Properties and Structure of Laser Beam Welded Joints of S700MC Thermomechanically Treated Steel

The article presents the structure and properties of joints welded using a laser beam without a filler metal, made of 10 mm thick thermomechanically treated high yield point S700MC steel. The related non-destructive tests have classified the joints described above as representing the quality level B in accordance with standard 13919-1. The destructive tests have revealed the joint characterised by the tensile strength approximately 5% higher than that of the parent metal. Laser welding without the filler metal increases the content of chemical elements responsible for steel hardening (Ti, Nb), which leads to a weld toughness decrease below the acceptable value of 27 J/cm².