|
|
 Iron Castings
Ductile Iron Castings: Since ductile iron was developed in the
1940s, this remarkable metal has proved its value in tens of thousands
of engineering and casting applications. Ductile iron is created by an
alloying process, which converts the crack-promoting graphite flakes of
gray iron into nodules. With this micro-structural transformation, the
metal acquires superior ductility, elongation characteristics and
machinability. The ductile iron family offers the design engineer a
unique combination of strength, wear and fatigue resistance and
toughness as well as excellent ductility characteristics. In all its
grades, ductile iron exhibits mechanical properties that make it an
ideal alloy for investment casting. Tiny amounts of magnesium or cerium
are added to these alloys to slow down the growth of graphite
precipitates by bonding them to the edges of the graphite planes. Along
with careful control of other elements and timings, the carbon
separates into spheroidal particles as the material solidifies. Its
properties are similar to malleable iron but parts of it can be cast
with larger sections.
Iron Castings: Essentially an alloy of iron, carbon (2-4%) and
silicon in which the carbon is present in excess of the amount which
can be retained in solid solution in austenite at the eutectic
temperature. When cast iron contains a specially added element or
elements in amounts sufficient to produce a measurable modification of
the physical properties of the section under consideration, it is
called alloy cast iron. Silicon, manganese, sulfur and phosphorus, as
normally obtained from raw materials, are not considered alloy
addition. It has a typically lower cost than competing materials and a
relatively low cost per unit of strength than other materials. With its
wide range of mechanical properties, Iron Casting is suitable for many
engineering applications, especially where intricacy of design is
required. Iron Casting is commonly used when ductility is not a factor.
It is well suited for General Machinery, Stock Fittings, Automotive
Parts, Valve Bodies and Railroad Accessories. Iron Casting provides
advantages in the areas of Cost, Excellent Machining, Dampening
Capacity (ability to absorb vibrations), Good Wear Characteristics
(self lubricating) and Compressive Strength.
|
