Welder Training & Certification

 

5. METAL { MATALLURGY }

The science and art applied to metals.

Two thirds of all known elements on Earth are metal. Metal is define or described by its (chemical characteristics, physical qualities & mechanical properties.) Metal is usually opaque, dense, solid at room temperature, possesses metallic (peculiar) luster, fusibility, high conductivity for heat and electricity and in electrolysis carries a positive charge.

Metallurgical Processes

1. Mining and extracting metal from its ore or natural form.

2. Refining metal for its intended use.

3. Processing metal into raw stock.

4. Fabricating raw stock into a finnished product.

 Characterisitcs - Qualities - Properties - of Metal:

Mechanical *

The mechanical properties of a metal can be described as those quantifiable properties that enable the metal to resist externally imposed forces / loads without failure "The strength of the metal". An example of mechanical properties: Tensile strength, Ductility, Hardness, Malleability,

Physical

Physical properties are used to identify or describe a metal by other than mechanical properties. These may include: color, density {weight}. conductivity {heat and electricity}. melting temperature, magnetism.

Chemical

Chemical properties determines the way a meta may react when combined with other elements under a variety of environmental and laboratory conditions" The metals reactiveness" {CHART}

A. Alloys: An alloy is an intimate mixture of two or more elements of which at least one is a metal. Alloys are engineered by Metallurgist for specific uses, purposes and applications. Basically an alloy is made up of a base metal / element and added alloy elements, Example; Bronze = copper / Tin, Brass= copper / zinc.

B. Ferrous metal alloys: " Iron or dominated by iron " Example: Iron ore, Pig iron, Wrought iron, Cast Iron, Steel

C. NonFerrous metals alloys: " No Iron or iron of insignificant amounts " Example: Aluminum, Magnesium, Copper, Tin

D. Heat treating:

To change the mechanical, physical and / or chemical characteristics, qualities and properties of a metal by the application of a specific or specified heating procedure. The procedure basicly includes 1. Heating the metal to a specified temperature by a specified means. 2. Holding it (soaking) at that temperature for a specified time. 3. Cooling ( quenching) the metal at a specified rate in a specified medium or atmosphere.

E. Weldable Alloys: Typically ferrous and nonferrous alloys.

F. Refractory Alloys. Reactive Alloys. Exotic Alloys. Metalloids. Composites. Precious Metals.

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TASK LIST I * TASK LIST II * TASK LIST III