| BLEED-OFF | (english) To divert a specific, controllable portion of pump delivery directly to reservoir. |
| Bleeder | (english) A defect wherein a casting lacks completeness due to moltn metal draining or leaking out of some part of the mold cavity after pouraing has stopped. |
| 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. |
| Blister Steel | (english) High-carbon steel produced by carburizing wrought iron. The bar, originally smooth, is covered with small blisters when removed from the cementation (carburizing) furnace. |
| Block, Jo | (english) Shop name for a Johnnson gage block, a very accurate measuring device. |
| Bloom 2 | (english) A semi-finished hot rolled product, rectangular in cross section, produced on a blooming mill. For iron and steel, the width is not more than twice the thickness, and the cross-sectional area is usually not less than 36 sq. in. Iron and steel blooms are sometimes made by forging. |
| Bloomery | (english) A primitive furnace used for direct reduction of ore to iron. |
| Blow | (english) The impact or force delivered by one workstroke of the forging equipment. |
| Blow Back | (english) A coating defect consisting of a lower coating film weight on the bottom of the coated sheet caused by high velocity air in the oven. Blow back usually occurs with high solids coatings which have little solvent to evaporate and "set" the film. |