Effect of Cold Rolling on the Fretting Wear Behavior and Mechanism in Inconel 600 Alloy

The fretting test was carried out using an SRV IV fretting test rig in order to investigate the fretting wear behavior and mechanism in Inconel 600 alloy at room temperature. The materials were rolled to different reductions before the test. The effect of cold rolling on the friction coefficient and wear volume was subsequently investigated. The surface and cross-sectional morphologies of the wear scar were studied by scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and electron back-scattering diffraction (EBSD). The results indicated that the cold rolling had a different effect on wear behavior in different slip regimes. In the stick regime, cold rolling strongly decreased the wear volume, although it did not affect the friction coefficient. The 25% rolled specimen had the minimum wear volume. The mechanisms of as-received and 50% rolled specimens were delamination and oxidation wear, whereas for the 25% rolled specimen, cracking was the main wear mechanism. In the gross slip regime, cold rolling had little effect on the friction coefficient or wear volume. The fretting wear process gave rise to a decrease in the Σ3 grain boundary, an increase in local misorientation, and a change in the crystal orientation.     

Fretting wear behaviour of polymethylmethacrylate under linear motions and torsional contact conditions

The fretting wear behaviour of PMMA against a rigid counterface has been investigated under various contact zone kinematic conditions. A specific device has been used in order to achieve load axis spin or stationary rolling motions in a contact between a PMMA flat and a steel ball. Wear processes under such conditions have been investigated by means of laser profilometry and in-situ optical observations of the contact area during tests. Very different wear patterns were produced depending on the contact kinematics. For stationary rolling conditions, the progressive accumulation and compaction of debris induced the formation of a single ripple located in the middle of the contact. Very little debris was found to be eliminated from the contact and the resulting wear was quite low. On the other hand, little accumulation of debris was observed for torsional contact conditions and the wear was drastically enhanced. These results are analysed by considering the effects of contact zone kinematics on particle detachment and third body elimination.     

Fretting wear in seawater

Fretting tests of bearing steel (SUJ-2) and ceramics (Al₂O₃ and Si₃N₄) were carried out in the following environments: air, deionized water, 3.07% NaCl solution, synthetic seawater and natural seawater. Also, investigations to determine the optimum fretting wear resistant material for ships, marine equipment and offshore structures were conducted. The results showed that (1) the corrosion products formed in seawater behaved as a lubricant and reduced the fretting damage at large amplitudes, but the fretting damage was not greatly influenced by the different environments at very small amplitudes (such as 14 μm), (2) instead of natural seawater, synthetic seawater was adequate for the investigations of fretting wear, but 3.07% NaCl solution was found not to be and (3) the ceramic Al₂O₃ was a potentially useful material against fretting wear under light loads in seawater.     

Effect of grain size and hardness on fretting wear behavior of Inconel 600 alloys

The effects of grain size and bulk hardness on fretting wear behaviors were investigated by solution annealing and subsequently fretting wear test in Inconel 600 alloys. The results indicated that, with increase of solution temperature, the grain size increased while the hardness decreased. The average friction coefficients were the almost same, independent of grain size and hardness; while the wear volume decreased with increase of grain size, but the hardness played little role. The smaller grain was conductive to formation of tribological transformed structure (TTS) layer, and produced shorter delamiantion cracks in the TTS layer than larger one.     

Techniques in the study of impact and sliding wear of Zircaloy-4

A wear test apparatus has been designed to conduct detailed measurements of the contact forces and motion during impact and sliding (and combinations of the two). After carrying out pure impact and sliding tests on Zircaloy-4 couples in air at room temperature, it appears that the test apparatus has acceptable dynamic characteristics for wear studies.In pure impact, the wear rate of Zircaloy-4 was primarily influenced by the initial impact force which was measured dynamically. Secondary vibrations had a minimal effect on the wear rate.The wear rate in pure sliding was dependent upon the characteristics of the apparatus, such as its compliance, and the test conditions. Consequently the sliding amplitude should be monitored continuously throughout the test. In general, sliding wear was more severe than impact wear and good correlation between the average sliding amplitude and weight loss was observed. An indication of the relative motion between the wear specimens was given by the magnitude and form of the coefficient of friction which tended to increase with weight loss.     

Fretting wear of sintered alumina

Cylinders of alumina, carbon steel, glass and tungsten carbide have been fretted against rectangular specimens of sintered alumina. The damage caused has been assessed by four-point loading bend tests. Coefficients of friction of the contacting surfaces have been measured. These vary from 0.32 to 0.85 but do not correlate with the strength results. Alumina, glass and tungsten carbide produce no effect in fretting. This is due to the absence of adhesion between the surfaces. Fretting against steel increases the bend strength owing to blocking of the surface pores by iron.     

Inconel 600封头冲压加工

镍基特种合金耐蚀性好 ,在化工容器中得到广泛应用 ,但其制造技术要求高 ,尤其是封头的加工成形有难度。本文结合工程实践介绍了Inconel 6 0 0的材料特性、冲压工艺、缺陷处理以及探讨了热处理的适宜性等内容。     

Fretting wear of laterally supported tube

The fretting wear of a tube, which is in contact with a lateral support, is examined experimentally. A fretting wear tester is specifically designed. Elastic springs are used as the support, which can simulate the contact between a spacer grid and a fuel rod in pressurized water reactor fuel. The tubes and the springs are made of Zircaloy-4. The experiments are conducted in air at room temperature. The experimental conditions, i.e. the normal and shear forces on the contact, the slip range and the number of cycles, are set to be the same. To investigate the influence of the contact geometry on the wear, the spring supports have a concave, a flat or a convex contour. The influence on the axial and transverse slip directions is investigated to incorporate the actual tube motion caused by such a flow-induced vibration in the reactor. The wear on the tube is examined by the surface roughness tester, which measures the depth, and the contour of the worn surface of the tube. Since the shape and the distribution of wear are found arbitrary, a method for evaluating the wear volume is proposed using the signal processing technique. It is found that wear can be restrained when the slip direction is transverse, and if the support has a concave contour.     

Fretting wear and friction behaviour of engineering ceramics

Friction and wear characteristics of partially stabilized zirconia (PSZ) fretted against itself and against high carbon steel were investigated. The results for the transformation toughened PSZ ceramics are compared with the behaviour of more brittle alumina ceramic under the same test conditions. Fretting tests in air were carried out on a high frequency wear test rig at room temperature using a cross-cylinder configuration. It was found that both the oxide ceramics were more resistant to fretting wear than the steel. Surface cracking was observed on the alumina wear scars while microfracture and delamination dominated on the PSZ wear scars. When metallic samples were fretted against ceramics, metallic film transfer to the ceramic surfaces occurred.     

Fretting fatigue crack initiation and propagation behavior of Inconel 690 alloy

Several studies have been conducted on the fretting fatigue limit characteristics of Inconel alloy tube material used in steam generators of nuclear power plants. Nevertheless, additional research on fretting fatigue crack initiation and propagation behavior is necessary in order to evaluate its fretting fatigue life more accurately. In this study, crack growth tests of fretting fatigue are conducted, and the characteristics of fatigue crack initiation and propagation are analyzed on Inconel 690 alloy. Also, plain fatigue crack growth tests are performed on the same material, and the results are compared with those of fretting fatigue crack growth tests. From both of the plain and fretting fatigue crack growth test results, the ΔK-da/dN diagrams are obtained and the crack growth rates are compared. It is found that the crack growth rate for fretting fatigue tests is faster than that for plain fatigue tests under a certain value of DK. However, over this value of DK, the crack growth rate for fretting fatigue tests becomes slower than that for plain fatigue tests due to debris which is produced by fretting and trapped in the propagated cracks. Finally, the fracture surfaces examined by an optical microscope, and the initiation angles of the oblique cracks are determined under various applied stresses. Also, the microstructure of the fracture surfaces is observed by a Scanning electron microscopy (SEM).     

Fretting wear of Al-Si alloy matrix composites

Ball-against-disk type fretting wear tests for Al-Si alloy matrix composites in contact with bearing steel were conducted in wet air to investigate the effects of relative slip amplitude on friction and wear of the composites. In the larger range of relative slip amplitude, the Al-Si alloy-impregnated graphite composite (ALGR-MMC) shows lower friction coefficients than those of alumina short fiber-reinforced composite (ASFR-MMC) and hollow silica particle-reinforced composite (HSPR-MMC). Although the wear rate of the ALGR-MMC is higher than that of the ASFR-MMC and HSPR-MMC, the composite hardly causes damage to the mating material due to adhesion of compacted films of graphite powder and Al-Si alloy wear particles.     

Fretting wear behaviors of a railway axle steel

Fretting damage was one of the most important reasons for the failure of the railway axle. Fretting wear (tangential fretting mode) tests of a railway axle steel (LZ50 steel) flats against 52 100 steel balls were carried out under different normal loads and displacement amplitudes on a hydraulic fretting wear rig. Dynamic analyses in combination with microscopic examinations have been performed. The experimental results showed that the fretting regimes of the LZ50 steel were strongly dependent upon the imposed normal loads and displacement amplitudes. The F_t/F_n curves exhibited different variation trends in different fretting running regimes. The fretting scars presented slight damage in partial slip regime. In mixed fretting regime, the trace of the plowing and plastic deformation flow can be observed on the fretting scars. The wear mechanism during this regime was the combination of the abrasive wear, oxidative wear and delamination accompanied with obvious plastic deformation. The detachment of particles and plowing traces were the main phenomena in slip regime. And, thicker debris layer covered the contact zone of the scar. The severe degradation in slip regime presented the main wear mechanisms of abrasive wear, oxidative wear and delamination.     

Performance and wear mechanisms of whisker-reinforced alumina, coated and uncoated PCBN tools when high-speed turning aged Inconel 718

Inconel 718, an efficient superalloy for energy and aerospace applications, is currently machined with cemented carbide tools at low speed (v _c?≈?60 m/min) due to its unfavorable mechanical and thermal properties. The article presents results of a study of superalloy machinability with whisker-reinforced alumina, uncoated and coated polycrystalline cubic boron nitride (PCBN) tools. Turning of age-hardened Inconel 718 (45 HRC) was done under high-speed machining conditions (v _c?=?250…350 m/min). Aspects of tool life, tool wear, and generated surface quality were studied. Application of uncoated PCBN tools resulted in surface quality and force level superior to other tool materials. Considerable sideflow of workpiece material was found to affect surface quality, especially for coated PCBN and ceramic tools. It was found that protective function of the coating, which increases the tool life up to 20 %, is limited only to low cutting speed range. EDX and AFM analyses suggested dominance of chemical and abrasive wear mechanisms. EDX mapping of worn tools pointed absence of diffusional wear for PCBN tools and intensive degradation of whisker reinforcement in ceramic tools due to diffusion of Ni, Fe, and Cr.     

Effect of Cold Rolling on the Fretting Wear Behavior and Mechanism in Inconel 690 Alloy

The influence of cold rolling on the fretting wear behavior and mechanism of Inconel 690 alloy at 320?°C in air was studied. The wear volume and worn surface were obtained and analyzed using laser scanning confocal microscopy, electron back-scattering diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The grinding surface and strain distribution were also studied by electron back-scattering diffraction to analyze the mechanism of fretting damage. The results indicated that with an increase in cold rolling reduction, the microhardness was increased. However, the friction coefficient and wear volume first increased and then decreased. The characteristics of fretting areas changed from a gross slip regime to a partial slip regime. Accordingly, the damage mechanism in the gross slip regime was a combination of oxidative wear, abrasive wear, and delamination, whereas the damage mechanism in the partial slip regime was mainly adhesive wear.     

Carbide tool wear mechanism in turning of Inconel 718 superalloy

Wear surfaces of the cutting tools are analyzed to study the wear mechanism of cemented carbide tools in turning in Inconel 718 superalloys. SEM and EPMA analyses indicated that the wear of carbide tools during high speed turning condition (V = 35 m min⁻¹) was caused by diffusion of elements (Ni or Fe) in workpiece into tool's binder (Co) by a grain boundary diffusion mechanism. This action weakened the bonding strength between carbide particles (WC, TiC, TaC) and the binder (Co). The carbide particles were then detached out of the cemented carbide tool by high flow stresses. The proposed grain boundary diffusion mechanism is also confirmed by theoretical analysis.     

Fretting wear characteristics of cold gas-dynamic sprayed aluminum alloys

Process selection for repair of mechanical components due to wear and corrosion, e.g. damage of aluminum casting housings of fuel injection systems, is based on cost and response time factors, provided that the mechanical performance is maintained within acceptable limits. One of the promising and emerging repair technologies is Cold Gas-Dynamic Spray (CGDS) coating, where a high-pressure gas propels fine powder particles to very high velocities to produce surface coating. It is essential to identify the optimum process conditions and powder composition to produce repaired surfaces with tribological properties close to those of the originally manufactured part (without coating). The objective of this work is to compare the dynamic friction and fretting wear properties of the repaired surfaces using various types of coating composition and spraying techniques. Eight types of CGDS coatings, applied to AMS 4260 aluminum specimens, were fretted against 440C stainless steel specimens at low and high nominal loads to assess their fretting wear resistance, dynamic friction properties and damping capacity. The optimum coating composition and process conditions were identified. In comparison to the uncoated specimen, this optimum coating offered tribological characteristics close to the uncoated material and even better dynamic friction properties.     

Fretting Wear Behavior and Mechanism of Inconel 690 Alloy Related to the Displacement Amplitude

Fretting wear tests on Inconel 690 alloy were carried out at different displacement amplitudes. The results indicated that with an increase in displacement amplitude, the ratio of tangential force to normal load and wear volume increased. The fretting mode gradually transformed from mostly stick, mixed stick–slip, to full sliding, showing the competition of fretting-induced fatigue cracking and fretting-induced wear. There was a gradient plastic strain created by fretting, which resulted in the formation of a nanocrystalline tribologically transformed structure (TTS) and plastic deformation layers. The plastic strain in the plastic deformation layer gradually increased with an increase in displacement amplitude.     

Effect of cutting speed on cutting forces and wear mechanisms in high-speed face milling of Inconel 718 with Sialon ceramic tools

In this paper, a series of milling tests were carried out in order to identify the effects of cutting speed on cutting forces and tool wear when high-speed face milling Inconel 718 with Sialon ceramic tools. Both down-milling and up-milling operations were conducted. The cutting forces, tool wear morphologies, and the tool failure mechanisms in a wide range of cutting speeds (600–3,000 m/min) were discussed. Results showed that the resultant cutting forces firstly decrease and then increase with the increase of cutting speed. Under relatively lower cutting speeds (600 and 1,000 m/min), the dominant wear patterns is notching. Further increasing the speed to more than 1,400 m/min, the notching decreases a lot and flank wear becomes the dominant wear pattern. In general, at the same cutting speed, flaking on the rake face and notching on the flank face are more serious in down-milling operation than that in up-milling operation with the same metal removal volume. However, the surface roughness values for down-milling are lower than that for up-milling.