Wear

Ductile iron can acquire enhanced thermal and mechanical properties from austempering heat treatment. The present study aims to identify the function of different cutting parameters affecting machinability and to quantify its effects. Turning was performed to test machinability according to the ISO3685-1993 (E) standard. After austenitizing at 900 °C for 90 min, austempered ductile iron (ADI) specimens were quenched in a salt bath at 380 °C for 90 min. The cutting force signals along three directions were measured in real time, whereas flank wear and surface roughness were measured offline. For the cutting parameters, the cutting speed and depth of cut were varied, but the feed rate was kept constant. In the flank wear tests, machining length was corresponded to tool life. In addition, in order to find out the effect of cutting parameters on surface roughness (Ra), tangential force (Ft), and flank wear (VB) during turning, response surface methodology (RSM) was utilized by using exp...

The present study concerns laser surface alloying with silicon of mild steel substrate using a high-power continuous wave CO2 laser with an objective to improve wear resistance. The effect of surface remelting using nitrogen as shrouding environment (with and without graphite coating) on microhardness and wear resistance has also been evaluated. Laser surface alloying leads to formation of a defect free microstructure consisting of iron silicides in laser surface alloyed mild steel with silicon and a combination of silicides and nitrides when remelted in nitrogen. Carbon deposition prior to remelting leads to presence of a few martensite in the microstructure. A significant improvement in microhardness is achieved by laser surface alloying and remelting to a maximum of 800 VHN when silicon alloyed surface is melted using nitrogen shroud with carbon coating. A detailed wear study (against diamond) showed that a significant improvement in wear resistance is obtained with a maximum improvement when remelted in nitrogen atmosphere followed by carbon coating.

The impact of thermal barrier coatings by hard projectiles at high temperature has been analyzed. Three different domains have been explored: each differentiated by particle size, velocity, temperature and TBC composition. Domain I applies when the projectile creates deeply penetrating plastic/densification zones. In this case, short time elastic effects are relatively unimportant. The response is dominated by stresses that arise

In this project, the alternating torsion fatigue test was carried out to investigate the effect of the nitrided case produced by gas and plasma nitriding processes on the fatigue endurance of the JIS SACM 645 steel. The surface layers of the nitrided specimens exhibited hardness profiles in the range between 1000–1100HV0.1, and the white layer of the nitrided specimen was consisted of Fe3N and Fe4N. Wear test result indicated that the mass loss of JIS SACM 645 steel was greatly improved by nitriding processes. From the mass loss data, the wear resistance of the steel was significantly influenced by nitriding time. The fatigue strength of the 35C-GN48 nitrided specimen rose 51.9% to 632 MPa, which was the maximum fatigue strength in this study.

The main cause of damage to oil and gas equipment is wear. This paper proves that
the principal wear mechanism is abrasive and shock-abrasive wear; and analyzes
materials test methods and techniques for wear rate identification. The author considers
standardized and non-standardized methods and establishes that despite a large
number of materials test methods, we don’t have a unique one for adequate assessment
of wear resistance in metals. It is concluded that selection of test methods depends on
working conditions of the equipment and use of different types of wear to assess
resistance of metals.

We describe several examples where we use cross-correlation functions to quantify the similarity of 2D surface profiles or of 3D areal surface topography images. The applications have included (1) the manufacture of standard reference material (SRM) bullets and casings, (2) methods to assess whether bullets or casings have been fired by the same firearm, and (3) research to quantify similarities or differences between profiles of the same surface measured by different techniques or between a master surface and its replicas. The cross-correlation maximum is the functional parameter used to quantify similarity. A second parameter, called the relative profile (2D) difference or relative areal topography (3D) difference, may also be used to quantify differences and to recognize the ambiguous condition when two results have different vertical (z-) scales but identical shapes. Most of these examples have been applied in support of ballistics inspection methods in crime labs, but the methods are generally useful for estimating the accuracy of surface replication techniques or the ability of different surface topography instruments to measure the same surface and provide the same result. The instruments used in these studies were a stylus instrument and a Nipkow-disk type confocal microscope. Cross-correlation functions may also be used to assess differences resulting from the use of different filters to modify the same surface profile or topography image.

In this paper the friction and sliding wear of WC–Co cemented carbides are studied. Friction and wear tests were carried out using six different WC–Co alloys (Co ranging from 6 to 20wt.%) under unlubricated conditions against steel (0.45wt.% C) disk. Tests were performed at sliding velocity of 2.2ms−1 and normal load of 40 and 180N. Sliding wear tests were carried

Among the light metals, Mg and its alloys occupy a prominent position due to its low density, excellent machinability, and high specific strength. However, a relatively poor resistance to corrosion and wear are serious impediments against wider application of Mg alloys. In the present study, an attempt was made to enhance pitting corrosion resistance and microhardness of a commercial Mg alloy, MEZ (Zn 0.5%, Mn 0.1%, Zr 0.1%, rare earth elements 2%, Mg remaining percentage) by laser surface melting. The study included a detailed characterization of laser surface melted zone in terms of microstructure, phase analysis and its correlation with process parameters to optimize the laser processing routine. Mechanical properties like microhardness, wear, and electrochemical properties like pitting corrosion resistance of the surface melted layer were studied in detail. Microhardness of the laser surface melted layer was improved to 85–100 VHN as compared to 35 VHN of the as-received MEZ. Pitting corrosion resistance of the laser surface melted MEZ, significantly improved in a 3.56 wt.% NaCl solution because of grain refinement and redistribution of the intermetallic phases following rapid quenching associated with the process. The wear resistance of laser surface melted layer was also improved as compared to as-received MEZ.

Using a transparent tool entrapment, compression and eventual escape of liquid lubricant in surface pockets is observed in plane strip drawing. The two mechanisms of lubricant escape, Micro Plasto HydroDynamic and Hydrostatic Lubrication (MPHDL and MPHSL), are observed and quantified experimentally with varying viscosity, speed, reduction, workpiece material, back tension and friction. The mechanisms are influenced by all these parameters in an explicable way. Theoretical models of the escape mechanisms are established combining continuum mechanic analyses of the die pressure distribution with a fluid mechanic analysis of the lubricant escape. Oscillations in the drawing force are caused by the local escape of lubricant.

TBM excavation has become increasingly common, despite the fact that precise evaluation of certain risks has not kept pace with the use of these machines. One of the risks easily overlooked by Engineer and Contractor alike are the effects of abrasive ground on the costs and schedule of a given project. The impacts of worn and damaged TBM cutterheads have been observed on hundreds of tunnel projects around the world. It would appear that a reliable prognosis of the abrasiveness of ground on a project would be of great importance for designers, clients and contractors alike. Several well acknowledged test and prognosis methods already exist for rock; however, there is only very limited knowledge available to describe the abrasiveness of soil and its impact on wear on soft ground TBMs. This three-part article examines existing approaches to the problem and suggests a new approach based on a current project undergoing design. Defining wear For the purposes of the following discussion it...

The minimum requirements to verify tooth wear results are a three quadrant spherical surface of a molar tooth to be common area, and the fit of the common area needs to be less than 10 μm, to achieve the sensitivity of wear measurement up to the 100 μm level on the occlusal ...

The objective of this experimental study was to determine the wear resistance of moldboard plowshares produced from 30MnB5 steel that were treated with different martempering conditions. The microstructures, the hardness distribution, and the wear behavior of the martempered 30MnB5 steel were determined and compared with conventionally heat-treated samples in laboratory conditions. The wear losses of all martempered samples were less than that of the conventionally heat-treated samples in laboratory conditions, especially at the end of a longer-term wear experiment. The martempering process in which the steel was austenized at 960°C for 35 min, held at 350°C for 10 s in a salt bath, and then cooled in air produced the best results for decreasing wear loss in laboratory conditions. The martempering treatment that resulted in the lowest wear weight loss in pin-on-disc tests was selected for further testing in field conditions. The field used for the experiment was flat and free of crop residue with a uniformly dispersed soil type (sandy and sandy loam). A reversible plow was used to measure the wear. The abrasive wear losses were determined by measuring the plowshare's weight and dimensions before and after tillage. By achieving a more uniform hardness distribution, the lath-type martensitic and bainitic microstructure of the martempered plowshares significantly increased their wear resistance. The martempering process decreased the wear weight loss by 40.8% and the wear dimension loss by 38.5% compared to conventionally heat-treated plowshares in field conditions.


Keywords: Martempering, abrasive wear, Plowshare, Soil tillage, Wear, boron-alloyed steels, carbo-martempering