In the ERW steel pipe production, electric resistance welding played an important role. Some customer don't know clearly about electric resistance welding, so pipe manufacturer Great Steel Pipe will share types of electric resistance welding for all of you. There are three basic types of electric resistance welding: solid state, fusion, and reflow soldering.
In solid state, also called thermo-compression, there are dissimilar materials with dissimilar grain structure, e.g. molybdenum to tungsten, which are joined using a very short heating time, high weld energy, and high force. There is little melting and minimum grain growth, but it has a definite bond and grain interface. Thus the materials actually are still in the solid state. The bonded materials usually has excellent shear and tensile strength, but peel strength is poor.
In fusion, either similar or dissimilar materials with similar grain structures are heated to the melting point (liquid state) of both. The subsequent cooling and combination of the materials forms a “nugget” alloy of the two materials with larger grain growth. Typically, high weld energies at either short or long weld times, depending on physical characteristics, are used to produce fusion bonds. The bonded materials usually has excellent shear and tensile strength.
In reflow soldering, a resistance heating of a low temperature brazing material is used to join either dissimilar materials or widely varied thick/thin material combinations. The brazing material must “wet” to each part and possess a lower melting point than the two workpieces. The resultant bond has definite interfaces with minimum grain growth. Typically the process requires a longer (2 to 100 ms) heating time at low weld energy. The bonded materials usually has excellent tensile strength, but shear and peel strength is poor.