Box Annealing

Annealing a metal or alloy in a sealed container under conditions that minimize oxidation. In box annealing a ferrous alloy, the charge is usually heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly; this process is also called close annealing or pot annealing. See black annealing .

Bainite

A metastable aggregate consisting of dispersed carbide in ferrite resulting from the transformation of austenite at temperatures below the pearlite range but above Ms. Its appearance is in the form of relatively coarse ferrite laths between which carbides are precipitated as platelets if formed in the upper part of the bainite transformation range; acicular, resembling tempered martensite, if formed in the lower part.

Batch Furnace

A furnace used to heat treat a single load at a time. Batch-type furnaces are necessary for large parts such as heavy forgings and are preferred for complex alloy grades requiring long cycles. See car furnace , horizontal batch furnace .

Black Annealing

Box annealing or pot annealing ferrous alloy sheet, strip, wire to impart a black color to the oxidized surface.

Black Oxide

A black finish on a metal produced by immersing it in hot oxidizing salts or salt solutions.

Blank Carburizing

Simulating the carburizing operation without introducing carbon. This is usually accomplished by using an inert material in place of the carburizing agent, or by applying a suitable protective coating to the ferrous alloy.

Back Gouging

The removal of weld metal and base metal from the other side (root side) of a weld joint. When this gouged area is welded, complete penetration of the weld joint is assured.

Butt Joint

A weldment where the material surfaces and joining edges are in or near the same plane.

Balanced Electronic Voltmeter

An electronic voltmeter circuit in which two matched transistors are connected in a four-arm bridge arrangement. The drift in one half of the circuit opposes that in the other half; the resulting drift of the zero point is virtually eliminated.

Backward Diode

A semiconductor diode manufactured in such a way that its high-current flow occurs when the junction is reverse biased. Such a diode is also a negative-resistance device.