Torsional stiffness

The torque required to produce unit angular displacement, either of the whole coupling or of part of the coupling such as the spacer. Note: With some types of couplings, the torsional stiffness may not be constant but may be a function of the magnitude of the torque and, with oscillating torques, also the frequency.

Thermocouple

A device for measuring temperatures, consisting of lengths of two dissimilar metals or alloys that are electrically joined at one end and connected to a voltage-measuring instrument at the other end. When one junction is hotter than the other, a thermal electromotive force is produced that is roughly proportional to the difference in temperature between the hot and cold junctions.

Thermomechanical Working

A general term covering a variety of processes combining controlled thermal and deformation treatments to obtain specific properties. Same as thermal-mechanical treatment.

Time Quenching

A term used to describe a quench in which the cooling rate of the part being quenched must be changed abruptly at some time during the cooling cycle.

Transformation Hardening

Heat treatment comprising austenitization followed by cooling under conditions such that the austenite transforms more or less completely into martensite and possibly into bainite.

Transformation-Induced Plasticity

A phenomenon, occurring chiefly in certain highly alloyed steels that have been heat treated to produce metastable austenite or metastable austenite plus martensite, whereby, on subsequent deformation, part of the austenite undergoes strain-induced transformation to martensite. Steels capable of transforming in this manner, commonly referred to as TRIP steels, are highly plastic after heat treatment, but exhibit a very high rate of strain hardening and thus have high tensile and yield strengths after plastic deformation at temperatures between about 20 and 500 °C (70 and 930 °F). Cooling to -195 °C (-320 °F) may or may not be required to complete the transformation to martensite. Tempering usually is done following transformation.

Thermal Electromotive Force

The electromotive force generated in a circuit containing two dissimilar metals when one junction is at a temperature different from that of the other. See also thermocouple .

Thermal Fatigue

Fracture resulting from the presence of temperature gradients that vary with time in such a manner as to produce cyclic stresses in a structure.

Thermal Shock

The development of a steep temperature gradient and accompanying high stresses within a structure.

Thermal Stresses

Stresses in metal resulting from nonuniform temperature distribution.