|The testing required for a new process adopted to make certain grades of |
steel with exacting end uses. In order for the process to become qualified,
the steel made by the process must be tested.
|Quarter Hard Temper|
|Cold Rolled steel produced to a Rockwell hardness range of 60 to 75 on the |
B scale. Product of this temper is intended for limited bending and cold
forming and can be bent 90 degrees in the rolling direction and 180 degrees
across the rolling direction over its own thickness.
|Quench aging is a type of artificial or accelerated aging which causes a |
change in the properties of steel that occurs gradually with time at
moderately elevated temperatures after a hot working heat treatment. It is
a consequence of the precipitation of carbon, nitrogen or both, from
supersaturated solid solution in ferrite. The consequences of quench aging
are increased hardness, increased yield and tensile strength, decreased
elongation and reduction of area in tension test, increased temperature of
transition from ductile to brittle fracture in a notch-impact test, an
increase in coercive force and a decrease in magnetic permeability.
|Annealing an austenitic ferrous alloy by solution heat treatment followed |
by rapid quenching.
|A process of hardening a ferrous alloy of suitable composition by heating |
within or above the transformation range and cooling at a rate sufficient
to increase the hardness substantially. The process usually involves the
formation of martensite.
|Cooling very rapidly from a high temperature by immersing in water or some |
|Quenching and Tempering|
|This treatment is given in addition to annealing in order to develop the |
optimum mechanical properties and in place of annealing when the amount of
machining or cutting to be done is not great. It consists of first heating
the steel above the critical range, and then cooling it rapidly by
immersing it in a liquid cooling medium such as oil or water. This is
followed by heating the steel to an intermediate temperature, very seldom
higher than 650oC and usually somewhat lower.
|Cracks formed as a result of thermal stresses produced by rapid cooling |
from a high temperature.
|Tank of water used to quickly cool the strip before it reaches the delivery |
end of the line.
|Water that keeps boiler duct work cool.|
|Modified Basic Oxygen Furnace in which the oxygen and other gases are blown |
in from the bottom, rather than from the top. While the Q-BOP stirs the
metal bath more vigorously, allowing for faster processing, the design
produces essentially the same steel grades as the top-blowing basic oxygen
furnace. Today's state-of-the-art furnace design combines the previous
technologies: 60% of the oxygen is blown from above, with the rest blown
through the bottom of the vessel.