| Continuously cast ductile iron bar stock is produced in a wide variety of sizes and shapes, including rounds, rectangles and special shape cross sections. It often is used as an alternative to gray iron castings. The continuous casting process eliminates typical foundry defects, such as gas holes, hard spots, slag inclusions and inconsistent properties, that result from different molding methods. Bars are cast through a water-cooled graphite die mounted on the bottom of a large bar machine crucible. The ferrostatic head pressure created by the molten metal in the bar machine crucible forces iron into the die, producing a very fine-grained microstructure. The outer “rim” is the only part of the bar that is solid when it exits the die. The core is molten iron. Heat from the molten iron core reheats the rapidly chilled outer skin, producing a homogenized microstructure that is cooled to room temperature in still air. Gray iron bar stock’s microstructure consists of graphite flakes in a solid metal matrix. The solid metal matrix, in the class 40 grades (Dura-Bar grade G2), is pearlite. The flake graphite provides excellent vibration damping for gears and machine tool components. Textile plant machinery utilize a lot of gray cast iron, because the damping coefficient reduces the factory noise The same holds true for machine tool components and automotive gears. Compared to ductile iron, which has strengths closer to carbon steel, gray iron is the weaker, more brittle member of the cast iron family. Dura-Bar G2 is still considered an engineered material, having properties that are more than suitable for a wide variety of applications. Composition: Typical chemical composition and ranges, actual values depend on cross section size. Information provided by Dura-Bar. |
