14 Questions
What is the minimum chromium composition required in stainless steels?
11%
What is the primary form of carbon in gray cast iron?
Graphite flakes
What is the result of adding magnesium to gray cast iron?
Improved ductility
What is the characteristic of white cast iron?
High hardness
What is coke formed by heating?
Coal
What is the purpose of limestone in the production of coke?
To remove impurities
What is the primary goal of alloying metals?
To improve the properties of the base material
What is the main characteristic of ferrous metals?
They have iron as their main constituent
What is the primary alloying ingredient in carbon steels?
Carbon
What is the characteristic of low-carbon steel?
Low strength and high ductility
What is the typical use of tool steels?
Manufacturing tooling, such as cutting tools and drill bits
What is the carbon content range of high-carbon steel?
Between 0.70% to 1.40%
What is the characteristic of medium-carbon steel?
It can be heat treated to increase strength
What is the characteristic of low-alloy steels?
They have less than 8% total alloying ingredients
Study Notes
Classification of Materials
- Materials selection process is influenced by factors that affect both material and process.
Metals
- Metals are the most commonly used class of engineering materials.
- Metal alloys are formed by combining a metal with one or more other metallic and/or non-metallic materials.
- The goal of alloying is to improve the properties of the base material in some desirable way.
Ferrous and Non-ferrous Metals
- Ferrous metals have iron as their main constituent, such as cast iron, wrought iron, and steel.
- Non-ferrous metals have a metal other than iron as their main constituent, such as copper, aluminum, brass, tin, and zinc.
Ferrous Metals and Alloys
- Ferrous alloys have iron as the base element, including steels and cast irons.
- Carbon steels are basically just mixtures of iron and carbon.
- Low-carbon steel has less than about 0.30% carbon, characterized by low strength but high ductility.
- Medium-carbon steel contains between about 0.30% to 0.70% carbon, can be heat treated to increase strength.
- High-carbon steel contains between about 0.70% to 1.40% carbon, has high strength but low ductility.
- Low-alloy steels, also called alloy steels, contain less than about 8% total alloying ingredients.
- Tool steels are primarily used to make tooling for use in manufacturing.
- Stainless steels have good corrosion resistance, mostly due to the addition of chromium as an alloying ingredient.
- Stainless steels have a chromium composition of at least 11%.
Cast Iron
- Cast iron is a ferrous alloy containing high levels of carbon, generally greater than 2%.
- Gray cast iron is the most common type, with carbon in the form of graphite flakes.
- The addition of magnesium to gray cast iron improves the ductility of the material, resulting in nodular cast iron.
- White cast iron has carbon in the form of carbide, making the material hard, brittle, and difficult to machine.
- Malleable cast iron is produced by heat treating white cast iron.
Coke and Iron Making
- Coke is formed by heating coal to 2100°F (1150°C), then cooling it in quenching towers.
- Limestone (calcium carbonate) is used to remove impurities.
- Cupola or Cupola Furnace is a melting device used in foundries that can be used to melt cast iron.
This quiz covers the materials selection process and the properties of metals, including metal alloys and their formation. Learn about the factors that influence material and process selection in engineering.
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