Mechanical properties and microstructure of flash-butt CT-90 steel weldet joint

The present work reports new results about developments in the flash butt welding of CT-90 (Coiled Tubing-90) steel. In this study, the flash-butt welding process, microstructures and mechanical properties of the weldet joint are investigated. The main findings are as follows: upset current has a significant effect on microstructures and the mechanical properties of a welded joint. When the upset current value is 357.9 A, polygonal ferrite and pearlite occur in the weld metal, and the mechanical properties of joint are at their best with a yield strength (YS) in the joint of 635 MPa, ultimate tensile strength (UTS) of the joint at 706 MPa, impact-absorbed energy of the weld at 112 J × cm , and with the impact-absorbed energy of the heat affected zone at 166 J × cm