Zinc Alloy: Ingot and Sheet
All Zinc Products
Zinc, its alloys and its chemical compounds represent the fourth most industrially utilized metal (behind iron, aluminum and copper). Zinc is used in five principal areas of application: In coatings and anodes for corrosion protection of irons and steels; in zinc casting alloys; as an alloying element in copper, aluminum magnesium and other alloys; in wrought zinc alloys; and in zinc chemicals. In the corrosion-protection category, hot dip or continuous galvanizing accounts for the majority of zinc consumption. Almost all of the zinc is used in zinc casting alloys is employed in die casting compositions.
The major product forms of zinc-coated materials include hot dip postfabrication products, sheet, strip, wire and tube. Galvanized sheet is used mainly for building and construction, automotive underbody panels and domestic and household appliances. Electroplating, mechanical plating and sherardizing are normally employed on fasteners and other relatively small objects for which thin, uniform coatings are required.
Zinc-base casting alloys fall into three categories: die casting alloys; foundry alloys; and other casting alloys. Of these three categories, die casting alloys are by far the most important, accounting for more than 25% of all zinc consumption in recent years.
The major use of zinc as a structural material is in alloys for pressure die casting. These alloys are commonly known as #2, #3, and #5 zinc alloys. Zinc die castings have been in use for more than 50 years and are highly castable, easily finished, economical materials with good mechanical properties. They are used for a wide range of decorative and light structural parts and lend themselves readily to rapid mass-production techniques such as those required in the automotive industry.
#3 is characterized by good impact strength and long-term dimensional stability. #5 exhibits somewhat higher tensile strength and creep resistance than #3 but has lower impact strength at elevated temperatures. #7 is a high-purity version of alloy #3 and thus has similar mechanical properties but exhibits superior casting and finishing characteristics.
Zinc foundry alloys, commonly referred to as the “ZA” alloys, have been developed during the past 20 years and are now increasing in commercial usage. The ZA alloys are suitable for casting by sand, permanent mold, graphite permanent mold, shell mold and high-pressure die casting methods. The graphite permanent mold process was specially developed on the basis of the good castability and low casting temperature of the ZA alloys.