for the fretting ear was developed and a frettingwear test rig was deigned in laboratory. A series of experiments were performed on this test rig.The wear volume was taken as a characteristic parameter to describe the fretting wear in relation tothe contact load, reciprocating cycles and amplitude. Moreover, the wear mechanisms were discussedin the fretting process.

Synthesis and Characterization of ZnO Film on Stainless Steel Wire and Bioaerosol Antimicrobial Activity Evaluation

ZnO thin films were prepared by electrophoretic deposition on stainless steel wire sieve, using zinc acetate as a precursor. The film was sintered and characterised by Scanning Electron Microscopy （SEM）, X-Ray Diffraction （XRD） and chemisorption of oxygen. A culture bacterial consortium composed by gram negative rod-shaped microbes was prepared in a liquid agar in a flask. It was transported by air through a reactor equipped with a UV lamp with 3 and 5 sieves of a stainless steel wire coated with ZnO film. It was exposed in continuous in five experiments to photocatalytic advanced oxidation. The experiments showed a total efficiency for colony forming unit reduction of a maximum of 99.66% for a residence time of 20 seconds with 5 stainless steel wire where exposed in continuous to UV. Also they were evaluated at 7.5 seconds, observing that the contribution of residence time and amount of catalytic for the CFU reduction was quite similar. Variance analysis showed that the efficiency was significant with the no parametric Kruskal-Wallis test with P 〈 0.05. This technology could be used to clean indoor air of closed environments such as hospitals, crowded buildings or public transportation systems where airborne bacteria has been documented.

Influence of Fatigue Loading on the Residual Stress Distribution in Prestressing Steel Wires

This paper analyzes the influence of fatigue loading on the residual stress profile in high strength steel wires. To this end, different sinusoidal loads with diverse values of maximum loading level and number of cycles were simulated on wires in which several residual stress profiles had been previously introduced, some of them with a tensile state and others with a compressive state. An analysis was made of the evolution with time of such residual stress laws by comparing them at key instants of loading, that is, at initial instant, at maximum load, at minimum load and at final instant. Numerical results show only a minor influence of fatigue loading on the residual stress profile.

Dynamic design of a nonlinear energy sink with NiTiNOL-steel wire ropes based on nonlinear output frequency response functions

A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.

Arc characteristics of submerged arc welding with stainless steel wire

The arc characteristics of submerged arc welding （SAW） with stainless steel wire were studied by using Analysator Hannover （AH）. The tests were carded out under the same preset arc voltage combined with different welding currents. By comparing the probability density distribution （PDD） curves of arc voltage and welding current, the changes were analyzed, the metal transfer mode in SAW was deduced, and the characteristics of a stable arc were summarized. The analysis results show that, with an increase of welding parameters, the short-circuiting peak in the PDD curves of arc voltage decreases gradually until it disappears, and the dominant metal transfer mode changes from flux-wall guided transfer to projected transfer and then to streaming transfer. Moreover, when the PDD curves of arc voltage are both unimodal and generally symmetrical, the greater the peak probability and the smaller the peak span, the more stable the arc becomes.

Study on rolling process optimization of high carbon steel wire

The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.

Experimental Study on the Mechanical Properties of FRP Bars by Hybridizing with Steel Wires

Many studies on fiber reinforced polymer composite bars, as a substitute for reinforcing bars, have been conducted to solve corrosion of steel in reinforced concrete structures since 1960s’. However, FRP Bars have a lower elastic modulus than steel rebar as a structural component of concrete structures. Material properties with brittleness fracture and low elastic modulus can be improved by combining cheaper steel than carbon or aramid fibers. In this study, prototypes of FRP Bars with inserted steel wires (i.e., “FRP Hybrid Bars”) were developed and their tensile performance was compared depending on the proportion and diameter of steel. The FRP Hybrid Bars were made by dividing them into D13 and D16 according to the diameter and proportion of inserted wires: GFRPs were combined with wires having different diameters of 0.5 mm, 1.0 mm, and 2.0 mm in the proportion of 10%, 30%, 50%, and 70%, respectively. As a result of tensile tests, the elastic modulus of FRP Hybrid Bars were improved as 20% - 190% in comparison with the fully GFRP Bars.

Principles of X-Ray Non-Destructive Testing for Steel Wire Ropes in Conveyer Belt

The principles of X-ray Non-destructive testing (NDT) for steel wire ropes buried in conveyer belt is described in the paper. The mathematical model for calculating the effective cross section of wire ropes has been developed. The test data on steel wire rope samples of various types are presented,which have been compared with the National Standard. And this calculation model for the effective cross section is very important to the prediction system for transverse failure of conveyer belt.

The Inspection of Spheroidized Annealing on SCM435 Cold-Forging Quality Steel Wires with Protective Atmosphere

A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.

Friction and wear of multiple steel wires in a wire rope

The fretting wear among the steel wires aggravates the wire rope’s fatigue damage,affects the service performance of the wire ropes,and threatens mine hoisting safety.In this paper,the practical friction behavior and wear mechanism among the wires in the wire rope are investigated.A series of tests were carried out on multiple steel wires in helical contact and tension–torsion coupling under different fretting parameters,twisting parameters,and lubrication conditions by self-made friction and wear testing machine.The results show that the coefficient of friction(COF)among the steel wires decreases slightly with increasing lateral loads and tension,and the effect of twist angle on the COF has opposite results under different lubrication conditions.Lateral loads,tension of the steel wires,twist angle,and lubrication condition all affect the fretting morphology among the steel wires.Fretting wear with larger twist angle structure leads to more energy loss.The energy loss of fretting is directly related to the fretting morphology among the contact surfaces,and the dissipated energy is lower in the two forms of complete slip and sticking.The wear depth and width increase with the increase of lateral loads,steel wire tension,and twist angle.And the wear width and depth under dry friction conditions are higher than those under oil lubrication conditions.In addition,the wear mechanism under dry friction conditions is mainly abrasive wear,adhesive wear,and fatigue wear.And the wear mechanism under oil lubrication conditions is mainly abrasive wear and fatigue wear.

Tribo-corrosion interaction of the parallel steel wires in the suspension bridges

The effect of contact load and relative displacement on tribo-corrosion interaction of parallel steel wires of main cable in the suspension bridge was investigated in this study.A self-made tribo-corrosion test bench was employed to conduct tribo-corrosion tests of parallel steel wires in 3.5%(wt%)NaCl solution and deionized water under different contact loads and different relative displacements.The friction coefficient and wear coefficient of wires were presented.Electrochemical corrosion behavior(Tafel polarization curves,Nyquist diagram,and equivalent circuit diagram)was characterized by electrochemical analyzer.Wear morphology was observed by scanning electron microscope.Wear volume loss and corrosion‒wear interaction were quantitatively demonstrated by high-precision weighing balance.The results show that the electrochemical corrosion ability of the steel wires increases with the increase of the contact load or relative displacement.The increased contact load or relative displacement increases the volume loss of corrosion‒wear and pure wear,but decreases the wear coefficient.The wear mechanisms in 3.5%NaCl solution are adhesive wear,abrasive wear,and corrosive wear as compared to adhesive wear and abrasive wear in deionized water under different contact loads.The wear mechanisms of parallel steel wires are slightly different under different relative displacements.But the main wear mechanisms are similar to that under different contact loads.The interaction effects of corrosion and wear produced by the contact load and relative displacement are all the synergistic effects.

Effect of rare earth content on microstructure and corrosion resistance of hot-dip Zn-5Al alloy coated steel wire for bridge cables

The effects of the content of rare earth elements on the microstructure and properties of hot-dip Zn-5 Al alloy steel wire for bridge cables were investigated.The microstructure of the hot-dip coating was analyzed using an optical microscope and a scanning electron microscope equipped with an energy-dispersive spectrometer.The bonding force between the hot-dip coating and steel wire was determined by the winding test.The corrosion resistance of the steel wire hot-dip coating was tested by the electrochemical workstation.The hot-dip Zn-5A1 alloy coating has a corrosion-resistant structure composed of a zinc-rich phase and an aluminum-rich phase.Due to the enhanced bonding force,the micro structure of the hot-dip coating of the Zn-5A1 alloy with rare earth elements is more compact and uniform than that without rare earth elements.The addition of rare earth elements improves the corrosion resistance of Zn-5A1 alloy coated steel wire.Due to the rare earth segregation,which prevents the corrosion of the grain boundary and enhances the anti-intergranular corrosion performance,steel wire exhibits the optimum corrosion resistance when the content of rare earth elements is 0.08 wt.%.

Fracture Characteristics of Fully Pearlitic Steel Wire in Tension and Torsion

The fracture characteristics of fully pearlitic steel wires with fine and randomly oriented lamellae have been investigated after tension and torsion, respectively. It is found that the predominant fracture mode under small pre- deformation is dimple. The analysis of the colony size and the lamellar structure near the fracture surface indicates that each dimple roots from one colony. A simulation of tensile deformation with several pearlitic colonies based on the real scanning electron microscopy （SEM） observation shows that the plastic deformation concentrates and the stress t^hxialit~＂ is larger ~it the boundaries bf colonies. It demonstrates the microe/＇a^ks initialize at colony boundaries. Thus, the colony size is a significant factor for fracture behaviors under small pre-deformation. On the other hand, the fracture surface is investigated after large pre-deformation via torsion. The results show that fracture characteristics vary with radius from dimples, elongated dimples to the fibrous structure. It indicates that the fracture charac-teristics are dependent on the pre-deformation. The fracture mode under large pre-deformation becomes an anisotropic fibrous structure instead of dimples.