Glossary Terms

SHIM. A thin piece of material placed between two surfaces to obtain a proper fit, adjustment, or alignment. The piece can also be analyzed to measure furnace carbon potential (that is, because while in the furnace it will quickly carburize to a level equal to the furnace carbon potential).

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.

SLOT FURNACE. A common batch furnace where stock is charged and removed through a slot or opening.

SNAP TEMPER. A precautionary interim stress-relieving treatment applied to high-hardenability steels immediately after quenching to prevent cracking because of delay in tempering them at the prescribed higher temperature.

SOAKING. Prolonged holding at a selected temperature to effect homogenization of structure or composition.

SOLID SOLUTION. A single, solid, homogenous crystalline phase containing two or more chemical species.

SOLUTION HEAT TREATMENT. Heating an alloy to a suitable temperature, holding at that temperature long enough to cause one or more constituents to enter into a solid solution, and then cooling rapidly enough to hold these constituents in solution.