Archive for November, 2011

Zinc Alloys

What is Zinc Alloy ?

Zinc Alloys are combinations of zinc with one or more other metals. If  zinc is the primary constituent of the alloy, it is a zinc-base alloy. Zinc also is commonly used in varying degrees as an alloying component with other base metals, such as copper, aluminum, and magnesium. A familiar example of the latter is the association of varying amounts of zinc (up to 45%) with copper to produce brass.

Zinc Alloy Buckle

Zinc, a crystalline metal with moderate strength and ductility, is seldom used alone except as a coating. After iron, aluminium and copper, zinc is usually the fourth-most used metal. There are many wrought alloys with various alloying elements to improve workability and strenght. There are two major Zinc alloy groups for casting. The first is a standard casting alloy that is primarily Zinc in a hypo-eutectic alloy with less than 5% Aluminum. The Second is the newer group of Zinc-Aluminum alloys. These are hyper-eutectic alloys with up to 27% Aluminum. Both groups are primarily used in die casting.

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Corrosion Stainless Steel

How can stainless steel corrode?

All “stainless” steels can corrode under the wrong conditions. Remember that most of the metal is still iron and can corrode or rust depending on how much stress it is exposed to. One of the worst things you can do to stainless steel is expose it to chlorides. The better grades can withstand a lot of abuse, but most grades can eventually fail when exposed to chlorides in bad atmospheres. Some grades of “stainless” steel have very poor resistance to corrosion. They are marginally better than carbon steel, but when correctly hardened and passivated or electropolished can give fairly good performance. The grade of steel must reflect the exposure conditions and performance required.

Corrosion Stainless Steel Pipe

The main reason for the existence of the stainless steels is their resistance to corrosion. Chromium is the main alloying element, and the steel should contain at least 11 %. Chromium is a reactive element, but it and its alloys passivate and exhibit excellent resistance to many environments. Higher Cr contents may be necessary for to improve the corrosion resistance of stainless steels in more aggressive media. Among other alloying elements, Nickel is the most important : it is added to control the alloy microstructure and to improve the corrosion resistance in acidic or caustic media. The addition of other elements such as Molybdenum, Tungsten, Copper, Silicon, Titanium, Niobium, Nitrogen enables a wide range of properties to be obtained.

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Gas Welding - Oxyacetylene Gas Welding

Oxy-fuel welding - a Definition

Gas Welding or Oxy-fuel welding are processes that use fuel gases and oxygen to weld and cut metals, respectively. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903.

Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the workpiece material (e.g. steel) in a room environment.

A common propane/air flame burns at about 3,630 °F (2,000 °C), a propane/oxygen flame burns at about 4,530 °F (2,500 °C), and an acetylene/oxygen flame burns at about 6,330 °F (3,500 °C).

Oxy-fuel is one of the oldest welding processes, though in recent years it has become less popular in industrial applications. However, it is still widely used for welding pipes and tubes, as well as repair work.

It is also frequently well-suited, and favored, for fabricating some types of metal-based artwork. In oxy-fuel welding, a welding torch is used to weld metals.

Welding metal results when two pieces are heated to a temperature that produces a shared pool of molten metal. The molten pool is generally supplied with additional metal called filler. Filler material depends upon the metals to be welded.

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    • Corrosion Stainless Steel November 1, 2011
      All "stainless" steels can corrode under the wrong conditions This is a content summary only. Visit my website for full links, other content, and more! […]
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      Gas Welding or Oxy-fuel welding are processes that use fuel gases and oxygen to weld and cut... This is a content summary only. Visit my website for full links, other content, and more! […]
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