Welding Slag

Welding flux is used to protect the weld area from contamination.  The flux forms a protective layer over the surface.  In certain cases, it is left as a residue over the weld area.  This is called welding slag. Welding Slag has to be removed in order to be able to view the welded area for …

Shielded metal arc welding

Shielded metal arc welding is one of most popular methods of welding.  Shielded metal arc is simpler than other forms of welding.  It requires an welding transformer kit and an electrode.  Shielded metal arc welding works by creating an electric arc between the work piece and the electrode. The welding transformer can produce high currents.  …

Welding Flux

Welding flux is a substance used during the welding process to shield the weld area from atmospheric contamination.  In metal arc welding, the flux is part of the welding rods.  When the arc is initiated, the high temperature melts the work piece and the welding rod.  The flux coating on the rod also melts and …

Porosity in Welding

Porosity in welding is the formation of air pockets or bubbles in the weld area.  Porosity makes the weld weak and can cause failure of the weld area.  Some of the causes of porosity are Improper shielding Presence of water or moisture on the weld surface Presence of paint, which can get vaporised during the …

Shielding Gas

Shielding gases are gases used in gas arc welding.  Shielding gases serve to insulate the weld are from gases such as oxygen and water vapour.  This is necessary to prevent oxidation at the weld area at high area and porosity(formation of bubbles in the weld).  Inert and semi-inert gases are used for shielding.  Examples are …

Rockwell Scale

The Rockwell scale is a scale to measure hardness.  The scale is based on the depth of the indentation produced on a material.  The test works by using an indentor to makes an indentation. The Rockwell test is a non-destructive testing.  Its setup is easy to install. The indentation hardness is linearly related to tensile …

High speed steels

Hi Speed steels are steels which have high hardness even at high temperatures.  They also have good wear resistance. These steels have molybdenum, vanadium, chromium and tunsten as their constituents.  These elements generally constitute about 7% of the material.  These elements form carbides. The name High Speed Steels was used as they cut faster than …

Quenching

Quenching is process of strengthening and hardening steels and alloys.  Quenching is the quick cooling of a hot metal, such that the phase transformation do not occur. The hardness is increased as the crystal grain size is increased.  Quenching is done in oil or in water.  The medium is chosen depending on the level of …

Tempering

Tempering is a heat treatment used to reduce the hardness of a metal and to increase its toughness and ductility. The internal stresses in the material are relieved during the process.  It is used particularly in iron alloys, such as steel.  It is generally used after quenching.  Quenching causes the material to become hard and …

Galvanizing

Galvanizing is the process of applying a coat of zinc on to a steel surface.  Galvanizing protects the steel from corrosion.  Galvanizing is a very popular method of protection.  The layer of zinc protects the steel from the environment.  In addition, galvanizing also provides galvanic protection.  Galvanic CorrosionGalvanic corrosion when two different metals are joined …