Chapter Q: Q Quintal

Q

Symbol for quantity of electrical charge; (2) symbol for quantity of heat; (3) symbol for quantity of light.

q

Symbol for heat flow rate although the symbol ? is preferred.

QC

Abbreviation for quality control.

quadrant

Quarter of a circle.

quad

A unit of energy equal to 10 ¹⁵ btu.

quadrilateral

Referring to a four-sided figure.

quality control (QC)

The maintenance of a specific level of quality during the manufacturing process, to ensure a consistently good product. Techniques include physical sampling and statistical quality control, the gathering and analyzing of quality data, and action are taken if the quality deviates by a specified amount.

quart

A unit of liquid or dry measure equal to 0.25 gallon (U.S.) = 0.9464 liter liquid; 1.1012 liters dry.

quench

Rapid cooling of metals or alloys by immersion in cold water or oil.

quench annealing

Annealing an austenitic alloy by solution heat treatment.

quench hardening

The process of hardening a ferrous alloy by austenitizing and then cooling rapidly enough so that a substantial amount of the austenite transforms to martensite.

quenching

The operation of rapid cooling hot metal in a suitable medium such as liquids (water, brine, oil), gasses (air), or solids. An essential part of the tempering process, especially for steels and alloys. When the quench time of molten metal is extremely short (less than a second), the final product will have an amorphous or glasslike structure, because crystallization will not occur.

quick-change toolholder

A lathe toolholder made...