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Q-BOP
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.

Qualification Trials
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.

Quality
A term used to denote the degree of perfection of the steel sheet. Often, for sheet products, relative quality refers to the degree of perfection of the surface, i.e., the lack of scratches, absence of slivers, etc. Quality can also refer to other attributes such as internal soundness, dimensional control, etc.

Quarter Hard (No. 3 Temper)
(A) In low carbon cold-rolled strip steel, a medium soft temper produced by a limited amount of cold rolling after annealing. (B) In brass mill terminology. Quarter hard is one B and S number hard or 10.95% reduction. (C) In stainless steel terminology tempers are based on minimum tensile, or yield strength. For Chromium-Nickel grades Quarter Hard Temper is 125,000 T. S., 75,000 Y.S. min.

Quench Aging
Aging that occurs after quenching following solution heat treatment.


Quench Hardening
Hardening a ferrous alloy by austenitizing and then cooling rapidly enough so that some or all of the austenite transforms to martensite. The austenitizing temperature for hypoeutectoid steels is usually above Ac3 and for hypereutectoid steels usually between Ac1 and Ac (cm).

Quench Hardening (Steel)
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.

Quenching
In the heat treating of metals, the step of cooling metals rapidly in order to obtain desired properties; most commonly accomplished by immersing the metal in oil or water. In the case of most copper base alloys, quenching has no effect other than to hasten cooling.

 

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