| Blind Bole | (english) A hole made in a workpiece that does not pass through it. |
| 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 Off | (english) 1) Wooden separators which are used at both the bottom of a lift and between IPM's (bundles) of a lift. 2) The act of placing 4x4s between the lifts in the piler's box. |
| Block, Jo | (english) Shop name for a Johnnson gage block, a very accurate measuring device. |
| Blocker | (english) Preform die or impression, used when part cannot be made in a single operation. |
| 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. |
| Blooming-Mill | (english) A mill used to reduce ingots to blooms, billets slabs, sheet-bar etc., |