The main reason for hot cracking; They are metallic compounds with low melting temperature, which are formed by elements such as sulfur and phosphorus and have a high tendency to aggregate at the grain boundaries. If these compounds are located in the weld seam or in the region under the influence of heat, they spread towards the grain boundaries and cause cracking when the weld seam cools and tensile stresses occur.

It is recommended that the amount of ferrite in the structure should be at least 4% in order to obtain resistance against the risk of hot cracking. The presence of ferrite is accurately determined by magnetic measuring instruments calibrated in accordance with AWS A.4.2.
The aim is to determine the amount of ferrite (iron) in a non-destructive, precise and accurate manner in production, delivery or in the laboratory according to the magnetic induction method.