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The purpose of this work was to study effects of different grain size distributions on fretting wear behavior of a low carbon steel flat specimen against a bearing steel ball. The grain structure of the low carbon steel was varied to produce a gradient microstructure consisting of fine grains at the surface and coarse grains in the interior. The novel method of surface treatment involved a multi-step...
The large deformations occurring in the surface layer of rail heads strongly influence the material behavior. Cracks typically develop from this critical region. However, conventional material testing of this layer is not possible due to the large gradients. A method for obtaining a similar material through predeformation is therefore investigated. Subsequent analyses of the obtained material can...
In this work, TiB2 particulate reinforced copper matrix composites were fabricated by casting method, based on in situ precipitation reaction between B and Ti elements to form TiB2 particles in molten copper. The microstructures of the Cu-TiB2 composites were characterized using SEM and TEM. The results show that TiB2 particles are successfully formed in the copper matrix and the interfaces between...
Mill roller shells are amongst the most important manufacturing-line elements in the sugar production process. They are carefully designed according to many surface criteria amongst which wear resistance is the most important. To increase the life of the mill roller shells, the resistance of the surface to failure by abrasion should be increased. In this investigation, a series of sixty-six cast iron...
Wear damage of Alloy 690TT in partial and gross slip fretting regimes at 320°C was investigated. The obtained fretting regimes were controlled by modifying the displacement amplitude. In partial slip regime, adhesive wear and fatigue crack were the main wear mechanisms. The nanostructured tribological transformed structure (TTS) formed due to incomplete dynamic recrystallization (DRX) with existence...
Wear and friction properties depend on many parameters such as normal load and material hardness. However, coupled contributions of microstructure and abrasive particle size are less investigated. A contribution in this field is proposed with wear tests performed between a 35NCD16 steel and abrasive silicon carbide grains ranging from 35µm to 200µm under different normal loads (50–110N). To vary hardness...
Polymeric materials generally suffer from a low resistance to various types of surface mechanical damage, among which scratch is a prominent example. While several attempts have been made to assess the scratch resistance and its relationship with the bulk mechanical properties in simple polymeric systems, the available research on the polymeric blends is scarce. This study attempts to fill this gap...
This work shows the successful application of a novel Fe85Cr4Mo8V2C1 (wt%) laser cladding wire material on a high-performance tool steel (1.2379, X155CrMo12-1) using a pulsed Nd:YAG laser system. Due to the high cooling rates during the welding process and appropriate laser parameters, a fine, homogeneous microstructure composed of martensite, austenite as well as VC- and Mo2C-type carbides was formed...
The technological evolution of more efficient natural gas-fuelled large bore engines aggravates the load situation within the engine and thus as well the tribological system valve spindle/seat ring. As a result of these changes, valve recession increases and component lifetime decreases, i.e. higher failure rates and more frequent service intervals. The tribological issues can be traced back to the...
In order to achieve the maximum benefit from the carbide-forming elements Ti and Nb, it is very important to have a better understanding of the strengthening mechanism of the two carbide-forming elements in the hardfacing alloy.The Fe-Cr13-C-Nb hardfacing alloy with and without Ti addition were deposited respectively on carbon steel substrates by shielded metal arc welding. The carbide-forming elements...
Microstructure evolution in polycrystalline metals, which undergo sliding contact, takes place by dislocation activity, followed by dislocation pile-up, formation of low-angle grain boundaries and consolidation of those low-angle grain boundaries as nanocrystalline grains, thus resulting in grain refinement. In dry contacts or boundary lubrication, this plasticity dominated process occurs in competition...
Laser alloying with boron and solid lubricants (CaF2 or BaF2) was used in order to produce the self–lubricating layers on 100CrMnSi6–4 bearing steel. The surface of the base material was coated with a paste consisting of alloying material blended with a diluted polyvinyl alcohol solution. Then, this surface was re-melted by the laser beam using TRUMPF TLF 2600 Turbo CO2 laser. The produced layer consisted...
Cryogenic treatment is an effective process to enhance the wear resistance of work pieces. Influences of cryogenic temperature, holding time and cooling rate on high-temperature wear behavior of M2 steel were studied, using a computerized ball-on-disc wear tester (HT1000). The results of the experimental tests showed that lowering the cryogenic temperature and prolonging the holding time, the wear...
In the literature many researchers have tried to correlate the (dry) abrasion resistance of steels to their standard mechanical properties as determined in simple tensile and hardness testing. However, many unclear or even conflicting correlations have been reported, in part due to small data sets being used, different testing methods and relatively simple data processing techniques. In the present...
Head Check is a major rolling contact fatigue (RCF) defect initiated after cyclic wheel/rail contacts by severe plastic deformation of the rail head surface. A field analysis campaign has been conducted on a site affected by Head Checking. The aim of this study is to increase understanding of the relationship between RCF cracking and plastic deformation of the pearlitic microstructure. Investigations...
In the last years several consumables which deposit hard nanostructured iron-based alloys with high resistance to abrasive wear have been developed. The microstructure of the weld metal usually shows variations with the welding procedure, particularly related to the heat input, number of layers and shielding gas type. The purpose of this work was to study the microstructural evolution and wear resistance...
The tribological behavior of polished and lapped 56NiMoCrV7 and Ck45 disks with lubrication was studied to link the impact of initial near-surface microstructure to the running-in behavior of the systems. The tests were performed using a pin-on-disk tribometer with radionuclide technique to resolve ultra-low wear rates. For the running-in different stressing regimes were applied. Whereas the lapped...
Mine hoists for medium depth and deep mines in China rely on friction hoists. Proper function of the equipment involves controlled frictional contact between a rope and a lining. While there has been a lot of empirical testing of friction hoist materials, studies of the effects of their microstructure and basic properties on friction and wear have largely been neglected. Three commercial grade linings...
Protective coatings for high temperature applications have to exhibit good oxidation resistance and microstructure stability. The effective protection of parts with hardfacing techniques depends on the impact of the substrate on the deposited alloy, typically assessed by dilution. This investigation aims to evaluate the effect of dilution on microstructure and high temperature wear of NiCrSiBC coatings...
High alloy white cast iron materials (Ni-Hard 4/ASTM A532) are widely used in cement, concrete and mining industries due to high wear resistance. In this study, the effect of boron on the microstructure, mechanical properties and wear resistance in white cast iron containing different contents of boron was investigated. For this purpose, ferro-boron was used during cast that boron will occur with...
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