Transition of Mild Wear to Severe Wear in Oxidative Wear of H21 Steel

2008 ◽  
Vol 32 (2) ◽  
pp. 67-72 ◽  
Author(s):  
S. Q. Wang ◽  
M. X. Wei ◽  
F. Wang ◽  
X. H. Cui ◽  
C. Dong
Keyword(s):  
Oxidative Wear ◽  
Severe Wear ◽  
Mild Wear

Tribological behaviour of hypereutectic Al-Si automotive cylinder liner material under dry sliding wear condition in severe wear regime

2020 ◽  
pp. 135065012096461
Author(s):  
Ajith Kurian Baby ◽  
M Priyaranjan ◽  
K Deepak Lawrence ◽  
PK Rajendrakumar
Keyword(s):  
Surface Morphology ◽  
Wear Behaviour ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
Liner Material ◽  
Severe Wear ◽  
Mild Wear ◽  
The Matrix ◽  
Pin On Disk ◽  
Silicon Particles

Hypereutectic Al-Si alloys are used as material for the engine block and cylinder liners in automobiles. Wear behaviour of hypereutectic Al-Si alloy system changes significantly with applied normal load in both mild wear and severe wear regime. Significant improvement in wear resistance can be obtained by exposing silicon particles through the chemical etching process. For Al-25% Si alloys, most studies are reported in mild and ultra-mild wear regime. In the present work, the wear of exposed silicon particles with varying load and speed in severe wear regime was investigated under the unidirectional sliding condition and bi-directional sliding condition using a pin-on-disk tribometer (POD) and a linear reciprocating tribometer (LRT), respectively. Rapidly solidified and T6 heat-treated Al-25Si alloy was polished and etched using 5% NaOH solution to expose the silicon particles. Experiments were carried out with normal loads varying from 40 N to 120 N in dry sliding conditions. Sliding speeds of 0.8 m/s and 1.5 m/s were applied for each load in case of a pin on disk tribometer whereas, in an LRT, the sliding velocities were 0.2 m/s and 0.45 m/s respectively for each set of the load. The surface topography was measured by means of a 3-D optical profilometer, and surface morphology was analyzed using SEM images. It was observed that at higher loads, larger Si particles were fractured and pushed into the matrix. Fractured silicon particles, along with smaller particles, were embedded into the matrix, thereby increasing the silicon concentration in the wear region. The comparison of the experimental results of unidirectional and bi-directional sliding that reveal the change in surface morphology of silicon particles, the friction characteristics at the interface, variation of surface 3-D roughness parameters, the wear rate and wear mechanisms of Al-25% Si alloys are analyzed and reported in the study.

The dry wear of steels II. Interpretation and special features

1965 ◽  
Vol 257 (1077) ◽  
pp. 51-70 ◽  
Keyword(s):  
Oxide Film ◽  
Phase Change ◽  
Strain Hardening ◽  
Frictional Heating ◽  
Combined Effects ◽  
Phase Hardening ◽  
Special Effects ◽  
Severe Wear ◽  
Wear Rates ◽  
Mild Wear

The pattern of wear outlined in part I is interpreted in the light of further experiments which reveal that the change from severe wear to mild is governed by the hardness and state of oxidation of the surfaces. At light loads (< T 1) severe wear is inhibited by the combined effects of strain hardening and oxidation. At higher loads (> T 2) mild wear recurs primarily as a consequence of a change of phase induced by frictional heating. The hardness accompanying the phase change is great enough, initially, to suppress severe wear without the intervention of an oxide film. At loads immediately above T 2, however, the hardness tends to fall if rubbing is prolonged and oxidation is again essential to preserve the mild wear state. Sustained phase-hardening does not occur until a higher load, roughly coinciding with the T 3 transition, is attained and this finding has an important bearing on the influence of inert atmospheres. The onset of permanent hardening is not responsible for the divergent pin and ring wear rates at T 3, though the phenomena may be linked by the magnitude of the temperatures required to cause phase-hardening; the T 3 transition and the trend at higher loads have been identified as special effects associated with the thermal asymmetry of the rubbing system.

Influence of Mechanical and Chemical Factors on Transition Between Severe and Mild Wear in Saline Solution

1997 ◽  
Vol 119 (4) ◽  
pp. 619-625 ◽  
Author(s):  
H. Goto
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Content ◽  
Cathodic Protection ◽  
Saline Solution ◽  
Concentration Level ◽  
Applied Potential ◽  
Severe Wear ◽  
Saturated Condition ◽  
Mild Wear ◽  
Chemical Factors

Pin-on-disk wear tests of carbon steels in saline solution were carried out at high loads to study the effects of mechanical and chemical factors on the transition between severe and mild wear. The factors were load, presliding time, concentration of saline solution, dissolved oxygen content, and applied potential for cathodic protection. Severe wear and seizure appear at low concentration levels of saline solution and the transition takes place at a certain concentration level of saline solution. The concentration level for the transition is higher under argon-saturated condition than under air-saturated condition. Mild wear is predominant over the whole range of dissolved oxygen content from 0.5 to 18 ppm in 0.5 wt percent saline solution and the wear rate decreases with decreasing dissolved oxygen content. The mild wear occurs in the range from 2 to 18 ppm in 0.01 wt percent saline solution, whereas the wear mode moves to severe wear below 2 ppm. Mild wear predominates under incomplete cathodic protection between −0.50 and −0.80 V (versus Ag/AgCl in 0.5 wt percent saline solution. The applied potential for the transition from initial to steady wear is more negative under higher dissolved oxygen content condition. Complete severe wear occurs below −0.90 V (versus Ag/AgCl) with a risk of seizure.

Effect of Microstructure on Sliding Wear of Ca α-SiAlON Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 1253-1258 ◽  
Author(s):  
Zong Han Xie ◽  
Mark Hoffman ◽  
Robert J. Moon ◽  
P. R. Munroe ◽  
Yi Bing Cheng
Keyword(s):  
Wear Rate ◽  
Contact Pressure ◽  
Material Removal ◽  
Room Temperature ◽  
Oxidation Products ◽  
Wear Behaviour ◽  
Transgranular Fracture ◽  
Severe Wear ◽  
Pull Out ◽  
Mild Wear

The wear behaviour of Ca a-sialon ceramics of two distinct microstructures, fine equiaxed grains (EQ) and large elongated grains (EL), with the same chemical composition was investigated as a function of apparent contact pressure and sliding speed, using ball-on-disc type tribometers at room temperature and at 600°C. For room temperature tests, the EL microstructure exhibited a lower wear rate than EQ in the severe wear regime due to a greater resistance to large crack-induced material removal. As the apparent contact pressure decreased, mild wear appeared for both microstructures. The mechanism that dominated the material removal in EQ was grain pullout. In contrast, the controlling mechanism for EL was transgranular fracture. Therefore, EL had a lower wear rate than EQ in the mild wear regime. For wear tests at 600°C, crack-induced severe wear occurs in both EQ and EL samples for all contact pressures. EL had a slightly lower wear rate than EQ. Wear particles were generated on the wear track, but no tribofilm was observed and no oxidation products were detected. Wear models revealed that the grain aspect ratio plays a more important role than grain diameter in influencing the crack propagation during severe wear and grain pull-out during mild wear.

The formation of surface films at the transition between mild and severe metallic wear

1963 ◽  
Vol 273 (1355) ◽  
pp. 466-483 ◽  
Keyword(s):  
Surface Film ◽  
Surface Films ◽  
Surface Layers ◽  
Severe Wear ◽  
Wear Process ◽  
High Speeds ◽  
Mild Wear ◽  
Oxide Particles ◽  
Heavy Loads ◽  
Micro Analysis

The conditions of sliding have been found in which a transition occurs between the régimes of mild and severe wear for a leaded brass (60/40 brass containing 2% lead) sliding on hardened steel without lubrication. At light loads, low speeds, and low temperatures, mild wear begins when sufficient time is available to establish a protective surface film by oxidation; in addition, mild wear also occurs at heavy loads, high speeds and high temperatures because of an increase in the rate of oxidation. The topography and composition of the films generated on the brass during mild wear have been examined by reflexion electron microscopy and X-ray micro-analysis. The presence of a relatively large proportion of iron oxide in the surface layers, originating from the steel, increases their hardness and, in turn, causes wear of the steel itself. The variation of the rates of mild wear with load and speed is complex and, in contrast to the severe wear process, there is no unique mechanism of wear. It is concluded that mild wear of brass results from the combined effects of intermittent metal-to-metal contact, abrasion by oxide particles, and flaking of the oxide layers from the surface.

Paper 4: An Experimental Study of the Frictional Behaviour of Steels at Elevated Temperatures

1966 ◽  
Vol 181 (15) ◽  
pp. 1-10
Author(s):  
L. A. Mitchell ◽  
T. S. Crawford
Keyword(s):  
Experimental Study ◽  
Coefficient Of Friction ◽  
Elevated Temperatures ◽  
Oxide Films ◽  
Hardened Steel ◽  
Material Combination ◽  
Severe Wear ◽  
Mild Wear ◽  
The Coefficient Of Friction ◽  
Frictional Behaviour

Many investigators, by the manner of presentation of results, have implied that for any given material combination and atmosphere, the coefficient of friction is a function of temperature alone. Experiments are described which were designed to evaluate the importance of the sliding and temperature histories on the unlubricated sliding performance of steels at temperatures up to 500°C. Only for a hardened steel, when mild wear prevailed, was the specimen history unimportant, and, in this case, μ was virtually independent of temperature. With materials exhibiting severe wear, sliding produced changes in friction which were attributed to hardening of the surfaces and when the thickness of oxide films became comparable with the size of transferred particles, exposure to temperature could modify subsequent frictional behaviour.

Predicting Bearing Performance of Filled Teflon TFE Resins

1967 ◽  
Vol 89 (1) ◽  
pp. 182-186 ◽  
Author(s):  
R. B. Lewis
Keyword(s):  
Surface Temperature ◽  
Bearing Surface ◽  
Temperature Dependent ◽  
Wear Factor ◽  
Severe Wear ◽  
Wear Rates ◽  
Surface Temperatures ◽  
Mild Wear ◽  
New Evidence

The wear rates of filled compositions of Teflon can be reliably predicted using an experimentally determined wear factor if the bearing pressure, velocity, temperature, and geometry are known. New evidence confirms the wear rates are directly proportional to pressure and velocity in both the mild wear regime and the severe wear regime, although the wear factors are much higher in the severe regime. The transition from mild to severe wear is pressure and surface temperature dependent and coincides with (but is not adequately described by) PV limit. An application factor is proposed to relate bearing surface temperatures to PV and geometry.

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