Chapter Five Quiz Flashcards
By adding a prescribed amount of copper to an HSLA steel, the following additional benefits can occur?
Atmospheric corrosion resistance is improved.
Fine grain steel versus coarse grain steel heated at a range of 800 to 1000 ᵒC would exhibit which of the following?
Same grain sizes.
Cold forming has certain advantages over other forming methods. Which of the following is an advantage of the cold forming method?
Gives good finish and close dimensional tolerances.
Grain size can influence the properties of steel in significant ways. Which heat treatment is usually selected to improve a steel’s toughness?
Normalizing reduces grain size to increase toughness.
There is a major group of low alloy steels intended for various structural applications and have higher yield strengths than regular carbon steels. What are these steels generally known as?
HSLA. High strength low alloy steels.
What is the makeup of the microstructural component known as pearlite?
Pearlite can be layered structure of cementite and ferrite.
Since BCC iron dissolves very little carbon, most of the carbon in a steel below 723 °C is rejected from the BCC ferrite. The carbon will be present in the form of which of the following?
An iron carbide which is chemically combined and known as cementite.
In basic carbon steels, many microstructures can be formed by the process of heating and cooling as in annealing or welding. Of these microstructures, which would be the hardest?
A fully martensitic structure.
How can the structure of martensite be improved to increase its toughness but maintain the significant strength of the steel?
By tempering the martensite at temperatures where no changes take place in the crystal structure.
There are several types, grades, and quality of steel. How can a “killed” steel be defined?
Killed steel is fully deoxidized normally silicon and aluminum and no gas evolution occurs.
If a steel had been rolled in only one direction, which of the following would be true of that steel’s ductility?
Ductility of the steel is greatest in the rolling direction.
Changing the quantity of what element in steel had greatly reduced the incidence of lamellar tearing in the modern steelmaking era?
Decreasing Sulphur.
When pure iron begins to freeze slowly, it goes through changes in the atomic lattice from a temperature of 1536 ° C down to 0 ° C. What are these changes?
From BCC to FCC and back to BCC.
The basic oxygen furnace makes use of what property to assist in removing impurities from the melt (e.g. phosphorous)?
A refractory lining of basic material.
When quenching a steel from the austenite range, it’s possible to get a microstructure of martensite. What may be the properties of this martensitic structure?
Microstructure leads to high strength but lacks toughness.
When a steel is heated to a temperature to cause the structure to transform to austenite, new grains must grow in a process called recrystallization. If the recrystallization temperature is allowed to rise and maintained for a longer period of time, what is the result?
Grain growth occurs and on cooling, toughness of steel will be reduced.
Which microstructure in the phase diagram of carbon steel would exhibit complete dissolution of carbon?
Pearlite.
Iron can change its crystallographic form as temperature changes. What form does iron take at a temperature of 250 ° C?
BCC ferrite lattice form.
There are several heat treatment approaches to change the properties of a particular steel. One of these is annealing. What advantage can annealing give?
Soften steel and improve machinability.
Which one of the unique crystallographic structures of iron can dissolve a lot of an element critical to the properties of steel?
FCC can dissolve up to 1.7% carbon.
Steel can be strengthened in many ways, but there is only one approach that will increase both strength and toughness. Which of the following methods will achieve this?
Increasing number of grain boundaries by grain refinement.
What kind of carbon content would one expect in a specification that covers chemistries for cold chisels and band saws?
0.5-00.8.
Most metals do not exist in the earth in their elemental form. They are usually combined with other elements in an ore and must be smelted to separate the metal from its ore. What are the most common elements that are combined with metals prior to smelting?
Oxides and sulphides.
When force is applied to a bar, plastic deformation may occur. This phenomenon is called slip, and this is because of dislocation. Dislocation is:
Local distortion that occurs at atomic levels as the atoms try to fit the proper pattern.
