| Q-factor |
(quality factor, sharpness of resonance) A non-dimensional parameter that describes, for a given resonant mode, the sharpness of the peak in the frequency response of a lightly-damped linear oscillator: Q = ωRES/Δω where ωRES is the resonance frequency and Δω is the half-power bandwidth of the resonance. It is inversely related to the damping such that a broad peak corresponds to high damping and a narrow peak to low damping. |
| Quarter hard |
A temper of nonferrous alloys and some ferrous alloys characterized by tensile strength aboutmidway between that of dead soft and half hard tempers. |
| Quench (quenching) |
1. The process of rapid-cooling by plunging an object into a bath of water, oil, salt, molten metal, or other media. It is a method of heat treatment used particularly to form martensite preparatory to tempering steels. The bath temperature is the quench temperature. 2. The suppression of combustion. 3. In a piston engine, the cooling of a fraction of the gases during combustion, typically by reducing the clearance between the piston crown and the cylinder head. |
| Quench aging |
Aging induced by rapid cooling after solution heat treatment. |
| Quench annealing |
Annealing an austenitic ferrous alloy by solution heat treatment followed by rapid quenching. |
| Quench cracking |
Fracture of a metal during quenching from elevated temperature. Most frequently observed in hardened carbon steel, alloy steel, or tool steel parts of high hardness and low toughness. Cracks often emanate from fillets, holes, corners, or other stress raisers and result from high stresses due to the volume changes accompanying transformation to martensite. |
| Quench hardening |
(1) Hardening suitable alpha-beta alloys (most often certain copper to titanium alloys) by solution treating and quenching to develop a martensitic-like structure. (2) In ferrous alloys, hardening by austenitizing and then cooling at a rate such that a substantial amount of austenite transforms to martensite. |
| Quench-age embrittlement |
Embrittlement of low-carbon steels resulting from precipitation of solute carbon at existing dislocations and from precipitation hardening of the steel caused by differences in ferrite at different temperatures. Quenchage embrittlement usually is caused by rapid cooling of the steel from temperatures slightly below Ac1 (the temperature at which austenite begins to form), and can be minimized by quenching from lower temperatures. |
| Quenching |
Rapid cooling. When applicable, the following more specific terms should be used: brine quenching, caustic quenching, cold die quenching, forced-air quenching, intense quenching, oil quenching, press quenching, spray quenching, direct quenching, fog quenching, hot quenching, interrupted quenching, selective quenching, time quenching, and water quenching. |
| Quick coupling |
(quick disconnect, fast coupling) A hose connection allowing rapid assembly or disassembly and comprising a socket and a plug incorporating a springloaded locking mechanism. |
| Quimby screw pump |
A screw pump with two meshing screws, each having a righthand and a left-hand screw. Liquid enters at either end and is discharged from the middle. |
