Line H Exam: Metallurgy Flashcards
What is elongation?
Elongation is the measuring of ductility in relation to the measurement of tensile strength.
If the material is ductile, it can stretch a lot without breaking. This ability to stretch a lot is what we call elongation.
What symbol is used to signify elongation?
“e”.
What begins to form during elongation. Describe it.
During elongation, a neck begins to form creating an almost hourglass figure, and then the the specimen will break along its neck. This process is how elongation is tested,
Define the difference between elastic and plastic deformation.
Elastic deformation is where the material returns to its original shape once the stress is removed.
Plastic deformation is irreversible.
What is the difference between testing for elongation and testing for tensile strength?
Elongation testing is to measure how much the material can stretch or lengthen before it breaks.
Tensile strength testing is to determine the maximum force that a material can withstand while being stretched before it breaks.
Elongation is for stretching, tensile is for strength.
What is the requirement for strength testing?
The strength of metal is its ability to resist changing its shape or size under the effect of external load.
What is Tensile Strength?
Tensile strength is the ability of a piece of metal to resist a load that tends to pull apart.
What is Yield Point?
The yield point in tensile strength testing is the moment when a material starts to deform permanently. Up to this point, if you stop pulling on the material, it will return to its original shape. **Beyond the yield point, the material won’t go back to its original shape and will be permanently stretched. The yield point marks that critical stretch where it starts to stay deformed. **
(pulling on a piece of elastic; it snaps back until stretched too far, then it stays stretched.)
Define yield point and yield strength.
Yield Point is the specific point where a material starts to deform permanently when stressed. The exact moment the material will not return to how it was on its own.
Yield Strength is the amount of stress needed to reach the yield point. **It’s a measure of how much force it takes to make the material start deforming permanently. **
What is UTS?
UTS stands for Ultimate Tensile Strength.
UTS is the maximum stress (due to tensile loading) a material can manage without fracture. After this point, no matter how little, any additional load will cause fracture.
How do you calculate UTS (ultimate tensile strength)?
** UTS = F/A **
** F is the maximum force (or load) applied to the material during the tensile test.**
** A is the original cross-sectional area of the material.**
What is the CVN test?
The Charpy V-notch test (CVN) is a way to measure the impact strength and toughness of a material, which tells us how well it can absorb energy and resist breaking when hit by a sudden force.
Impact Strength: Focuses on resistance to a sudden impact.
Toughness: Shows overall energy absorption and plastic deformation ability, telling how much total energy the material can take before fracturing.
What is the melting point of steel?
** 1535 °C (2800 °F).**
How is pure iron made?
Pure iron is made by reducing the ore and removing impurities in a blast furnace.
What is pig iron?
Pig iron is produced in the first step of steel production. Pig iron is the product of smelting iron ore with a high-carbon fuel and reductant such as coke.
This iron is too brittle to be useful due to the amount of impurities, so it is transferred to a specific furnace for its production, such as cast iron or steel.
How is cast iron made?
Cast iron is made by remelting pig iron in a cupola furnace alongside scrap steel and other elements. The melted iron modified to composition specifications (added material) and then cast (hence the name) into shapes for later usage.
What is white cast iron?
White cast iron is made by cooling cast iron more quickly than grey cast iron.
Because of the production of cementite, white cast iron is extremely brittle and hard. The resulting material has a white or silvery appearance and cannot be machined or welded.
Describe Cementite (Fe3C)
Cementite (found in white cast iron) is a form of carbon after rapid cooling with no graphite present. Cementite is very hard and brittle and extremely resistant to wear.
Describe white cast irons relation to hardfacing.
White cast irons are sometimes used for hardfacing applications to improve the wear resistance of the softer surfaces of more ductile irons.
What are the three classes of steel (based on their level of deoxidation).
Rimmed
Semi-Killed
Killed
What level of deoxidation is killed steel?
Killed steels are fully deoxidized during the refining process (normally with silicon and aluminum). There is no gas formation to compensate for shrinkage. The ingot is uniform in composition without the partial separation of alloy parts (segregation) that occurs in rimmed steels.
What are the characteristics of Killed Steel?
Killed steel has a consistent make up throughout the entire piece. There are no huge variations in the distribution of elements within the steel, ensuring its make up is even and predictable (unlike rimmed steel which is the opposite of such)
A cavity or pipe will form at the top of an ingot, which must be removed prior to rolling. This is referred to as cropping.
Describe Semi-finished steel.
Semi-finished steel refers to steel products that have been partially processed but are not yet in their final shape or form. Such as a slab that will become a grooved round bar.
How is semi-finished steel formed?
Semi-finished steel is put into a forming process commonly classified into hot and cold working.
Define the difference between hot and cold worked steel.
Hot worked steel products have slightly rounded edges.
Cold worked steel is squared. It has a smoother, shinier surface and more precise dimensions.
