To investigate the formation of intermetallic compounds at the laser welded joint of 22MnB5 steel sheet with Al-Si coating

a combination of experimental and theoretical methods was employed. The study focused on the binary and ternary intermetallic compounds formed by the flow of Al into the molten pool and its interaction with Fe and Mn from the base metal in welding. According to the distribution of elements at the interface and the mechanical properties

the types and growth sequence of Al/Fe/Mn intermetallic compounds from the perspective of the maximum nucleation driving force were analyzed in terms of the change in Gibbs free energy of the intermetallic compounds. The results showed that the formation of brittle intermetallic compounds enhances the microhardness in the welded zone. The formation sequence of Al-Fe binary intermetallic compounds occurred firstly

followed by Al-Mn binary and Al-Fe-Mn ternary intermetallic compounds

with the sequence of Fe-Mn binary intermetallic compounds being the latest

which hardly forms in the interface layer. In regions with a relatively homogeneous Al distribution

the intermetallic compounds exist primarily in the form of Al-Fe binary compounds. In regions with severe Al segregation

such as the welded joint toe

the Gibbs free energies of Al-Fe

Al-Mn

and Al-Fe-Mn intermetallic compounds were similar

leading to a diverse range of intermetallic compounds types.