Ti6Al4V的微磨粒磨损研究

研究了医用Ti6Al4V合金在蒸馏水中的微磨粒磨损行为,考察了载荷、滑行距离、料浆浓度和转速对微磨粒磨损规律的影响,并对微磨粒磨损机制进行了讨论。结果表明:随载荷、滑行距离和料浆浓度的增加,Ti6Al4V合金的磨损量增加,磨损机制由三体磨损转变为混合磨损。     

Ti6A14V的微磨粒磨损研究

研究了医用Ti6A14V合金在蒸馏水中的微磨粒磨损行为，考察了载荷、滑行距离、料浆浓度和转速对微磨粒磨损规律的影响，并对微磨粒磨损机制进行了讨论。结果表明：随载荷、滑行距离和料浆浓度的增加，Ti6A14V合金的磨损量增加，磨损机制由三体磨损转变为混合磨损。     

Study of abrasive wear phenomena in dry and slurry 3-body conditions

Machinery and equipment used in abrasive environments, such as the mining industry, suffer from severe wear. In order to understand wear and to prolong the life time of the machinery, it is important to understand how materials respond to wear depending on the environmental and tribological conditions imposed.This paper exposes a comparative study between the influence of two abrasive environments (dry and slurry) on hard particle coatings and steels. To study this, the 3-body wear behaviour was evaluated in a dry environment using a continuous abrasion test (CAT) and in a slurry environment using a slurry steel wheel abrasion test (SSWAT) method. Both tests are capable of experimentally modelling the high stress wear at 45 N and 216 N, using quartz sand as an abrasive. The tests were performed on two types of coatings processed by sintering and hardfacing and martensitic steel was used as a reference. The wear was indicated as volume loss by measuring the samples before and after the tests. Furthermore, the specific wear energy was calculated in order to have a fundamental understanding about the material's response to wear. A correlation between the wear rate and the particle brakeage index (PBI) was done for the dry conditions using different loads, in order to explain the interdependence between the two parameters and the change in the wear mechanism between the two loads. The influence of load on the wear of the materials showed different wear mechanisms on coatings compared to the steel in the same environmental conditions. However, a change in wear mechanism at different load levels was observed, which might be directly dependent on the change of the particle's motion from sliding to rolling combined with the change in their shape and size. The results showed that the need to study the influence of different abrasive conditions on the material wear is crucial in order to improve the lifetime and the cost efficiency of the machinery used in such environments. The hard-particle coatings showed comparatively low wear rates promising a great potential in improving the lifetime of industrial equipments in different environments.     

SUS304亚稳奥氏体不锈钢在耦合摩擦和变形条件下的磨损行为研究

在自制的耦合摩擦和变形的试验机上初步研究了SUS304亚稳奥氏体不锈钢带的磨损变形行为,分析了在耦合摩擦和变形条件下的形变量、磨痕表面的马氏体转变以及磨痕形貌与试验条件的关系。结果表明:研制的试验机实现了SUS304亚稳奥氏体不锈钢带的摩擦和塑性变形的耦合行为;不仅带试样摩擦表面的形貌随正压力增加变化明显,而且其形变量和诱发转变的马氏体量均增大,但马氏体量增加对SUS304奥氏体不锈钢的磨损无明显影响。     

Abrasive wear behaviour of sintered composite austenitic stainless steels having γ-Fe and M23C6 phases

Abstract

Using powder metallurgy, composites of austenitic stainless steel were produced along with unreinforced stainless steel mixed with titanium, cobalt and molybdenum particles. Wear resistance of the materials was measured by a two body pin on disc wear tester. SiC abrasive papers of 80 and 220 mesh sizes were used as abrasive media. Wear tests were performed under loads of 10, 20 and 30 N at room temperature. The abrasive wear measurements showed that the softer, unreinforced austenitic stainless steel exhibited higher mass loss than the composites. Furthermore, the abrasive wear resistance of the reinforced austenitic stainless steel composites increased with increasing FeTi, FeMo, or Co volume content. In addition, the wear rate against the 80 grade SiC abrasive paper increased more than against the 220 grade SiC abrasive paper.     

Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods

The aim of the present study is to evaluate the abrasive wear resistance of some potential abrasion resistant steels exposed to different types of abrasive wear contact conditions typical of mining and transportation applications. The steels investigated, include a ferritic stainless steel, a medium alloyed ferritic carbon steel and a medium alloyed martensitic carbon steel.The abrasive wear resistance of the steels was evaluated using two different laboratory test methods, i.e. pin-on-disc testing and paddle wear testing that expose the materials to sliding abrasion and impact abrasion, respectively. All tests were performed under dry conditions in air at room temperature. In order to evaluate the tribological response of the different steels post-test characterization of the worn surfaces were performed using optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Besides, characterization of the wear induced sub-surface microstructure was performed using optical microscopy.The results show that depending on the abrasive conditions a combination of high hardness and toughness (fracture strain) is of importance in order to obtain a high wear resistance. In the pin-on-disc test (i.e. in sliding abrasion) these properties seem to be controlled by the as-rolled microstructure of the steels although a thin triboinduced sub-surface layer (5–10 μm in thickness) may influence the results. In contrast, in the paddle wear test (i.e. in impact abrasion), resulting in higher forces acting perpendicular to the surface by impacting stones, these properties are definitely controlled by the properties of the active sub-surface layer which also contains small imbedded stone fragments.     

Influence of high-power diode laser heat treatment on wear resistance of a mold steel

The effect of hardness on wear loss and wear behavior during fretting was studied. A high-power diode laser was used to achieve the surface hardening of a mold steel (AISI P20-improved) at temperatures of 1000 and 1200 °C. A hardness increment was detected in laser heat-treated specimens, which may be attributed to phase transformation from ferrite to martensite, influencing wear loss and fretting wear behavior. In the fretting test results, smaller wear scars and less wear loss were observed for laser heat-treated specimens in comparison to those of base metal. Moreover, relatively more stable friction coefficient profiles were obtained for the laser heat-treated specimens due to uniform contact characteristics at two contacting surfaces. The effectiveness of the proposed technique was verified by the morphology of the wear scars of the treated specimens, which had a smooth appearance and minor abrasion grooves.

     

Effect of UHMWPE Microparticles on the Tribological Performances of High-Strength Glass Fabric/Phenolic Laminate Composites Under Water Lubrication

The tribological behaviors of ultra-high molecular weight polyethylene (UHMWPE) microparticle-modified high-strength glass fabric/phenolic laminate composites sliding against stainless steel under water lubrication have been investigated. Results showed that the incorporation of UHMWPE microparticles, especially at the mass fraction of 5.0 %, improved the wear resistance of the laminate composite to a significant extent, because UHMWPE microparticle can effectively absorb and dissipate the friction energy through a plastic deformation during the formation of the regular ripple-like abrasion patterns on its worn surface. During the sliding process, after the phenolic resin was firstly worn off, UHMWPE microparticles with much better wear resistance were protruded from the worn surface of the laminate composite, leading to a fundamental change in the contact status of the matched surfaces from rigid resin and fibers/steel to flexible UHMWPE/steel. As a result, low and steady friction coefficient was obtained due to good adaptability of UHMWPE to water lubrication.     

Effect of Sintering Temperature and Atmosphere on Nonlubricated Sliding Wear of Nano-Yttria-Dispersed and Yttria-Free Duplex and Ferritic Stainless Steel Fabricated by Powder Metallurgy

The nonlubricated sliding wear behavior of nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel against a diamond tip was studied. The stainless steel samples were fabricated by a conventional powder metallurgy route in which nano-yttria-dispersed and yttria-free duplex and ferritic stainless steel powders were cold compacted and then conventionally sintered at either 1000, 1200, or 1400°C in an argon atmosphere. For comparison, another set of samples was sintered at 1000°C in a nitrogen atmosphere. The wear behavior of sintered stainless steel samples against a diamond indenter was investigated using a pin-on-disc apparatus at 10 and 20 N loads and at a constant speed of 0.0041 m/s. It is proposed that yttria-dispersed stainless steels showed higher wear resistance compared to yttria-free stainless steel due to their improved hardness and density. Stainless steel sintered in a nitrogen atmosphere exhibited better wear resistance than those sintered in an argon atmosphere due to the formation of hard and brittle Cr₂N. The wear mechanisms of stainless steels against diamond were found to be mainly abrasive and oxidative. Semiquantitative analysis of the worn surfaces and wear debris confirmed the occurrence of oxidation processes during wear.     

INVESTIGATION OF THE TOOL WEAR AND SURFACE FINISH IN LOW-SPEED MILLING OF STAINLESS STEEL UNDER FLOOD AND MIST LUBRICATION

This paper examines the performance of AlN/TiN coated carbide tool during milling of STAVAX® (modified AISI 420 stainless steel) at a low speed of 50 m/min under conventional flood and mist lubrication. Abrasion, chipping, fracture resulting in the formation of crater and catastrophic failure are the wear mechanisms encountered during machining under flood lubrication. The flank wear, and the likeliness of the cutting tool to fracture, chip and fail prematurely increased with an increase in the hardness of the workpiece and a reduction in the helix angle of the tool. Small quantity of mineral oil sprayed in mist form was effective in reducing the flank wear and severity of abrasion wear, and preventing the formation of crater and the occurrence of catastrophic failure. In milling 35 and 55 HRC-STAVAX® using a feed rate of 0.4 mm/tooth and a depth of cut of 0.2 mm under mist lubrication, the cutting edge of the 25° and 40° helix angle tools only suffered small-scale edge chipping and abrasive wear throughout the entire duration of testing. The influence of the ductility of the workpiece on the surface finish and the effectiveness of mist lubricant in improving the surface finish are also discussed.     

Variations in wear loss with respect to load and sliding speed under dry sand/rubber-wheel abrasion condition: a modeling study

The dry sand/rubber-wheel abrasion tester is widely used to evaluate the low-stress abrasion resistance of materials for the mining/mineral processing industry particularly for the oil sand mining industry. Since wear loss is usually proportional to the applied load, this test is often performed under a fixed load at a fixed sliding speed to rank materials. However, inaccurate or misleading information might be generated under an inadequate load. It has been observed that D2 tool steel exhibits very different responses to variations in the applied load. Above a certain load level, further increase in the applied load may lead to a decrease in wear loss of D2 steel. In order to understand this phenomenon, computer simulation was performed to investigate wear responses of several engineering materials, including D2 tool steel, stainless steel, Al 6061 and Cu 110, to variations in applied load under the dry sand/rubber-wheel abrasion condition. It was demonstrated that the decrease in wear loss of D2 tool steel with an increase in the applied load was attributed to failure of the abrasive sand. Wear losses of the materials with respect to the sliding speed were also investigated. The prediction from the simulation was compared to experimental observations.     

An investigation of the corrosive wear of stainless steels in aqueous slurries

Pumping installations made of stainless steels have been widely used for transporting slurries in chemical process industry. However, knowledge of the attack of stainless steels due to corrosive wear in two-phase liquid-particle flow is still incomplete. This paper studies the behaviors and mechanisms of corrosive wear for two austenitic stainless steels, 24Cr-25Ni-4Mo and 18Cr-12Ni-2Mo, using a rotating disc apparatus made by the authors. The two components, wear by slurry abrasion and corrosion, within the corrosive wear process, are first examined individually. Then the synergistic effect between wear and corrosion is investigated. The research we have done shows that corrosive wear rate of samples is closely related to such factors as the solution, type of abrasive, flow velocity, impingement angle and temperature. In addition, a threshold of flow velocity exists which is called the breakaway velocity V_k, above which the corrosive wear rate increases rapidly. The combined effects of abrasion and corrosion result in a total wear loss larger than the added effects of each process alone. An analytical model is developed which would help to reveal the mechanisms of the corrosive wear processes.     

Effects of microstructure and experimental parameters on high stress abrasive wear behaviour of a 0.19 wt% C dual phase steel

The present investigation is aimed at understanding the influence of the size and quantity of ferrite plus martensite on mechanical and abrasive wear properties in a 0.19 wt% C dual phase steel. The results indicate that the mechanical properties like strength, ductility and impact, as well as abrasion resistance of the samples are greatly influenced by the material and test conditions. For example, the samples involving prior annealing showed higher ductility but less strength over the normalized specimens. Also, the increasing intercritical annealing temperature led to superior strength associated with reduced ductility. The wear rate increased with load and abrasive size due to a larger depth of cut made by the abrasive medium. The wear rate decreased as sliding distance increased. The steel subjected to prior normalizing treatment attained superior wear resistance to that of the one subjected to prior annealing treatment. The wear rate also decreased with increasing intercritical annealing temperature from 765 to 805 °C with an exception that the steel treated at 805 °C exhibited wear rate comparable to the one treated at 765 °C when tested against coarser size (40 μm) abrasive.     

Evolution of friction-induced microstructure of SUS 304 meta-stable austenitic stainless steel and its influence on wear behavior

The microstructure evolution of the worn surface and sub-surface layer of SUS 304 austenitic stainless steel (ASS) disc against Al₂O₃ ceramic ball were studied on the basis of the tribological behaviors in the tests performed using a Cameron-Plint TE67 pin-on-disc tester. The microstructure after friction test was observed by optical and scanning electron microscope. The possible phase transformation of meta-stable austenite to martensite was detected by X-ray diffractometer. Results showed that friction-induced deformation led to finer grain at the subsurface beneath the worn surface. Furthermore, white layer was observed on some worn surface layers after higher normal loads. Transformed martensite from the austenite appeared on the worn surface under both low and high normal-loading conditions. Absence of transformed martensite was detected at the site about 25 μm below the worn surface although the grains at the site were still intensive and fine. In addition, the specific wear rate of SUS 304 stainless steel specimens was measured, and the possible reasons affecting the wear behavior were analyzed and discussed.     

Adhesive and abrasive wear behaviour of TiC alloyed,sintered, austenitic stainless steels

Abstract

This study examines abrasive and adhesive wear behaviour of austenitic stainless steel and its TiC alloyed composite produced through powder metallurgy technique. Abrasive wear tests have been carried out using a pin on disc wear tester under loads of 10, 20 and 30 N. For adhesive wear tests, a block on ring wear tester has been used under loads of 20, 40, 60 and 80 N. A possible correlation between the hardness, microstructure and wear behaviour of the samples has been investigated. The abrasive wear tests have revealed that the highest rate of mass loss occurred in the austenitic matrix stainless steel sample; also, mass losses decreased with an increased rate of reinforcing material in the composite. In adhesive wear tests, interparticle spacing developed from severe wear and extreme plastic deformation under heavy loads; however, at low loads, oxidation type wear was shown to be dominant.     

不同环境介质下氧化铝陶瓷与耐蚀金属摩擦磨损行为

为优选海水淡化高压泵关键零部件耐磨性能材料,以Al_2O_3陶瓷与TC4钛合金、316不锈钢、2205双相不锈钢组成的配对摩擦副作为研究对象,利用立式万能摩擦磨损试验机开展干摩擦、纯水及海水3种环境介质下配对材料的摩擦磨损试验,定量得到各摩擦副摩擦因数、磨损量,并对摩擦试样的表面形貌进行分析;采用正交试验法分析载荷、转速、环境介质对摩擦因数和磨损量的影响规律。结果表明:在相同的条件下,TC4钛合金与陶瓷配副摩擦因数较小,2205双相不锈钢与陶瓷配副磨损量较小;环境介质对摩擦因数影响较大,载荷对磨损量的影响较大;海水环境下2205双相不锈钢和316不锈钢磨痕较浅,磨损机制为疲劳磨损、磨粒磨损和腐蚀磨损的交互作用。     

Effect of Gradient Nanostructures on Tribological Properties of 316L Stainless Steel with High Energy Ion Implantation Tungsten Carbide

Surface gradient nanostructure of 316L stainless steel was prepared by ultrasonic surface rolling processing (USRP). WC were implanted into the gradient nanostructure surface by using high energy ion implantation technology (HEII). First, surface characteristics of two sets of specimens were investigated through hardness distribution, sectional morphology and microstructure. Then friction and wear mechanism was discussed. Results are as follows: the ion impregnated channels were obviously increased under USRP; hardness value of the top surface of USRP?+?HEII specimen was increased by 57.8% and thickness of hardened layer was increased by 100% comparing to HEII specimen; wear mass loss of USRP?+?HEII specimen was greatly reduced compared with HEII specimen; friction and wear mechanism of HEII specimen was changed from oxidation wear to fatigue wear, while the oxidation wear and adhesion wear were the main wear mechanisms for USRP?+?HEII specimen as the increase of rotational speed.     

Slurry Erosion Wear Resistance and Impact-Induced Phase Transformation of Titanium Alloys

Erosion wear resistance and impact-induced phase transformation of titanium alloys TA2 (pure Ti), TC4 (Ti–6Al–4V) and TC11 (Ti–6.5Al–3.5Mo–1.5Zr–0.3Si) were investigated using a slurry jet tester. The slurry erosion wear resistance of TA2 is comparable to that of 304 stainless steel, especially at the impingement angle 90°. Although TC4 and TC11 have higher hardness, TA2 possesses the best erosion wear resistance except TC11 at 15°. With the increasing erosion time, the eroded surface hardness of TC11 at the impingement angle 90° increases and then decreases, while the volume loss rate drops in the first 15 min, then increases until 30 min, and then slightly decreases again. With XRD characterization and SEM observation, erosion-induced phase transformation from metastable β-phase to α-phase is proved on the surface of titanium alloy TC11. And the thickness of visible phase transformation layer is about 10 μm. Phase transformation influences the erosive wear mechanism of titanium alloys. At the impingement angle of 30°, the material removal of TC4 and TC11 can be described as micro-plowing and lip extruding, while plowing mark is not a typical surface morphology of TA2, indicating a better work-harden ability. So, stabilizing β-phase can be an effective way to improve the erosion wear resistance of titanium alloys.     

Surface Hardness and Abrasive Wear Resistance of Ion-Implanted Steels

The hardnesses of nitrogen-implanted steel surfaces have been measured with an abrasive wear technique capable of characterizing surface layers as thin as 25 nm. Treated steel disks and reference disks were abraded with 1–5 μm diamond, and relative wear resistances were calculated from the mass losses. Surface hardness was obtained from a relationship between wear resistance and hardness.

The surface of a hardened and tempered carbon steel implanted with nitrogen ions (10¹⁷/cm²) was significantly harder than with other treatments including quench hardening and nitriding. The hardness decreased to the bulk value over a depth corresponding to the initial implantation depth.

Nitorgen-implanted stainless-steel surfaces wore faster than un-implanted ones, possibly due to interference with transformation hardening which normally occurs during wearing. This “softening” effect persisted to depths several times the depth of implantation, and may help to explain the reduction of sliding wear produced by the implantation of stainless steels. Analyses by Auger electron spectroscopy indicated nitrogen migrated toward the bulk during wear.

Titanium implanted in stainless steel (4.6 × 10¹⁷ ions/cm²) produced a very hard surface with more than 10 times the abrasive wear resistance of the bulk metal.     

Abrasive wear response of cryotreated EN45 steel in simulated wear test rig fixture

Wear by sand abrasion occurs in cutter blades of sugarcane cutting machine. The wear life of components used under sand abrasion conditions is governed by process parameters, properties of abrasive particles in the soil and material properties. In this article, the wear performance of conventionally and cryotreated specimens was tested in the soil containing 20% silica at different blade speeds such as 300, 400, 600 and 750?rev?min^??1 at the varied cutting times of 8, 16, 24 and 32?h respectively using simulated test rig fixture of sugarcane cutting machine. In addition, treated specimens were characterised for the microstructural features, hardness and surface roughness. Microstructural study indicated fine structure of tempered martensite with addition of segregation of silicon and carbon spots in the cryotreated specimen. The surface roughness of cryotreated material was decreased by 50% with respect to conventionally treated one. The mass loss of cryotreated cutting blades was reduced by 28% over conventional treatment at 750?rev?min^??1. The wornout surface and subsurface of conventionally treated specimens showed predominant dislodgment of wear particles.