Podcast
Questions and Answers
What are the factors that influence diffusion in self-diffusion?
What are the factors that influence diffusion in self-diffusion?
What is the maximum solid solubility of carbon in ferrite?
What is the maximum solid solubility of carbon in ferrite?
0.022%
Pearlite is a type of microstructure in the heat treatment of ferrous alloys.
Pearlite is a type of microstructure in the heat treatment of ferrous alloys.
True
Aging is also known as __________ hardening.
Aging is also known as __________ hardening.
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Match the alloy heat treatment with its description:
Match the alloy heat treatment with its description:
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What is self-diffusion?
What is self-diffusion?
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Define hardenability of ferrous alloys.
Define hardenability of ferrous alloys.
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Match the following microstructures with their respective descriptions:
Match the following microstructures with their respective descriptions:
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What is the purpose of annealing in metalworking?
What is the purpose of annealing in metalworking?
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Study Notes
Self-Diffusion
- Self-diffusion is the process of atoms of one metal diffusing to the same metal
- Factors that influence diffusion are the diffusing species and temperature
Metal Alloys
- Alloys are composed of two or more chemical elements, at least one of which is a metal
- Most metals used in engineering applications are some form of alloy
Alloying
- Alloying consists of two basic forms: solid solution and inter-metallic compounds
The Iron-Carbon System
- Ferrite: a solid solution of body-centered cubic iron with a maximum solid solubility of 0.022% carbon at 727°C (1341°F)
- Ferrite is relatively soft and ductile, and is magnetic from room temperature to 768°C
- Austenite: has a solid solubility of up to 2.11% carbon at 1148°C
- Cementite: 100% iron carbide (Fe3C) with a carbon content of 6.67%, a hard and brittle inter-metallic compound
Heat Treatment of Ferrous Alloys (Microstructure)
- Pearlite
- Spheroidite
- Bainite
- Martensite
- Retained austenite
- Tempered martensite
Hardenability of Ferrous Alloys
- Hardenability is the capability of an alloy to be hardened by heat treatment
- It is a measure of the depth of hardness that can be obtained by heating and subsequent quenching
- The fluid used for quenching the heated alloy also affects hardenability
Heat Treatment of Non-Ferrous Alloys and Stainless Steel
- Solution treatment: heating the alloy to within the solid-solution phase and then cooling rapidly
- Precipitation hardening:
- Aging: a time and temperature dependent process, also known as age hardening
- Maraging: a precipitation-hardening treatment for a special group of high strength iron-base alloys, derived from martensite age hardening
Annealing
- Annealing is the restoration of a cold-worked or heat-treated metal or alloy to its original properties
- It increases ductility, reduces hardness and strength, or modifies the microstructure
- Annealing also relieves residual stresses in a manufactured part for improved machinability and dimensional stability
The Annealing Process
- Heating the workpiece to a specific range of temperature
- Holding it at that temperature for a period of time
- Cooling it slowly
Classifications of Annealing
- Process annealing: restoring ductility, part or all of which may have been exhausted by work hardening during cold working
- Stress-relief annealing: reducing or eliminating residual stresses
Self-Diffusion
- Self-diffusion is the process of atoms of one metal diffusing to the same metal
- Factors that influence diffusion are the diffusing species and temperature
Metal Alloys
- Alloys are composed of two or more chemical elements, at least one of which is a metal
- Most metals used in engineering applications are some form of alloy
Alloying
- Alloying consists of two basic forms: solid solution and inter-metallic compounds
The Iron-Carbon System
- Ferrite: a solid solution of body-centered cubic iron with a maximum solid solubility of 0.022% carbon at 727°C (1341°F)
- Ferrite is relatively soft and ductile, and is magnetic from room temperature to 768°C
- Austenite: has a solid solubility of up to 2.11% carbon at 1148°C
- Cementite: 100% iron carbide (Fe3C) with a carbon content of 6.67%, a hard and brittle inter-metallic compound
Heat Treatment of Ferrous Alloys (Microstructure)
- Pearlite
- Spheroidite
- Bainite
- Martensite
- Retained austenite
- Tempered martensite
Hardenability of Ferrous Alloys
- Hardenability is the capability of an alloy to be hardened by heat treatment
- It is a measure of the depth of hardness that can be obtained by heating and subsequent quenching
- The fluid used for quenching the heated alloy also affects hardenability
Heat Treatment of Non-Ferrous Alloys and Stainless Steel
- Solution treatment: heating the alloy to within the solid-solution phase and then cooling rapidly
- Precipitation hardening:
- Aging: a time and temperature dependent process, also known as age hardening
- Maraging: a precipitation-hardening treatment for a special group of high strength iron-base alloys, derived from martensite age hardening
Annealing
- Annealing is the restoration of a cold-worked or heat-treated metal or alloy to its original properties
- It increases ductility, reduces hardness and strength, or modifies the microstructure
- Annealing also relieves residual stresses in a manufactured part for improved machinability and dimensional stability
The Annealing Process
- Heating the workpiece to a specific range of temperature
- Holding it at that temperature for a period of time
- Cooling it slowly
Classifications of Annealing
- Process annealing: restoring ductility, part or all of which may have been exhausted by work hardening during cold working
- Stress-relief annealing: reducing or eliminating residual stresses
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Description
Understanding the properties of metal alloys, focusing on ferrous alloys and their heat treatments. Learn about self-diffusion and its influencing factors.
