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The running-in period during dry sliding wear might determine the evolution to steady-state wear behaviour. To this end, the running-in period during sliding wear of austenitic stainless steel, AISI 316L stainless steel, and Hadfield steel were studied through the testing pin (flat-ended)-on-disk configuration. The effects of the normal load, sliding speed, and alloy type were assessed, and the specific wear rate and strain hardening characteristics were determined. The wear rate was correlated with wear mechanism, friction coefficient, hardening, and roughness to characterize the changes occurring during the running-in period. These changes could influence the responses of these materials to wear during the steady-state period. The stabilization of the specific wear rate and hardness was noted to align with the end of the running-in period. [ABSTRACT FROM AUTHOR]

Tool steels are well known to have superior strength and are claimed to have superior wear resistance than conventional steels in several scenarios. However, their behavior under slurry erosion conditions have been seldom studied. To this end, a set of tool steels, primarily from the CPM yV (y = 1, 3, 9, 10, 15) alloy family, was selected to understand the effect of hardness and vanadium carbide content on the slurry jet erosion (SJE) performance at different impingement angles. It was observed that the SJE resistance increases with the increase in the vanadium carbide volume fraction, but is independent of alloy hardness. [ABSTRACT FROM AUTHOR]

In the present work, the dynamic recrystallization and microstructural evolution of the family of advanced high-strength steels Fe18MnxAl0.74C are studied, varying the aluminum content in 0, 3, 6, and 9 wt pct subjected to hot-forging treatments through three consecutive heating-deformation cycles. For characterization, X-ray diffraction (XRD), Mössbauer absorption spectroscopy (MAS), and electron backscattering diffraction (EBSD) were used. It was determined that for the steels under study, dynamic recrystallization occurs due to strain-induced boundary migration (SIBM) and is strongly influenced by the aluminum content of the alloy and its stacking failure energy (SFE), increasing that the aluminum content will generate greater nucleation sites, favoring the refinement of grains in the material and achieving a crystalline structure of random crystallographic orientation. The results are discussed throughout the article, allowing us to determine potential processing routes for advanced high-strength steels with predominantly plastic deformation mechanisms such as transformation-induced plasticity (TRIP), twinning-induced plasticity (TWIP), and microband-induced plasticity (MBIP). [ABSTRACT FROM AUTHOR]

The microstructural evolution of the two austenitic alloys Fe–20Mn–3Al–0.7C wt pct and Fe–20Mn–6Al–0.7C wt pct when different thermal and thermomechanical treatments are performed has been studied. To this end, a generic industrial die of 100 ton capacity and a Gleeble 3800 simulator were selected to perform the thermomechanical treatments. A solubilization treatment was carried out at 1100 °C for 4 days for the two alloys in as cast state. In addition, the specimens deformed with the industrial die underwent a solubilization treatment at 1100 °C for 4 hours. Microstructural characterizations were performed by X-ray diffraction, transmission Mössbauer spectrometry, and electron backscatter diffraction. The results showed both the formation of different austenites rich and poor in solute atoms, as well as different microstructures, as a function of the treatments performed, which affected the resulting dynamically recrystallized microstructures. Notably, it was observed that it is possible to explain and relate the evolution of the microstructure to the hyperfine parameters resulting from fitting the Mössbauer spectra. In particular, the relationship between the degree of dynamic recrystallization and the evolution of an ordered austenitic structure is discussed. [ABSTRACT FROM AUTHOR]

In the mining and related industries, the abrasion and impact phenomena operate among the chain of ore processing. While abrasion-corrosion and/or erosion-corrosion phenomena in ore processing are relatively well understood, the concurrent operation of abrasion and impact wear is not well comprehended. The distinctive mechanisms and features of abrasion-impact wear and the synergy, if one exists, between impact and abrasion have not been either explored or discussed systematically in the literature. Furthermore, their economic impact on mining cannot be underestimated especially as past research focused mainly on improving the hardness even at the expense of toughness. Understanding the complex relation between abrasion and impact can efficiently mitigate countless wear problems in mining. The purpose of this paper is to discuss critically the topic, stimulating new questions, and propose some general ideas that might be used as basic guidelines. [ABSTRACT FROM AUTHOR]

During the last years, the scientific and industrial community has focused on the astonishing properties of Fe-Mn-Al-C steels. These high advanced steels allow high-density reductions about ~ 18% lighter than conventional steels, high corrosion resistance, high strength (ultimate tensile strength ~ 1 Gpa), and at the same time ductility above 60%. The increase in the tensile or yield strength and the ductility at the same time is almost a special feature of this kind of new steels, which makes them so interesting for many applications such as in the automotive, armor, and mining industry. The control of these properties depends on a complex relationship between the chemical composition of the steel, the test temperature, the external loads, and the processing parameters of the steel. This review has been conceived to elucidate these complex relations and gather the most important aspects of Fe-Mn-Al-C steels developed so far. [ABSTRACT FROM AUTHOR]

Multilayer effect was studied systematically on the carbon-nitride system and its effect on the flank wear of cutting inserts. In this sense, tungsten carbide (WC) inserts were used as substrates to improve their tribological properties. The heterostructure coatings were grown via reactive r.f. magnetron sputtering technique by methodically varying the bilayer period (Λ) and the bilayer number (n) while maintaining constant the total coating thickness (~ 3 μm) of the films. The heterostructures were characterized by transmission microscopy (TEM), and the wear tests were supported by scanning electron microscopy (SEM), and laser interferometry. The results showed that the increase of (n) produced a significant increase of the wear resistance in both laboratory wear tests and in real wear tests. In summary, these results encourage the use of the [TiCN/TiNbCN]n system as coatings for machining tools with a drastic enhancement of the wear life. This work has seldom been addressed in literature focused on the tribological properties of the carbon-nitride system. [ABSTRACT FROM AUTHOR]

The wear behavior of two high-speed steels and a high-chromium cast iron with cryogenic treatments was evaluated using a pin-on-disc configuration. An ASTM A36 steel disc, oxidized previously in a furnace at 950 °C, was used as a counterbody with the goal of developing an accurate representation of the industrial calamine formed on the surface of steels under industrial conditions. This is a new perspective to evaluate the real contribution of the normal load, sliding velocity and heat treatments on the wear phenomena of hot rolls. Optical microscopy, scanning electron microscopy and X-ray diffraction were used to correlate the wear rate, friction coefficient and wear mechanisms to the microstructure, hardness and types of oxides that formed on the counterbody. Experimental results showed a complex relation between the normal load, the sliding velocity and the interaction with counterbody, which establishes the wear rates and friction coefficients. [ABSTRACT FROM AUTHOR]

This research analyses the effect of the microstructure of mottled cast iron on tribological behaviour using a high temperature pin-on-disc test with a steel disc oxidised at 1,200 °C ASTM A36 as a counterbody. Three different microstructures were obtained for the mottled cast iron pins by quenching and tempering at 400 °C and 600 °C. The test temperature was varied from 200 to 600 °C with the aim of approximating the temperatures reached on surface work rolls under industrial conditions. The oxidation of the ASTM A36 disc at 1,200 °C was used to reproduce a counterbody (calamine) similar to that occurring in the hot roll mill steel under industrial conditions. The other tribological test parameters were held constant (normal load of 20 N and sliding speed of 0.05 m/s). The experimental results at the lowest test temperature (200 °C) show that the wear strongly depends on the microstructure and that the greatest friction coefficients are present at this condition. However, at higher test temperatures (400 and 600 °C), the wear resistance depends on the pin oxide stability. The highest wear rate occurs at a test temperature of 400 °C, and the lowest wear rate occurs at 600 °C. The explanations for these phenomena are discussed. [ABSTRACT FROM AUTHOR]

OBJECTIVES: The purpose of this study was to compare the chemomechanical caries-removal system (Carisolv) with high-speed excavation in cavitated occlusal caries of primary molars. Design and setting. The study was a randomized controlled, clinical trial in which the two techniques were compared in each subject. Participants were chosen from public schools, in Maracaibo County, Zulia State, Venezuela. SAMPLE AND METHODS: The sample consisted of 80 primary molars selected from 40 children (mean age 7.7+/-0.7 years). Each patient had at least two contralateral primary molars with cavitated occlusal caries and approximately equal-size access to lesions. The outcome variables were: clinically complete caries removal, size of the opening of the cavity, volume of carious tissue removed, pain during caries removal, anaesthesia requested by the patient, caries-removal time, and behaviour and preference of patients. RESULTS: All treated molars were clinically caries free whichever caries-removal procedure was used. When Carisolv' was used the final cavity entrance sizes were smaller (P<0.001) and the estimated volume of tissue removed was less (P<0.001). The time taken for caries removal was three times longer (7.51+/-1.83 min, P<0.001). Some pain was reported by seven (17.5%) participants when Carisolv was used, compared with 16 (40%) when high-speed excavation was used (P<0.05). Using the Carisolv method there was a higher proportion of patients with positive behaviour (P<0.01), and 71.0% (P<0.05) preferred this treatment. CONCLUSION: Carisolv is an effective clinical alternative treatment for the removal of occlusal dentinal caries in cavitated primary molars; it is more conservative of dental tissue and appeared to be more comfortable for most patients, although the clinical time spent is longer than when using high-speed excavation. [ABSTRACT FROM AUTHOR]

Objectives. The purpose of this study was to compare the chemomechanical caries-removal system (Carisolv™) with high-speed excavation in cavitated occlusal caries of primary molars. Design and setting. The study was a randomized controlled, clinical trial in which the two techniques were compared in each subject. Participants were chosen from public schools, in Maracaibo County, Zulia State, Venezuela. Sample and methods. The sample consisted of 80 primary molars selected from 40 children (mean age 7·7 ± 0·7 years). Each patient had at least two contralateral primary molars with cavitated occlusal caries and approximately equal-size access to lesions. The outcome variables were: clinically complete caries removal, size of the opening of the cavity, volume of carious tissue removed, pain during caries removal, anaesthesia requested by the patient, caries-removal time, and behaviour and preference of patients. Results. All treated molars were clinically caries free whichever caries-removal procedure was used. When Carisolv‘ was used the final cavity entrance sizes were smaller ( P<0·001) and the estimated volume of tissue removed was less ( P < 0·001). The time taken for caries removal was three times longer (7·51 ± 1·83 min, P < 0·001). Some pain was reported by seven (17·5%) participants when Carisolv was used, compared with 16 (40%) when high-speed excavation was used ( P < 0·05). Using the Carisolv method there was a higher proportion of patients with positive behaviour ( P < 0·01), and 71·0% ( P < 0·05) preferred this treatment. Conclusion. Carisolv is an effective clinical alternative treatment for the removal of occlusal dentinal caries in cavitated primary molars; it is more conservative of dental tissue and appeared to be more comfortable for most patients, although the clinical time spent is longer than when using high-speed excavation. [ABSTRACT FROM AUTHOR]

In this study, three types of abrasives and several types of heat treatments and materials were used to obtain 11 different abrasive/material hardness (Ha/Hm) ratios with the aim of elucidating the effect of the Ha/Hm ratio on the mild-severe wear transition in erosion wear. This effect has seldom been addressed in the erosion wear literature focused on metallic materials. Solid particle erosion wear tests were performed. The experimental results showed different wear regimes when the Ha/Hm ratio was modified based on the fracture toughness of the erodent material (KIc); a moderate wear regime was observed for modified HaKIc_abrasive/Hm ratios less than 2, while a severe-moderate transition was observed for values between 2 and 4. The wear surface observations revealed a relationship between the wear erosion regimes and the wear micromechanisms. For the moderate wear regime, only superficial grooves and a slight plastic deformation were observed; for the transition wear regime, deeper grooves and craters were observed. Finally, in the severe wear regime, the deepest grooves and craters were observed, as were plastic deformation and cutting. [ABSTRACT FROM AUTHOR]