Effect of heat treatment on microstructure and mechanical properties of Ti-containing low alloy martensitic wear-resistant steel

Effects of quenching temperature and cooling conditions(water cooling and 10%NaCl cooling)on microstructure and mechanical properties of a 0.2%Ti low alloy martensitic wear-resistant steel used for die casting ejector plate were investigated.The results show that lath martensite can be obtained after austenitizing in the range of 860-980℃and then water cooling.With an increase in austenitizing temperature,the precipitate content gradually decreases.The precipitates are mainly composed of TiC and Ti4C2S2,and their total content is between 1.15wt.%and 1.64wt.%.The precipitate phase concentration by water-cooling is higher than that by10%NaCl cooling due to the lower cooling rate of water cooling.As the austeniting temperature increases,the hardness and tensile strength of both water cooled and 10%NaCl cooled steels firstly increase and then decrease.The experimental steel exhibits the best comprehensive mechanical properties after being austenitized at 900℃,cooled by 10%NaCl,and then tempered at 200℃.Its hardness,ultimate tensile strength,and wear rate reach551.4 HBW,1,438.2 MPa,and 0.48×10^(-2)mg·m^(-1),respectively.

Microstructures and wear-resistant properties of in-situ TiC_p/ZA-12 composites

TiC_p/ZA-12 composites were fabricated by exothermic disposition method process and stirring-casting techniques. The microstructure and wear-resistant properties were investigated . The results show that TiC particles are formed in-situ and distributed uniformly in matrix. No particles aggregation and macro or micro precipitation are observed. The wear-resistant properties of composites increase with the increase of TiC_p content, but will not increase when the TiC_p content reaches constant value. Finally, the friction and wear mechanism were also discussed.

Effects of air-atomized water spray cooling device structure on the quenching process,microstructure,and properties of wear-resistant steel

With its high strength and hardness, wear-resistant steel has become an important material in the field of construction machinery manufacturing.Given that quenching technology is a crucial component of wear-resistant steel production, the selection of the cooling method to be used during this process is important.In this study, the feasibility of quenching wear-resistant steel by air-atomized water spray cooling was studied, and the cooling rate, microstructure, and hardness of wear-resistant steel under various cooling device structures were analyzed.The results reveal that the air-atomized water spray cooling method is an effective technique in quenching wear-resistant steel.Furthermore, martensite and uniform hardness were obtained by the air-atomized water spray cooling technique.As the space between the nozzles in each row in the device increased, the cooling rate was reduced during quenching.Meanwhile, the martensite content decreased, and more carbides were observed in the martensitic structure.A mixture comprising self-tempered martensite and bainite was formed at a large distance over a longer period of time.All these factors resulted in lower hardness and worse property uniformity.

Hot cracking susceptibility research in BTW1 austenitic high-manganese wear-resistant steel

Baosteel’s first BTW1 austenitic high-manganese wear-resistant steel exhibits strong deformation-induced hardening characteristics.Compared with common low-alloy martensitic wear-resistant steels in the market, it has improved impact wear resistance, hard abrasive wear, erosion wear performance, and impact toughness.The metallurgical properties of such austenitic wear-resistant steel lead to the risk of failure because of hot cracking defects in the welded structure.In wear-resistant applications, evaluating hot cracking susceptibility is necessary to avoid the effect of welding defects.In this study, the Varestraint test is used to quantitatively analyze and evaluate the hot cracking susceptibility of BTW1 austenitic high-manganese wear-resistant steel.The test results show that by controlling the content of impurity elements and grain refinement, BTW1 austenitic high-manganese wear-resistant steel effectively reduces hot cracking tendency and has a low incidence of hot cracking under small strain conditions.The developed matching welding process can effectively avoid the influence of hot cracking susceptibility.

Numerical simulation of temperature field in laser-arc hybrid welding of wear-resistant steel

Using ABAQUS software and cylindrical ellipsoid and body heat sources with a peak-heat-flux- attenuation function, a finite element model of the temperature field in the laser-arc hybrid welding of 4.5-mm BW300TP wear-resistant steel is proposed. The proposed model considers convection, radiation, molten pool flow, and heat conduction effect on temperature. A comparison of the simulation and actual welding test results confirms the reliability of the model. This welding heat-process model can provide the cooling rate at any position in the heat affected zone （HAZ） and can be used as a reference for the analysis of material properties and for process optimization.

Developing Maanshan Kuangyou Wear-resistant Materials Group Company

Maanshan KuangyouGroup company is a special largeenterprise making wear-resistantmaterials products,integratingscience,industry and trade.Mainproducts are chromium-contentwear-resistant materials and ship-use anchor chains."Kuangyou"Brand balls have been awardedprizes of Quality Products by theprovince and ministry,and prizeof Scientific Progress by theprovince,and are widely appliedin mining,cement,power andchemicals industries.Ship-useanchor chains have an

Evolution of deformation twins with strain rate in a mediummanganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V

Microstructure evolutions of the medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V (in wt.%) with stacking-fault energy of 22 mJ m-2 during deformation at strain rate ranging of 10^-2-1 s^-1 were analyzed by means of X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the twinning-induced plasticity effect is the main strengthening mechanism of the studied steel, whilst the transformation-induced plasticity effect only occurs at high strain rate. With an increase in strain rate, volume fraction of the deformation twins, in particular that of the secondary twins, increases significantly along with decreasing average size. When applied strain rate is higher than 10^-1 s^-1, the parallel deformation twins are turned into a crossing morphology, and the original straight twin boundaries exhibit a ladder feature, which is attributed to the interactions between regular dislocations and twin dislocations at the twin boundary. The critical strain, a key indicator of the initiation of deformation twin, decreases with increasing strain rate. In addition, the ductility and strength of medium-manganese wear-resistant steel Fe-8Mn-1C-1.2Cr-0.2V are mainly determined by the shape and volume fraction of deformation twins.

Microstructure and properties evolution of Nb-bearing medium Cr wear-resistant cast steel during heat treatment

The effect of quenching temperature and cooling conditions on the microstructure and mechanical properties of a 0.2%Nb medium chromium wear-resistant cast steel was investigated.The microstructure,carbides and volume fraction of retained austenite were characterized using the optical microscope,scanning electron microscope,transmission electron microscope and X-ray diffraction.The influence of heat treatment on hardness,impact toughness and tensile properties of test steel was studied.It can be observed that lath martensite can be obtained under the condition of air cooling and oil cooling upon austenitizing in the range of 900–1020℃.Total carbide content of 0.2–1.1 wt.%under air cooling is more than that under oil cooling due to the lower cooling rate.Nb6C5,M23C6 and M7C3 were found at lower austenitizing temperature,of which niobium carbide mostly located at grain boundaries,while chromium carbides were uniformly distributed in the matrix with the size of 20–50 nm.The chromium carbides are basically dissolved into the matrix in test steel austenitized at 1020°C.Meanwhile,the negligible growth of prior austenite grain size is achieved.Specimen austenitized at 1020℃ and cooled in air+tempered at 200℃ has a best combination of hardness,plasticity and tensile strength due to fine grain size and more amount of retained austenite.Under this condition,the hardness is 58 HRC,the impact toughness is 22.92 J/cm^(2),and the tensile strength is 1136.9 MPa.

Characterization of hot deformation behavior of wear-resistant steel BTWl using processing maps and constitutive equations

In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.

Development and Production of HSLA Wear-Resistant Steel

In this paper,the development and production of Ti-Cr-B microalloyed NM400 wear-resistant steel were discussed,along with the influence of heat treatment process parameters on the mechanical properties.The continuous cooling transformation behavior of steel was investigated by means of thermal simulator.Effects of austenitizing temperature on microstructures and properties of steel were studied.Martensite laths evolution,carbide transformation and precipitation behavior were observed by TEM.The wear-resistance of steel was compared with other similar steels.The results show that the steel has high strength and hardness,great low-temperature toughness and wear-resistance.The tensile strength is more than 1300 MPa,and the hardness is in the range of 390-430 HB.Due to the good hardenability,the steel has a uniform hardness distribution on the surface and thickness direction.The plate shape,cold bending property and weldability of the product can meet the user’s requirement.

Micro-impact testing: A novel nano-/micro-tribological tool for assessing the performance of wear-resistant coatings under impact/fatigue conditions

A novel repetitive contact technique, micro-impact testing, has been developed forcoating evaluation. Impact test results have proved a more consistent measure of coating per-formance under impact/fatigue conditions than traditional tribological methods such as scratch orpin-on-disk testing. The operating principles of the technique are described with some illustrativeresults on hard and soft coatings. The technique can provide information on impact wear resis-tance, susceptibility to brittle fracture, and strength of interfacial adhesion to substrate.

Wear-resisting Oxide Films for 900℃

A study was conducted to develop low-friction, wear-resistant surfaces on high temperature alloys for the temperature range from 26℃ to 900℃. The approach investigated consists of modifying the naturally occurring oxide film in order to improve its tribological properties. Improvement is needed at low temperatures where the oxide film, previously formed at high temperature, spalls due to stresses induced by sliding. Experiments with Ti, W and Ta additions show a beneficial effect when added to Ni and Ni-base alloys. Low friction can be maintained down to 100℃ from 900℃. For unalloyed Ni friction and surface damage increases at 400℃ to 500℃. Two new alloys were perpared based on the beneficial results of binary alloys and ZrO2 diffusion in Ni.Low friction at temperature above 500℃ and reasonable values (0.32~0.42) at low temperature are obtained.

MICROSTRUCTURES OF A NOVEL HIGH STRENGTH AND WEAR-RESISTING ZINC ALLOY

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Elements inter-diffusion in the turning of wear-resistance aluminum bronze

Inter-diffusion of elements between the tool and the workpiece during theturning of aluminum bronze using high-speed steel and cemented carbide tools have been studied. Thetool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turna novel high strength, wear-resistance aluminum bronze without coolant and lubricant. Adhesion ofworkpiece materials was found on all tools' surface. The diffusion couples made of tool materialsand aluminum bronze were prepared to simulate the inter-diffusion during the machining. The resultsobtained from tool wear samples were compared with those obtained from diffusion couples. Stronginter-diffusion between the tool materials and the aluminum bronze was observed in all samples. Itis concluded mat diffusion plays a significant role in the tool wear mechanism.

Effect of Rare Earths-Treated Glass Fiber on Impact Wear-Resistance of Metal-Plastic Multilayer Composites

The friction and wear properties under impact load and dry friction conditions of metal-plastic multilayer composites filled with glass fiber, treated with rare earth elements, were investigated. The worn surfaces were observed and analyzed by scanning electron microscopy (SEM). It shows that applying rare earth elements surface modifier to treat the glass fiber surface can enhance the interfacial adhesion between the glass fiber and polytetrafluoroethylene (PTFE), as well as promote the interface properties of the composites. This helps to form a uniformly distributed and high adhesive transfer film on the counterface and abate the friction between the composite and the counterface. As a result, the wear of composite is greatly reduced. The composite exhibits excellent friction properties and impact wear-resistance.

Wear-resistance Performance of Spray-welding Coating by Plasma Weld-surfacing

Alloy powders including Ni60, WC, CrC, and TiC with different mass ratios were deposited on medium carbon low alloy steel by plasma welding. Through the experiments, the optimal alloy powder reinforcing cutter tool surface properties were discovered. The wear resistance properties were investigated on the impact abrasive wear tester. The experimental results show that in terms of microstructure, there exists the shape of herringbone, spider mesh, broken flower structures in coatings. In addition, fusion area of four specimens surfacing welding layer displays a large number of acicular martensite with a small amount of austenite. The coating mainly consists of Ni-Cr-Fe austenitic phase and the other precipitates. TiC density is smaller, its content is less in alloy powder, in the process of surfacing welding, TiC is melted fully, which is mainly distributed in surface layer and middle layer of hard facing layer. The content of TiC gradually reduces from surface layer of hard facing layer to the fusion area. Compared to TiC, the density of tungsten carbide and chromium carbide is larger, there exist tungsten carbide and chromium carbide particles, which are not completely melted near the fusion area. The micro-hardness presents gradient change from the fusion area to the surface layer of hard facing layer, and the hardness of the middle layer is slightly lower than that of the fusion area, and the hardness increases near the surface layer.

To a forecasting of the wear-resistance of friction units details parameters question

The process of wear process expedient considering as set of special cases wear. For each special case wear were received settlement with reference to some certain conditions of experimental researches realisation, uniting in self SLOP. For successful application deduced dependence at forecasting wear-resistance the mechanism of reduction is developed which allows to distribute deduced dependencies to any conditions of wear process.

The Effects of WC on the Microstructures and Wear Resistance of FeCoCrNiB_(0.2) High Entropy Alloy

To improve the wear resistance of the FeCoCrNiB_(0.2)high entropy alloy(HEA),the FeCoCrNiB_(0.2)(WC_(0))and FeCoCrNiB_(0.2)+20wt%WC(WC_(20))HEA coatings were prepared on Q235 steel by laser cladding(LC).The microstructure,hardness,and tribometer of the HEA coatings were investigated using scanning electron microscopy with spectroscopy(SEM/EDS),X-ray diffraction(XRD),vickers microhardness tester,and pin-on-disc tribometer,respectively.The experimental results show that the WC0HEA coating comprises a simple BCC phase mixed with an M_(2)B phase.Adding 20wt%WC,the WC_(20)HEA coating is composed of a simple BCC phase mixed with the Cr_(23)C_(6)carbide phase.The microstructure of the WC_(20)HEA coating is simple,which consists of equiaxed grain and dendritic.The microhardness also increases from 625.5HV to 806.0HV,and the wear mass loss correspondingly decreases from 30.9 to 14.9 mg.W and C atoms formed by WC dissolution are mainly dissolved in the BCC phase,which leads to the solution strengthening effect.Besides,Cr_(23)C_(6)carbides inhibit the growth of the grains,play the role of fine-grain strengthening,and further improve the hardness and wear resistance of the HEA coating.

Hardox500的焊接工艺研究

耐磨钢板Hardox500,硬度高,塑韧性和焊接性较差,本文对耐磨钢板Hardox500机械力学性能及焊接性进行分析,从焊接方法、焊接材料以及焊接能量参数、焊接程序等方面设计焊接工艺,并根据NB/T47014-2011《承压设备用焊接工艺评定》标准对焊接工艺进行评定,最终获得优化的焊接工艺。

Tribological and flame retardant modification of polyamide-6 composite

A series of wear and flame resistant polyamide 6(PA6)composites were prepared using glass fiber(GF)and talc(T)as reinforcer,polytetrafluoroethylene(PTFE)and graphite(Gr)as solid lubricants,red phosphorus(RP)and zinc borate(ZB)as flame retardant.The tribological property,mechanical property,flame retardant property and the flame retardant mechanism were investigated.The tests show that the formula of the wear resistant PA6 composite(WRPA 6)is PA6/GF/T/PTFE/Gr in the ratio of 100/15/5/10/5 by mass.Because this composite exhibits the lowest friction coefficient(0.1429)and no wear mass loss,the introduction of RP and ZB can increase the flame resistance of WRPA6,and the synergistic effect of RP and ZB is obtained.Detailedly,the composite with 4 parts of ZB and 12 parts of RP shows the best flame retardant property,achieving the highest limiting oxygen index(LOI)(30.2 vol%)and a UL94 V-0 rating,and the flame retardant mechanisms may be gas phase along with condense phase mechanism.