P. C. Hall, Edison Welding Institute, Columbus, OH
Fusion welding Nitinol to stainless steel has historically been very difficult because of a persistent brittle intermetallic phase readily formed by Ti and Fe. This brittle intermetallic phase makes the resulting weld very brittle as well. A method has been developed for making strong, ductile fusion welds through selective weld metal additions that suppress or alter the brittle intermetallic phase. This approach has been demonstrated using an Nd-YAG laser to make wire-to-wire butt weld joints between Nitinol and 316 stainless steel. One target application is the welding of medical guide wires used in vascular intervention procedures for treatment of coronary disease.
Summary: Fusion welding Nitinol to stainless steel has historically been very difficult because of a persistent brittle intermetallic phase readily formed by Ti and Fe. This brittle intermetallic phase makes the resulting weld very brittle as well. A method has been developed for making strong, ductile fusion welds through selective weld metal additions that suppress or alter the brittle intermetallic phase. This approach has been demonstrated using an Nd-YAG laser to make wire-to-wire butt weld joints between Nitinol and 316 stainless steel. One target application is the welding of medical guide wires used in vascular intervention procedures for treatment of coronary disease.
