|What is the welding material?|
The joint method that melting by heat or pressure and making each metal i.e. steel unite secondly is called “Welding”. Added metal material when welding is welding material. Welding material and base metal unite and form weld metal when these are melted and solidified.
The weld metal becomes the discontinuity point of the shape and the metal property. Therefore that becomes often the starting point of the destruction phenomenon generating by some kind of power acting. So if the performance of weld metal is bad, the soundness of the structure including this weld metal is inferior with no matter how superior base metal.
You will understand that the welding materials added in order to form weld metal have very important role.
|The action of welding materials|
The welding material have two kinds. One is the melting electrode type which is generating the arc by oneself as heat source. Other one is the un-melting electrode type which is added as the filler in arc or laser beam i.e. heat source generated by the other method. Generally, welding materials have the following roles.
|1) Making the arc generation easy and stable. (in the case of the melting electrode type)|
|2) Refining harmful oxygen by the reduction reaction with additional some elements in molten pool, then forming the soundness weld metal.|
|3) Supplying the necessary elements amount to get the enough some characteristics such as tensile strength, impact toughness, hardness, and corrosion toughness required against weld metal.|
|4) Getting the good bead shape and appearance by control viscosity and surface tension of the molten pool.|
|5) Filling the gap between joined materials.|
Due to the above, various kinds of elements are added in welding materials depending on a purpose.
For example, silicon(Si) and manganese(Mn) are added to refine oxygen, molybdenum(Mo), chrome(Cr) and nickel(Ni) are added to improve strength, impact toughness, and corrosion toughness, and titanium(Ti) is added to improve the arc stability in welding material for steel.
It is necessary for appropriate welding materials to choose by kind of base metal, welding method, welding condition, required characteristics, and cost etc.
Fig.1 Diagram of Shielded Metal Arc Welding method (SMAW) and Gas Metal Arc Welding method (GMAW)
Fig.2 Reduction reaction in the molten pool at the GMAW method and role of welding materials
|Relationship of welding materials and social|
Welding materials are the indispensable for the production of the steel structure. The member companies of JWMA contribute to the society by the supply of good welding materials.