Slack Quenching

The incomplete hardening of steel due to quenching from the austenitizing temperature at a rate slower than the critical cooling rate for the particular steel, resulting in the formation of one or more transformation products in addition to martensite.

Salt Bath Heat Treatment

Heat treatment carried out in a bath of molten salt.

Saponification Number

A number given to quenching oils that reflects the oils amount of compounding with fatty materials, which thereby helps evaluate the condition of these oils in service. See neutralization number .

Severity of Quench

Ability of quenching medium to extract heat from a hot steel workpiece; expressed in terms of the H value.

Shaker-Hearth Furnace

A continuous type furnace that uses a reciprocating shaker motion to move the parts along the hearth.

Shell Hardening

A surface-hardening process in which a suitable steel workpiece, when heated through and quench hardened, develops a martensitic layer or shell that closely follows the contour of the piece and surrounds a core of essentially pearlitic transformation product. This result is accomplished by a proper balance among section size, steel hardenability, and severity of quench.

Safety Ground

A connection made between equipment (usually the metal chassis, panel, case, or B-minus circuit) and the earth as a protective measure against fire and electric shock.

Saturated Operation

1. The operation of a magnetic core at or beyond its saturation point (i.e., in the region where an increase in coil current produces no change in core magnetization). 2. The operation of a transistor or vacuum tube beyond its saturation point (i.e., in the region where an increase in voltage produces no change in current, or vice versa). Compare UNSATURATED OPERATION.

Scanning Frequency

The number of scans per unit time, usually expressed in lines, sweeps, or channels per second or per minute. Also called SCANNING RATE.

Schering Bridge

A four-arm capacitance bridge in which the unknown capacitance is compared with a standard capacitance. This bridge is frequently used in testing electrolytic capacitors, to which a direct-current polarizing voltage is applied during the measurement.