Thesis
The influence of microstructural condition and applied load on the tribological response of ferrous alloys in sliding
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2022
- Thesis identifier
- T16383
- Person Identifier (Local)
- 201888981
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- The wear of ferrous alloys is an important context in mechanical engineering. There are moving parts in nearly every mechanical system, and this therefore means that components must experience contact. This contact is inevitably accompanied by wear, and manifests through the loss of material and changes in geometry. Engineers seek to understand the way in which materials wear to extend component lifespans, reduce maintenance frequency, and improve user safety. The wear of materials is dependent on many factors, and is not an innate property such as strength. A particular alloy can exhibit acceptable wear resistance in one context andunfavourable resistance in another. Volume losses are instead dependent on the material properties, testing variables, and environmental conditions, which together make up the tribosystem. Only through investigation of the complete tribosystem can general wear predictions and characterisations be made. This thesis seeks to improve the state-of-the-art of ferrous tribology, with an aim of investigating the potential for life extension of mechanical components, and to push the current mechanistic understanding of how ferrous alloys wear.The tribological response of various ferrous alloys has been investigated herein through pin-on-disc sliding wear tests under various conditions. A number of materials are examined, ranging from cast iron to alloy steels to stainless steels. Four novel experimental chapters investigate different sets of variables, their subsequenteffect on the tribosystem, and present the results, discussions, and key conclusions of the thesis. Apart from the wide variety of materials tested, other variables investigated include the applied load, microstructural condition, and immersion media. The first experimental chapter compares the sliding wear resistance of seven alloysunder the same load in the dry regime. The resultant volume losses highlight the significance of beneficial oxidative wear in such scenarios, where the alloys steel and cast iron outperformed the stainless steels due to the formation of protective oxide shields. The second experimental chapter centres on tribocorrosion, featuring the sliding wear of grey cast iron, AISI 4330 alloy steel, and 15-5PH stainless steel under three applied loads in the dry regime and while submerged in NaCl solution. It was found that in the dry regime, the alloy steel outperformed the stainless steel for all three loads due to the ease of protective oxide formation, whereas this ranking was inverted in the NaCl regime. The third experimental chapter focusses on the microstructural evolution and slidingwear response of grey cast iron when subjected to spheroidising annealing heat treatments. At 6kg applied load, a non-linear transition occurred for the ten-day and fifteen-day samples, causing a significant increase in volume losses. This was attributed to the destruction of the cast iron surface integrity, causing significant deformation and resulting in severe wear. The fourth experimental chapter examines grey cast iron in the quenched and tempered condition. The harder samples tempered at 400°C experienced higher volume losses than those tempered at 500°C due to experiencing brittle fracture, whereas the softer samples tempered at 500°C were able to slightly deform and therefore avoid these brittle tendencies. The key findings of this thesis elucidate the macro and micro damage mechanisms of (primarily) ferrous alloys in sliding applications. The conclusions drawn are therefore practical, and of value in the engineering industry where refinement and optimisation are always sought.
- Advisor / supervisor
- Toumpis, Athanasios
- Galloway, Alexander
- Resource Type
- DOI
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PDF of thesis T16383 | 2022-10-26 | Public | Download |