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.

Thermodynamic analysis of the compositional control of inclusions in cutting-wire steel

Data from a thermodynamic database and the calculation software FactSage were used to investigate the phase diagrams of the MnO？CaO？SiO2？Al2O3 system in cutting-wire steel and the effects of oxide components on the low-melting-point （LMP） zone in the cor-responding phase diagrams. Furthermore, the activities of oxide components in the quaternary system at an Al2O3 content of 25wt%were calculated. The contents of dissolved [Al] and [O] in liquid steel in equilibrium with LMP inclusions in the MnO-CaO-SiO2-Al2O3 system were optimized. The results show that the MnO-CaO-SiO2-Al2O3 system possesses the largest LMP zone （below 1400℃） at an Al2O3 content of 25wt%and that the CaO content should be simultaneously controlled in the range of 40wt%to 45wt%. The activities of the oxide components CaO, MnO, and SiO2 should be restricted in the ranges of 0 to 0.05, 0.01 to 0.6, and 0.001 to 0.8, respectively. To obtain LMP inclusions, the [Al] and [O] contents in cutting-wire steel must be controlled within the ranges of 0.5 ×10^-6 to 1.0 ×10^-5 and 3.0 ×10^-6 to 5.0 × 10^-5, respectively.

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.

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.

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.

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.

基于U-Net的启闭机钢丝绳缺陷定位方法研究

启闭机钢丝绳在水电站运行中用于闸门提升,对水电生产的安全稳定至关重要。然而,传统的人工检测方法存在效率低、准确率差等问题。利用钢丝绳监测图像进行缺陷定位,不仅可以大幅提高检测效率,还能够实现高准确率的缺陷定位。提出了一种基于U-Net结构的方法,通过编码器提取不同尺度的图像特征,再利用解码器将这些特征还原为缺陷定位标签,从而实现钢丝绳的缺陷定位。实验结果表明,所提方法明显优于传统卷积网络,且在Dice系数、交并比(IoU)和Hausdorff距离3个评价指标上分别优于对比算法0.29、0.23以及0.0047,能够实现更准确的钢丝绳缺陷定位。

Improvement of Inner Quality of High Carbon Wire Rod Steel Using Combined Electromagnetic Stirring

To improve the quality of high carbon wire rods,combined electromagnetic stirring was introduced in the continuous casting of round billets with a diameter of 250mm at Tianjin Rockcheck Steel Group Co.In this paper,the positioning of final electromagnetic stirring(F-EMS)was determined by nail-shooting method.Furthermore,the effect of mold electromagnetic stirring(M-EMS)on the macrostructure and internal defects in the round billets was investigated to find out the optimal operating parameters for continuous casting of SWRH 82B round billets.The results show the desirable positioning of F-EMS locates 9.7m below the mold level where the molten steel can be effectively driven by electromagnetic force and disperse central composition segregation.The shrinkage cavity is totally eliminated with the rotational M-EMS.The ratio and index of central composition segregation and center porosity can be reduced significantly. Furthermore,the equiaxed crystal ratio is considerably increased to 64%under 480A/3Hz M-EMS and 500A/10Hz F-EMS. Fine microstructure and mechanical property of wire rod are presented after optimization of combined electromagnetic stirring.Accordingly,the probability of occurrence of cup-cone fracture of wire rod is reduced dramatically.

线棒材和H型钢产品的缺陷组织

选取线棒材HRB400E钢、45钢、Q355B钢中的不合格试样,对其中贝氏体、网状铁素体、魏氏组织、带状组织等缺陷组织产生的原因进行分析。结果表明:采用调整钢材加热温度、出精轧温度、轧后冷却速率等工艺参数的方法,可以避免材料产生缺陷组织。研究结果可为提高钢材产品的合格率提供支持。

盘扣式钢管脚手架施工技术研究

研究主要分析了盘扣式外架与定型化金属网片组合使用的应用现场。针对传统钢管脚手架与密目式安全网组合方法存在的弊端进行探究,研究结合具体项目的实际情况,采用了这种新的组合方法,做出了新的临时拉结与卸荷方式,达到了提高效率,保证质量,提升外立面形象,减少风险的目的,研究旨在为同类工程提供借鉴经验。

钢丝网高强混凝土抗爆性能试验研究

在同等条件下,用0.6 kg和1.8 kg的TNT药块对体积含量2.15%的钢丝网增强高强混凝土(HSC)试件和体积含量3%和5%的钢纤维增强HSC试件进行接触爆炸试验,并将试验结果进行比较。结果表明,体积含量2.15%的钢丝网增强HSC试件抗爆性能介于体积含量3%、5%的钢纤维增强HSC试件之间,抗爆性能具有优势,但优势略逊于抗侵彻性能。基于试验结果的综合分析,利用钢丝网HSC进行防护工程的抗爆结构设计时,其ka值可取为0.054.

含钢丝网遮弹层的结构靶的力学性能与枪弹射击试验研究

综述了国内外抗侵彻材料的研究现状 ,并借鉴前人研究复合遮弹层的技术和经验 ,提出了一种新型材料———钢丝网遮弹层 ,并以不同的基体材料和不同的钢丝网含量制作多种结构的试件 ,对它们进行了步枪弹射击试验和抗弯、抗压、抗冲击等静动态试验研究 ,并与钢纤维水泥砂浆做性能对比。试验表明 ,钢丝网的使用能显著改善基体材料的抗侵彻性能和静动态力学性能 ;钢丝网水泥细砂浆可作为遮弹层的优选材料且在工艺允许的范围内 ,随钢丝网的层数增加 。

混凝土复合材料的静态试验研究

随着钻地武器的发展,现有防护工程材料受到严峻挑战,其发展的状况是我国打赢现代高技术战争的十分重要的决定因素.设计出一种新型防护工程材料——钢丝网混凝土,并与几种防护工程的常用复合材料进行静态抗弯、抗压、抗劈拉强度对比.试验证明,钢丝网混凝土的静态力学性能最优,是一种具有良好应用前景的防护复合材料.

钢丝网增强特种混凝土的静动态试验研究

在高技术战争条件下,随着钻地武器的发展,现有防护工程材料受到严峻挑战,其发展状况是我国打赢现代高技术战争的十分重要的决定因素。研制高性能防护工程材料成为我国的一个重大事项。在了解国内外已用或在研的防护复合材料的基础上,本文研究设计出一种新型防护工程复合材料钢丝网增强特种混凝土。以特种组分和配比的混凝土及纯水泥浆为基体材料,钢丝网、钢纤维为增强材料,设计出17种不同构造结构的复合材料。对这些材料的构件进行了大量静动态对比试验研究。试验结果说明,钢丝网增强特种混凝土构件具有最高的抗弯、抗压、抗劈拉强度,并且效费比最高,是一种具有良好应用前景的防护复合材料。

钢丝网-钢纤维增强活性粉末混凝土力学性能试验研究

研究钢丝网、钢纤维对活性粉末混凝土(RPC)的增强作用。对所设计的不同钢纤维掺量的钢丝网—钢纤维增强RPC试件,测试分析其抗弯、抗压、劈裂抗拉和抗冲击强度。试验结果表明:在钢丝网中加入钢纤维可以有效的提高钢丝网RPC的各项力学性能指标;钢丝网—钢纤维增强RPC中钢纤维的最佳掺量体积比例为2%.