Industries that use gray iron castings include: agriculture, construction, automotive, construction, electronics, irrigation, machine building, transportation and ventilation.
Gray iron castings provide durability, hardness and strength to any operation in which they are used. There are many applications for gray iron castings. As non-combustible building elements, they provide excellent fire protection for wooden support structures. Additionally, their graphite/graphite flake content can be used for energy dissipation in components such as engine blocks and crankshafts, which depend on the damping of mechanical vibrations.
Products produced
Gray iron castings are frequently used in the manufacture of: valves, housings, engine blocks, molds, pump casings, pipes, brake drums, trim and gray iron cookware.
history
The first iron to be cast was gray iron, which has a long and illustrious history in our world. The earliest cast iron products were made in China, around the 5th century BC. At that time, iron was cast into weapons, simple pots, plowshares and guns. Also, between the 9th and 4th centuries BC, malleable cast iron was developed. Malleable cast iron is easier to work with. The Chinese likely shared their craft of iron casting along the Silk Roads. Still, Western Europeans did not begin casting iron until the 15th century AD. Following Henry VIII's instructions, artisans used the foundry process to create heavy cannon for the Royal Navy.
Gray Iron Castings
Gray Iron Castings – OSCO Industries, Inc.
Centuries later, in 1707, an Englishman named Abraham Darby discovered a way to cast iron pots with thin walls. He uses it to make cast iron cookware. Using the same method, other manufacturers made cast iron shields and some body armor parts. In the mid-1700s, this type of iron casting was popular for use in armor.
In the 1770s, James Watt developed an atmospheric steam engine, an updated version of Thomas Newcomen's earlier steam engine, which made it easier to cast gray iron, and Parts are also more precise and stronger.
Before the advent of steel, gray iron castings were used for structural components of bridges. They switched to steel in the early 1800's because of its higher tensile strength and hardness. Gray cast iron proved to be more successful in the construction of buildings such as textile mills. Iron construction helps prevent fires. Textile mills especially benefit from this as they are full of combustible fibers and combustible dust. Iron was so useful that eventually manufacturers started building their equipment from cast iron as well.
Gray iron castings continued to be popular throughout the last century. For example, in 1967 gray cast iron was minted approximately two and a half times as much as other cast metals. That year, manufacturers cast more than 14 million tonnes of gray iron products.
Today, although gray cast iron is one of the oldest types of cast iron, it is still routinely cast. This is a testament to its usefulness. Over the past decade, manufacturers have greatly improved the dimensional control with which they can cast gray iron. They were also able to improve the quality of thin sections. Dimensional control and product quality will only improve in the coming years as manufacturers continue to refine these practices. To make better parts, manufacturers are also working on mold surface treatments that allow them to skip post-casting mold blasting. Skipping this step means casting is faster and less expensive. As always, they are also investigating ways to strengthen gray cast iron.
Material Technology
The generally accepted composition of gray cast iron is 95% iron by weight, plus 1% to 3% silicon and 2.1% to 4% carbon.
The large amount of silicone in gray iron produces graphite when heated. Graphite is the element that causes the coloring of gray cast iron. Gray graphite can be seen when gray cast iron breaks. When it ruptures, graphite flakes are produced, evidence of its graphite microstructure. In its natural form, graphite flakes look like true flakes. On a polished surface, cast iron graphite flakes appear as thin lines. Graphite flakes crack easily, a property that actually makes gray iron more castable. All in all, gray iron has a graphite content between 6% and 10% by volume.
The presence of carbon changes the tensile strength and hardness. The higher the carbon content, the higher the tensile strength and hardness.
The exact appearance of individual gray irons depends on temperature and time. In addition to appearance, variable properties of castings include: thermal conductivity, tensile strength, hardness, energy dissipation, wear resistance and deformation, and melting point.
Other elements may be present in gray iron castings. Some may have been intentionally placed there by the manufacturer to alter specific properties. Others, like graphite, may appear by chance. The most prominent of these are manganese, carbon and sulfur. When added to molten gray cast iron, manganese promotes the formation of pearlite during the cooling phase, while sulfur increases hardness. Other elements may be present, but to a lesser extent.