Pin Abrasion Tests Research Articles

Design and development of a novel electrochemical abrasion-corrosion tester

Abstract Abrasive particle wear in corrosive environments is very common in offshore industry, e.g., dredging. The synergy or mutual effects between the abrasive and corrosive wear on material degradation cannot be quantified with standard tribological test equipment. A novel test rig has been developed, which couples pin abrasion test set-up (ASTM G132) along with three-electrode electrochemical system that allows to quantify experimentally the synergy between two-body multiple asperity abrasion and corrosion of metallic materials. The present article explains in detail the design and construction of this novel tribocorrosion test rig and discusses the results of investigation on an abrasion resistant martensitic steel in the presence and absence of corrosive medium resulting in higher wear in the latter condition.

Characterization of Reagent Pencils for Deposition of Reagents onto Paper-Based Microfluidic Devices.

Reagent pencils allow for solvent-free deposition of reagents onto paper-based microfluidic devices. The pencils are portable, easy to use, extend the shelf-life of reagents, and offer a platform for customizing diagnostic devices at the point of care. In this work, reagent pencils were characterized by measuring the wear resistance of pencil cores made from polyethylene glycols (PEGs) with different molecular weights and incorporating various concentrations of three different reagents using a standard pin abrasion test, as well as by measuring the efficiency of reagent delivery from the pencils to the test zones of paper-based microfluidic devices using absorption spectroscopy and digital image colorimetry. The molecular weight of the PEG, concentration of the reagent, and the molecular weight of the reagent were all found to have an inverse correlation with the wear of the pencil cores, but the amount of reagent delivered to the test zone of a device correlated most strongly with the concentration of the reagent in the pencil core. Up to 49% of the total reagent deposited on a device with a pencil was released into the test zone, compared to 58% for reagents deposited from a solution. The results suggest that reagent pencils can be prepared for a variety of reagents using PEGs with molecular weights in the range of 2000 to 6000 g/mol.

Remarks on the application of two-dimensional shape factors under severe wear conditions

Abstract The use of two-dimensional shape parameters to characterize abrasive particles is a potential approach to express their angularity. Nevertheless, in sliding abrasion, especially in pin abrasion testing, these descriptors could not be suitable for characterizing severe wear of engineering materials such as steels and cast irons. This work compares the applicability of two-dimensional shape parameters in describing severe wear of metals in recent pin abrasion tests with cases where they could have been correlated with the wear rates. Considering these aspects, this work puts in evidence the importance of clogging occurrence and the coated paper structure for a carefully application of shape parameters. In addition, it is proposed a possible relation between the shape parameters and one of the components of the abrasion factor.

Effect of normal load on abrasive wear resistance and wear micromechanisms in FeMnAlC alloy and other austenitic steels

Little attention has been paid to the role of stacking fault energy (SFE) in the two-body abrasive wear of austenitic steels. Using a pin-abrasion test with 220 grit garnet paper as the counterbody, three austenitic steels of different SFEs were compared. The steels were: (i) FeMnAlC, (ii) Hadfield steel, and (iii) AISI 316L steel. Following a pre-conditioning procedure, the normal loads on the 3mm diameter test pins were 5N, 10N and 15N, and the sliding speed along a spiral track of total length 430m was 0.158m/s. Data showed that the FeMnAlC steel had a higher wear resistance than AISI 316L steel but lower wear resistance than the Hadfield steel. However, at the highest test load, all three steels had similar wear resistance. The steel with the lowest SFE had the highest abrasive wear resistance and the steel with the highest SFE had the lowest abrasive wear resistance. The main wear mechanisms were microcutting and microploughing. There was a transition from microploughing to microcutting as the normal load was increased.

Heat treatment and two-body abrasion of Ni-Hard 4

The two-body abrasion behaviour of three Ni-Hard 4 alloys after destabilisation and subcritical heat treatments was studied. The destabilisation treatment was carried out at 820°C for 4h followed by air cooling to room temperature. The subcritical treatment was carried out at three temperatures of 300, 450, and 550°C for 4h and then air cooling to room temperature. Using a pin abrasion test, the alloys were abraded on three types of bonded abrasives (silicon carbide, corundum, and flint). The results showed that the abrasive used had an essential effect on the wear resistance of the alloys. The as-hardened microstructure containing a retained austenite of 27% exhibited the greatest abrasion resistance, whereas the as-tempered at 550°C gave the worst. Very poor correlations were found between the abrasion resistance and bulk hardness of test alloys. Therefore, a general model “equivalent hardness” was developed to explain the abrasion behaviour. In this model, the influence of matrix work hardening due to abrasion was highlighted. The equivalent hardness equals the sum of the products of the volume fraction of each phase (matrix and carbide) and its microhardness; the hardness of the abraded matrix was considered. Strong correlations were found between the abrasion resistance and equivalent hardness of test alloys.

Comparison of abrasive wear in diamond composites and WC-based coatings

The abrasive wear of a series of diamond and tungsten carbide (WC)-based metal matrix composites has been examined using both low stress scratching abrasion (rubber wheel) and high stress grinding abrasion (pin-on-flat) tests. The hardfacings consisted of two diamond-based composites and four WC-based composites, which contained a variation in volume fraction and size of the hard phase. Measurements of wear loss have been correlated with the microstructural characteristics of the hard phase and the matrix. The rubber wheel and pin abrasion tests have produced a similar mechanism of wear in both the diamond and WC-based composites. The abrasive wear loss in both the diamond and WC-based composites has been shown to decrease sharply by a factor of 5 with increase in mean size and volume fraction of the hard phase irrespective of the type of particles. Wear loss has shown little correlation with the variation in hardness of the matrix within the series of composites.

Effect of load and carbide orientation on abrasive wear resistance of white cast iron

In this study, white cast iron with 7.39% Cr was casted into an exothermic mold on a copper chill plate to solidify unidirectionally. The microstructure is composed of oriented M3C carbides and ledeburitic matrix. The specimens were cut both parallel and transversally to the billet axe and pin-abrasion tests were carried out using fixed alumina abrasive grains at loads between 2 and 15 N. The microhardness, elastic modulus and fracture toughness were determined using an indentation technique on transversal and longitudinal directions. The abrasion resistance was correlated with the carbides microhardness and fracture toughness. The M3C carbides showed similar values of fracture toughness in both directions. The carbides in transversal direction showed higher hardness and elastic modulus than longitudinal carbides. The results reveal that for lower loads the mass loss is similar in both directions. However, for loads higher than 10 N the M3C carbides in the transversal direction show higher abrasion resistance than longitudinal carbides. The wear surface was examined by scanning electron microscopy for identifying the wear micromechanisms. Bending and slip planes on longitudinal cementite were observed at 15 N.

Effect of (Fe,Cr)7C3 carbide orientation on abrasion wear resistance and fracture toughness

Abstract In this study two white cast irons with different chromium contents 13.81% and 24.41% were solidified unidirectionally. Their microstructures are composed of oriented M 7 C 3 carbides and eutectic matrices. The specimens were cut parallel and transversally to the billet axe and pin-abrasion tests were carried out using fixed alumina abrasive grains. The microhardness, elastic modulus and fracture toughness were determined using an indentation technique on transversal and longitudinal sections of the M 7 C 3 carbides. M 7 C 3 carbides show higher microhardness in transverse than in longitudinal direction. Longitudinal M 7 C 3 carbides show higher fracture toughness in the direction perpendicular to the larger edge of the carbide than either parallel to the larger edge or on the transverse section. The results reveal that the white cast iron presents higher abrasion resistance in transverse section than in longitudinal section of the M 7 C 3 carbides. The wear surface was examined by scanning electron microscopy for identifying the wear micromechanisms and was correlated with the fracture toughness of the carbides. The results show that when the carbides fracture, the cracks propagate parallelly to the larger edge of the M 7 C 3 , the direction where the fracture toughness is lower.

Load effect in abrasive wear mechanism of cast iron with graphite and cementite

In this study four irons were casted with different chromium and vanadium contents: 2.66% Cr, 5.01% Cr, 2.51% V and 5.19% V. Their microstructure is composed of: ledeburite, graphite and M 3C carbides (cementite). Pin-abrasion tests were carried out using fixed alumina abrasive grains at different loads: 1, 2, 4.6 and 10 N. The wear surface and the abrasive paper were examined by scanning electron microscopy for identifying the wear micromechanism. The results reveal that the mass loss increased with the load increase, and the effect of the percentage of chromium on mass loss is inverted when the load is increased from 4.6 to 10 N; for 4.6 N the mass loss decreased when the chromium percentage was increased from 2.66% to 5.01%. Nevertheless, for 10 N the mass loss increased when the chromium percentage was increased. The worn surfaces of the materials tested at 1 N show microcutting caused by the abrasive tip that produces continuous microchips. The worn surfaces and the abrasive paper tested at 10 N show continuous microchips and brittle debris. The results show that high pressures produce a brittle wear mechanism and low pressures produce a more ductile wear micromechanism, for this, the applied pressure defines the dependence between the wear resistance and wear micromechanism.

Abrasive wear of steel against gravel with different rock–steel combinations

Wear testing equipment and tests used in research laboratories are often miniature or simplified versions of real applications. For example standardized ASTM dry sand rubber wheel abrasion test G 65 and pin abrasion test G 132 are widely used to study materials’ abrasion wear resistance. The test results, however, do not always correlate too well with the results obtained from real wear conditions. One reason for this is, for example, that in the crushing applications of mining industry the abrasive size is usually much larger than that used in the laboratory wear tests. To study the abrasive wear caused by larger size gravel, new three-body abrasion test equipment was therefore constructed. The equipment uses the pin-on-disk principle with free abrasive particles of sizes up to 10 mm. During the test the pin is repeatedly pressed against a fixed amount of abrasive that is rotating with the disk having confining walls. As the pin is prevented from touching the counterbody, only the abrasive acts as the wearing agent. Three steels of different hardnesses were cross-tested as pin–disk pairs and as pins against a rubber disk using three igneous rock gravels with different crushability properties as abrasives. The wear was measured as mass loss from both the pin and the disk, and the rock comminution was measured by sieving. The results indicate that the mechanism of wear is greatly affected by the hardness of the counterbody. When using large size abrasives, the rate of comminution is also a very important factor that can significantly affect the wear test results.

Two-body abrasive wear property of cementite

The abrasive wear property of single-phase cementite and cementite–iron composite, processed by mechanical alloying and spark plasma sintering, were investigated using a pin-abrasion test on fixed alumina abrasive grains. Single-phase cementite and cementite–iron composite had good wear resistances at applied pressures lower than 0.15 MPa. However, at applied pressures higher than 0.31 MPa, steels having a cementite volume fraction higher than 75% were intensely worn. In the former case, the wear mode of bulk cementite was ductile, and flow-type chips were observed on the worn surface. In the latter case, the wear mode was brittle, and brittle fracture chips were observed on the worn surface.

Wear of iron–aluminide intermetallic-based alloys and composites by hard particles

In this study, the resistance of alloys and composites based on the intermetallic compounds Fe 3Al and FeAl to wear by hard particles was assessed and compared to the behavior of selected metals, alloys, other intermetallic compounds and ceramics. Pin abrasion tests were performed on these materials at room temperature. Among other things, it was found that as the Al atomic percent in binary Fe–Al increased, the alloys became more abrasion resistant. In summary, the ranking of the alloys in terms of abrasion resistance from the most resistant to the least resistant proceeds as follows: FeAl>Fe 3Al>α-Fe alloy with 16 at.% Al>pure Fe>pure Al. These results are discussed in terms of the hardnesses of the respective alloys. The addition between 40 and 70 vol.% of a hard second phase (e.g. TiC or TiB 2) decreased the wear rate of the Fe 3Al and FeAl composites by an order of magnitude compared to the parent alloy. In addition, solid particle erosion tests were performed on an FeAl alloy, and FeAl+80 vol.% TiC, FeAl+80 vol.% WC, FeAl+80 vol.% TiB 2 cermets at 25, 180, 500 and 700°C, and the results were compared to erosion behavior of several conventional alloys and cemented carbides (WC–Co). The ranking of the erosion resistance of the FeAl alloys and composite materials was as follows: (most resistant) FeAl–WC>FeAl–TiB 2>FeAl–TiC>FeAl (least resistant). This behavior was related to both the cermet microstructure and material removal mechanisms.

The effect of heat treatment on the abrasion resistance of alloy white irons

The effect of the temperature and time of the destabilization and sub-critical heat treatments on the abrasive wear behaviour of two high-chromium white iron alloys (15-3 CrMo and 27 Cr) was investigated. The response of each alloy to the destabilization heat treatment and, therefore, the microstructures developed, differed significantly. Pin abrasion tests were conducted, and showed the wear resistance of the 15-3 CrMo alloy to be superior to that of the 27 Cr alloy for most conditions. Following abrasion testing, retained austenite measurements using X-ray diffraction and microhardness measurements on the wear pins indicated the extent of austenite transformation and work-hardening. The work-hardening due to abrasion was greater for the 15-3 CrMo alloy and this was related to the difference in composition of the matrix of each alloy. Abrasion on garnet and on alumina produced similar levels of work-hardening for both alloys, despite the differences in the abrasive hardness. Sub-critical heat treatments increased the abrasive wear loss. In particular, the formation of ferrite/carbide aggregates during the sub-critical heat treatment greatly increased the wear rate.

Verfestigung und Verschleißverhalten von weißen Gußeisen bei abrasiver Beanspruchung

AbstractWeiße Gußeisen werden häufig dort eingesetzt, wo starke abrasive Belastung auftritt. Die Mikrostruktur und die mechanischen Eigenschaften dieser Legierungen spielen eine wesentliche Rolle, um die durch Verschleiß verursachten Verluste zu kontrollieren. Hinsichtlich der mechanischen Eigenschaften wird in zahlreichen Veröffentlichungen berichtet, daß die Werkstoffhärte allein das Verschleißverhalten nicht bestimmt. Dabei gilt allgemein, daß die während des Verschleißvorganges entstehende Verfestigung den Verschleißwiderstand wesentlich beeinflußt.In der vorliegenden Arbeit werden Ni‐Hard 4 und hochchromhaltige weiße Gußeisen bezüglich ihres Verschleißverhaltens anhand eines Schleifpapierverfahrens untersucht. Die Ergebnisse dieser Untersuchungen tragen u.a. zur Klärung der Korrelations mechanismen zwischen Oberflächenverfestigung und abrasivem Verschleißverhalten bei.

Abrasion resistance of in situ Fe-TiC composites

Metal matrix composites containing a high volume fraction of carbide, nitride, boride, and/or oxide particles are frequently the materials of choice for applications which require high wear resistance. It is the very hard second phase particles which imbue the metal matrix composite with its superior wear resistance. For example, additions of titanium carbide (TiC), one of the hardest of the carbides with a Vickers hardness of 19.6--31.4 GPa, can be used to improve the abrasion resistance of iron alloys. In the present study in situ metal matrix composites, containing between 23 and 31 volume percent carbides, were produced from Fe-Ti-C and Fe-Cr-Ti-C melts, and their abrasion resistance was compared with that of unreinforced Fe and a white cast iron using a high-stress pin abrasion test.

Evaluation of commercial US grinding balls by laboratory impact and abrasion tests

Impact and abrasion properties of various commercial US grinding balls were evaluated and compared by the Bureau of Mines, US Department of the Interior. Laboratory tests were conducted on balls obtained from eight major US manufacturers. The balls included forged steel, cast steel, and alloyed white cast iron and were subjected to repeated impacts until they broke or until 300,000 impacts were exceeded. Pin abrasion tests also were conducted. The results showed wide differences in impact lives, ranging from a few thousand to over 500,000 impacts. The life of inferior commercial balls was increased five to six times by a laboratory tempering heat treatment. For balls that did not break, the major impact wear mode was spalling and ranged from an average rate of 0.28 to 4.46 mg per impact. The softest balls (steel) had excellent impact resistance but low abrasion resistance. The abrasion resistance of the steel balls generally increased with hardness. The alloyed white cast irons had about twice the abrasion resistance of the steel balls. Users should become aware of the wide variations among commercial balls, and ball manufacturers should be aware that their product can be improved.

A Pin-on-Drum Abrasive Wear Test and Comparison with Other Pin Tests

Abstract The Bureau of Mines, in its ongoing effort to combat the wear of mining and mineral processing equipment, has used several types of laboratory wear tests. Investigations into existing pin abrasive wear testing machines resulted in the construction of the Bureau's own pin-on-drum wear testing apparatus, incorporating the best features of the previous designs. Comparisons of pin diameters, loads, and other factors are made between the Bureau of Mines' pin-on-drum test and other pin abrasion tests. The effects of variations in abrasiveness over the drum were essentially eliminated by making corrections based on the wear of a standard pin traveling a parallel path. Reproducibility of wear values on homogeneous alloys was generally within ±0.5%. Statistical analyses and test procedures are given for heterogeneous alloys. Design parameters for future pin abrasion tests are recommended.

Gouging and sliding abrasion of austenitic manganese steels reinforced by hard phases

Boron in austenitic manganese steels leads to the formation of (Fe,Mn) 3(B,C) carboborides arranged in a cell-type microstructure. Gouging abrasion tests with a modified 300 J Charpy impact tester (copy of the “Uppsala pendulum”) reveal that these carboborides do not improve the wear resistance. This originates from their relatively low hardness compared with the work-hardened matrix, from a weak bonding to the austenite as well as from favourable conditions for unimpeded crack propagation and crack branching within the carboboride cell walls. However, pin abrasion tests on flint abrasive paper show that carboborides, hardened, for example, by additions of vanadium, substantially increase the abrasive wear resistance. This results from a supporting effect of the hard phase cell structure on the abrasive agent which consequently impedes wear of the softer matrix.

Abrasive wear resistance of boron alloyed austenitic Fe—Mn—C‐steels

Alloying additions of 0.25–1.0 wt‐% B to austenitic manganese steels lead to the formation of carboborides arranged in a cell‐type microstructure. Pin abrasion tests on flint grinding paper using different dead weight loads reveal that these carboborides do not substantially improve the wear resistance due to a relatively low hardness and weak bonding to the austenite matrix. However, carboborides hardened by V, e.g., can considerably increase the abrasive wear resistance. They are very effective in a metastable austenitic matrix in which friction‐induced martensitic transformation occurs. It is the consequence of compressive stresses in the martensitic surface layer which improve the anchoring of insufficiently bonded carboborides in the matrix.

Wear Behavior of Iron and Steel Castings for the Mining Industry

The abrasive wear resistance of a large group of cast steel and white iron grinding mill liners was studied using a combination of service and laboratory testing. The hardness of the liners was the metallurgical variable which correlated best with the weight losses experienced during both service exposure and pin abrasion tests. Chemical and microstructural variations were much less significant in their effect upon the relative wear within the groups of either steel or iron liners, although such variations were important in the basis for the markedly lower laboratory wear rate of the white iron liners as a group. A strong correlation was found between the weight losses measured in laboratory tests and in service, and thus it appears possible to predict the service performance of new liner materials in the subject application based upon prior laboratory testing.