Intermetallic phase formation
Intermetallic phase formation is the occurrence of compounds from different metals with fixed compositions and brittle properties. These phases can impair mechanical properties.
Physical-Chemical Mechanism of Action
Intermetallic phases form by direct bonding of atoms of different metals in a fixed stoichiometric ratio. These compounds often have a brittle crystal structure and are mechanically softer than the base metals involved.
Metallurgical Relevance & Welding Risks
Intermetallic phases can occur in the weld, especially at high temperatures and long heat times. They lead to a loss of toughness and increase susceptibility to cracks and wear. These phases are particularly dangerous in stiff steels like martensite or ferrite.
Workshop Practice & Action Instructions
To avoid intermetallic phase formation, weld times should be minimized and heat zones controlled. At high stress limits, it is especially important that the material is cooled quickly (t8/5 < 10 s). For such steels, use special welding processes like gas welding or plasma welding that allow rapid cooling.