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High chromium white cast irons are extremely abrasion resistant materials due primarily to their high carbide content. In the columnar zone of cast structures, eutectic carbides grow parallel to the direction of heat flow, forming a highly anisotropic morphology. In this US Bureau of Mines investigation, specimens taken from the columnar zone of these castings were tested utilizing a pin abrasion...
Numerous fields of aircraft and engine construction are concerned by wear damage due to erosion. An original tribometer for the study of erosion is described. The basis of the study undertaken here is the notion of conceptual parameters that are the internal variables of the simulation device; it was compulsory to define and to control these variables during experimental.We have then examined the...
Martensite spheroidal cast iron is an abrasion-resistant material of superior toughness to white case irons. In order to assess the effects of matrix and graphite phases on the wear performance of the iron, abrasion tests were carried out under both two-body (pin-on-disc) and three-body impact conditions. The matrices involved in the tests included martensite, martensite with increased retained austenite,...
The response of three commercial weld-hardfacing alloys to erosive wear has been studied. These were high chromium white cast irons, deposited by an open-arc welding process, widely used in the mineral processing and steelmaking industries for wear protection. Erosion tests were carried out with quartz sand, silicon carbide grit and blast furnace sinter of two different sizes, at a velocity of 40...
This paper presents the results obtained and the deductions made from a series of wear tests involving sub-zero chilled (using liquid nitrogen) cast iron containing 1.5% Cu, and chromium contents ranging from 0.0% to 0.2%. By using copper chills of different thicknesses, the effect of wear resistance of varying the chill rate was also examined. The wear tests were carried out using a modified pin-on-disk...
In this study the wear mechanisms of ceramic/cast iron and ceramic/ceramic couples and the relationship of these mechanisms with the tested materials' microstructure were analysed. Wear mechanisms were identified in this particular type of testing and a correlation between material testing parameters and its wear behaviour was established. The interaction between the various wear mechanisms of wear...
Hexagonal boron nitride (BN) has a graphite-like lamellar structure, but has been considered less effective than other solid lubricants except for high-temperature applications. The present paper describes a series of sliding experiments which show somewhat curious behavior of BN when added to lubricating oil, and discusses their results by comparing with the results of observation and analysis of...
An extensive study has been carried out on grey cast iron (BS 1452) in liquid erosion and liquid-solid erosion conditions in which weight loss tests have been used in conjunction with electrochemical measurements and microscopy. The study has revealed interesting effects of the impingement velocity in solid-free conditions and of solids loading at constant velocity. This experimental approach has...
The influence of titanium additions up to 0.38% and heat treatment on the abrasion resistance of a commercial 15% Cr-3% Mo white cast iron were examined. The wear resistance of as-cast commercial alloy was improved about 30% by addition of 0.38% titanium after austenising at 1050 o C for 6h and quenching in air. Tempering of quenched alloys at 250 o C for 6h yielded a decrease in hardness...
The sliding wear resistance of a A30 type grey cast iron against AISI 52100 type steel was measured within a load range of 0.3-50.0N, and a sliding speed range of 0.2-3.0m/s using a block-on-ring wear machine. The wear rates and the surface temperatures were measured as a function of loading conditions. A wear map was constructed to summarize the measured wear rates and mechanisms that control the...
Recent attention to the improvement of line-haul truck brake effectiveness, to compensate for lowered aerodynamic drag and to increase road safety, has prompted the US Department of Energy to support several projects aimed at the development of lightweight, high-performance friction materials. Using a specially designed, sub-scale disc brake testing system, a series of experiments was conducted to...
Frictional stability and wear resistance are key performance requirements for heavy truck brake linings. Lining-counterface friction affects the rate of vehicle deceleration, but wear also affects stopping characteristics because uneven or high wear can alter the contact geometry of the lining, change the pattern of frictional heat generation, and degrade the response of the braking system. Inertia...
This study pertains to the examination of sliding wear behaviour of a gray cast iron over a range of sliding speeds and applied pressures in dry and (oil and oil plus graphite) lubricated conditions. Wear properties characterized were wear rate and frictional heating. The cast iron revealed various forms and sizes of graphite particles in a matrix of pearlite and limited quantity of free ferrite....
Wear particles are produced as a result of interaction of two surfaces in mechanical systems. After extracting and separating particles by different techniques (filtration, ferrography …), their morphology, which is a function of the condition of tribological system (tribosystem), can be related directly to the wear process. In order to understand wear mechanisms, it is interesting to study the relationship...
This work presents a study on the influence of residual stresses on the contact fatigue resistance of a gray cast iron and a ductile iron. Contact fatigue tests were conducted in a ball on washer machine. The specimens were taken from bars of gray and ductile iron produced by continuous casting. After machining, specimens of both materials were quenched and tempered to the same matrix hardness, of...
To clarify the dry friction and wear characteristics of several kinds of cast irons under the conditions of high sliding speed and high contact pressure was intended here. The friction tests with a cast iron pin sliding on a mild steel disk were carried out by using the originally designed pin-on-disk type test rig. Five kinds of cast irons which had difference in the structure, the component, the...
This work aims to study the influence of the chemical composition and the microstructure of gray cast iron on wear of heavy duty diesel engines cylinder liners. Two kinds of lamellar gray cast iron are studied: a classical gray cast iron and a micro-alloyed gray cast iron. Polished samples are tested.Reciprocating friction tests with the configuration steel ball against a flat sample, extracted from...
The aim of this article is to find correlations between the characteristics of the wear particles, the coefficients of friction and the wear rates in order to determine wear mechanisms. In the air compressors, piston rings are made of polytetrafluoroethylene (PTFE) but its wear rate is very high and it must be reinforced. This work is devoted to the influence of temperature with three types of PTFE...
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 3 C carbides (cementite). Pin-abrasion tests were carried out using fixed alumina abrasive grains at different loads: 1, 2, 4.6 and 10N. The wear surface and the abrasive paper were examined by scanning...
A finer microstructure generally helps to increase the wear resistance of materials. It was reported that Ti could act as an inoculant to generate fine microstructure for white cast iron, one of widely used in industrial materials. To confirm this, we investigated influences of Ti addition (up to 6wt.%) on microstructure of a hypereutectic high chromium cast iron (Fe–25wt.%Cr–4wt.%C). Ingot samples...
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