Calcium inclusion spheroidization
Calcium reacts with sulfide and oxide inclusions in the weld, forms spheroids, and prevents porosity.
Physicochemical mechanism of action
Calcium chemically reacts with the brittle sulfide and oxide stringer inclusions in the molten pool. This reaction forms globular, harmless spheroids of calcium sulfides or calcium oxides.
Metallurgical relevance & risks in welding
Calcium inclusion spheroidization prevents porosity and improves weld strength. However, too low a calcium content can result in incomplete reaction of inclusions, leaving them brittle, which leads to hot cracking and fracture points.
Workshop practice & instructions
Ensure the calcium content in the weld is precisely controlled. A typical content is 0.1–0.2% for plain carbon steels and higher for austenitic steels. Monitor the temperature in the weld pool and ensure homogeneous distribution of calcium.