| Activation | (english) The changing of the passive surface of a metal to a chemically active state. Contrast with passivation. |
| Back Rake | (english) The angular surface ground back from the cutting edge of cutting tools. On lathe cutting tools. The rake is positive if the face slopws down from the cutting edge toward the shank, and negative if the face sloopes upward toward the shank. |
| Backer (back-up plate) | (english) A “tool” or reinforcing part, which presses against the outer surface of an extrusion die, supporting it against the pressure of the extruding metal. The backer has an opening larger than the die aperture, allowing the extruded product to emerge without marring its soft surface. |
| Basic Oxygen Process 2 | (english) A steel making process wherein oxygen of the highest purity is blown onto the surface of a bath of molten iron contained in a basic lined and ladle shaped vessel. The melting cycle duration is extremely short with quality comparable to Open Hearth Steel. |
| Bevel | (english) Angle formed between the prepared edge of the end of tube and a plane perpendicular to the surface. Standard pipe bevel is 30 degrees. |
| Blacking Hole | (english) Irregular-shaped surface cavities in a casting containing carbonaceous matter. Caused by spilling off of the blacking from the mold surface. |
| Blast Cleaning (blasting) | (english) A process for cleaning or finishing metal objects by use of an air jet or centrifugal wheel that propels abrasive particles (grit, sand, or shot) against the surfaces of the workpiece at high velocity. |
| Blasting (Blast Cleaning) | (english) A process for cleaning or finishing metal objects by use of an air blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Small, irregular particles of steel or iron are used as the abrasive in grit blasting, and steel or iron balls in shot blasting. |
| Blister | (english) 1) Coating defect consisting of the formation of bubbles in a coating, which appear as hemispherical elevations. The blisters are hollow, and are usually caused by entrapped air or solvent. 2) A raised spot on the surface on the surface of metal due to expansion of gas which causes a subsurface metal separation such as inclusions and small laminations. |
| Blister 2 | (english) A defect in metal, on or near the surface, resulting from the expansion of gas in a subsurface zone. Very small blisters are called pinheads or pepper blisters. |