Dry wear behavior and mild-to-severe wear transition in an Mg-Gd-Y-Zr alloy

2021 ◽  
Author(s):  
Y B Wang ◽  
Liang Li ◽  
Jian An
Keyword(s):  
Wear Behavior ◽  
Severe Wear ◽  
Wear Transition ◽  
Zr Alloy

scholarly journals Dry Sliding Wear Behavior and Mild–Severe Wear Transition of Mg97Zn1Y2 Alloy at Elevated Temperatures

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1735 ◽  
Author(s):  
Liang Li ◽  
Jihe Feng ◽  
Ce Liang ◽  
Jian An
Keyword(s):  
Test Temperature ◽  
Sliding Wear ◽  
Elevated Temperatures ◽  
Wear Behavior ◽  
Hardness Measurement ◽  
Dry Sliding Wear ◽  
Dry Sliding ◽  
Softening Effect ◽  
Severe Wear ◽  
Wear Transition

Dry sliding wear behavior of Mg97Zn1Y2 alloy was investigated at test temperatures of 50–200 °C under three sliding speeds of 0.8 m/s, 3.0 m/s and 4.0 m/s. The wear mechanisms in mild and severe wear regimes were identified by examination of morphologies and compositions of worn surfaces using scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS), and from which wear transition maps under different sliding speeds were constructed on rectangular coordinate systems with applied load versus test temperature axes. It is found that under each sliding speed condition, mild–severe transition load decreases almost linearly within the test temperature range of 50 °C to 200 °C. Microstructure observation and hardness measurement in subsurfaces identify that the softening effect generating form dynamic crystallization (DRX) is the dominant mechanism for the mild–severe wear transition at elevated temperatures. The mild–severe wear transition at 50–200 °C follows the contact surface DRX temperature criterion, and the transition loads can be well evaluated using the criterion.

Wear Behavior and Microstructural Evolution during Dry Sliding Wear of AZ51 Magnesium Alloy

2014 ◽  
Vol 1061-1062 ◽  
pp. 674-678
Author(s):  
Yuan Bo Wang ◽  
Teng Fei Su ◽  
Ming Liang Yin ◽  
Xue Han ◽  
Xin Ying Li ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Microstructural Evolution ◽  
Wear Behavior ◽  
Thermal Softening ◽  
Surface Melting ◽  
Dry Sliding Wear ◽  
Near Surface ◽  
Severe Wear ◽  
Wear Transition ◽  
Subsurface Microstructure

Wear behavior of AZ51 magnesium alloy was studied using a pin-on-disc type wear apparatus at 20-360 N and 0.785 m/s. Wear mechanisms were determined using scanning electron microscope (SEM), including abrasion, oxidation, delamination, thermal softening and surface melting. Microstructural evolution, plastic deformation and microhardness in the subsurfaces were examined with optical microscope and hardness tester before and after mild to severe wear transition. The subsurface microstructure experienced deformation, dynamic recrystallization (DRX) and surface melting successively with increasing load. These changes in subsurface microstructure result in strain hardening and thermally-activated softening in the near-surface layers. The thermal softening originating from DRX and surface melting in subsurface is responsible for the mild to severe wear transition.

scholarly journals Masking Effect of LPSO Structure Phase on Wear Transition in Mg97Zn1Y2 Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1857
Author(s):  
Fujun Tao ◽  
Hongfei Duan ◽  
Lijun Zhao ◽  
Jian An
Keyword(s):  
Wear Rate ◽  
Elevated Temperatures ◽  
Wear Behavior ◽  
Testing Machine ◽  
Masking Effect ◽  
Enhancement Effect ◽  
Severe Wear ◽  
Lpso Structure ◽  
Structure Phase ◽  
Wear Transition

Room- and elevated-temperature wear tests were conducted using a pin-on-disk testing machine to study wear behavior of Mg97Zn1Y2 alloy and role of long-period-stacking-ordered (LPSO) structure phase in mild–severe wear transition (SWT). Variation of wear rate exhibited a three-stage characteristic with load at various test temperatures, i.e., a gradual increasing stage, a slightly higher plateau stage, and a rapid rising stage. The wear mechanisms in the three stages were identified using scanning electron microscope (SEM), from which the first stage was confirmed as mild wear, and the other two stages were verified as severe wear. The interdendritic LPSO structure phase was elongated into strips along the sliding direction with Mg matrix deformation in the subsurface, plate-like LPSO structure phase precipitated at elevated temperatures of 150 and 200 °C. The fiber enhancement effect and precipitation effect of LPSO structure phase resulted in a little difference in wear rate between the first and second stages, i.e., a masking effect on SWT. Microstructure and microhardness were examined in the subsurfaces, from which the mechanism for SWT was confirmed to be dynamic recrystallization (DRX) softening. There is an apparently linear correlation between the critical load for SWT and test temperature, indicating that SWT is governed by a common critical DRX temperature.

An Investigation on Transition Between Mild and Severe Wear in Mg–5Al–0.8Zn Magnesium Alloy Using Recrystallization Kinetics Modeling

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
C. Liang ◽  
T. F. Su ◽  
Y. B. Wang ◽  
X. Han ◽  
M. L. Yin ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Wear Behavior ◽  
Optical Microscope ◽  
Load Range ◽  
Sliding Speed ◽  
Severe Wear ◽  
Hardness Tester ◽  
Before And After ◽  
Pin On Disk ◽  
Wear Transition

Wear behavior of Mg–5Al–0.8Zn alloy was studied using a pin-on-disk type wear apparatus within a load range of 20–380 N and a sliding speed range of 0.1–4.0 m/s. Analyzes on morphology and chemical composition of worn surfaces were undertaken using scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS) for determination type of wear mechanism. Investigations on microstructure, plastic strain, and hardness in subsurfaces were carried out using optical microscope and hardness tester for understanding changes in the microstructure and hardness before and after mild to severe wear transition. The subsurface microstructure beneath the worn surface was subjected to a large plastic strain, and experienced strain hardening, dynamic recrystallization (DRX), and melting successively with increasing load or sliding speed. The transition between mild and severe wear was controlled by microstructure transformation from a strain-hardened into a thermal soften DRX microstructure in subsurface. A contact surface DRX temperature criterion is proposed for prediction of transition between mild and severe wear in Mg–5Al–0.8Zn alloy. The mild to severe wear transition loads were predicted under various sliding speeds using DRX kinetics. The validity of the proposed method for prediction of transition between mild and severe wear is also verified in AZ31 and AZ61 alloys.

scholarly journals Investigation of the Wear Behavior of Surface Welding AZ91 and AZ91+Gd Alloys under Variable Loading Conditions

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 554
Author(s):  
Qingqiang Chen ◽  
Yalei Yu ◽  
Jie Sun ◽  
Cainian Jing ◽  
Yanhua Zhao ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Magnesium Alloy ◽  
Wear Rate ◽  
Wear Mechanism ◽  
Sliding Friction ◽  
Wear Behavior ◽  
Az91 Alloy ◽  
Severe Wear ◽  
Surface Welding ◽  
Wear Transition

Adding rare earth elements to magnesium alloys is an effective way to improve their wear resistance. However, the effect achieved is closely related to the friction condition. In this paper, two different types of welding wires, AZ91 magnesium alloy and AZ91 + gadolinium (Gd), were used for surface welding. Dry sliding friction and wear experiments were performed on the surfacing alloys using the pin-on-disc test. The effects of Gd addition on the wear resistance and wear mechanism of the alloy were systematically studied under low to high loads. The results show that as the load increases, the friction coefficient of the surfacing AZ91 alloy gradually decreases as the wear rate increases. A mild–severe wear transition occurred at 100 N. The addition of Gd only slightly increased the wear rate under a load of 15 N. The wear rate was significantly decreased with loads in the range of 30 to 100 N and mild–severe wear transition was avoided. The influence of both Gd addition and load on the wear mechanism were considered. The overall wear resistance of the surfacing magnesium alloy was determined.

Wear and Compatibility Behavior of Liquid Metal Bearing Materials

1967 ◽  
Vol 89 (4) ◽  
pp. 466-472
Author(s):  
M. J. Wallace
Keyword(s):  
Power Plants ◽  
Wear Behavior ◽  
Development Program ◽  
Rotating Disk ◽  
Rankine Cycle ◽  
Cemented Carbides ◽  
Cycle Space ◽  
Bearing Materials ◽  
And Performance ◽  
Zr Alloy

The wear and compatibility characteristics of selected bearing materials, including surface coatings and cemented refractory carbides were investigated in support of a pump development program for advanced Rankine cycle space power plants employing high temperature lithium and NaK. Compatibility of candidate materials with 1100-deg lithium in Cb-1 Zr alloy was studied in tilting capsule tests for durations to 7000 hr. The wear behavior of material combinations was evaluated with a rotating disk-static shoe assembly in lithium and NaK to 1000 deg. The best compatibility and wear characteristics were exhibited by high density molybdenum cemented carbides. Carburized Cb-1 Zr alloy wear resistance was inconsistent but, under the best conditions, was nearly equivalent to that of the cemented carbides. Plasma sprayed coatings of tungsten carbide and WC-Co gave encouraging results in NaK, but additional development of the coating process appeared necessary to assure reliable control of adhesion and performance.

Wear Behavior of Laser Surface-Hardened Gray and Ductile Cast Irons: Part 1—Sliding Wear

1986 ◽  
Vol 108 (3) ◽  
pp. 326-333 ◽  
Author(s):  
P. A. Molian ◽  
Mark Baldwin
Keyword(s):  
Sliding Wear ◽  
Continuous Wave ◽  
Wear Behavior ◽  
Test System ◽  
Case Depth ◽  
Laser Surface ◽  
Dramatic Improvement ◽  
Cast Irons ◽  
Severe Wear ◽  
Depth Analysis

The influence of laser surface transformation hardening on the sliding wear characteristics and mechanisms of ASTM class-40 gray and 80-55-06 ductile cast irons was investigated. A 1.2 kw, continuous wave, CO2 gas laser was employed to scan the beam successively across the surfaces of cast irons to generate hardened and tempered layers with various case depths. A pin-on-disk wear test system was then used to study the wear behavior as functions of case depth, microstructure, hardness, and surface roughness. As expected, a dramatic improvement in resistance to scuffing and sliding wear was obtained. However, the most significant result was the occurrence of negligible oxidational wear for a load range that increased with an increase in case depth. Resistance to mild and severe wear, mild-to-severe wear transition load, and frictional heating were increased with an increase in case depth. Analysis of worn surfaces and wear debris revealed that negligible oxidational wear in laser-hardened irons is due to two mechanisms: oxidation and adhesion of oxide to the substrate. In contrast, the mild oxidational wear of untreated irons occurs through the formation of loose oxide debris. The mechanisms of severe wear were plastic deformation, delamination, and adhesion; the rate process was controlled by adhesion for laser hardened irons and delamination for untreated irons.

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