Resistance spot welding has been performed in order to investigate the weld characteristics of boron-containing steel. With heat input increasing, the nugget width increased, which showed a direct proportion to shear tension strength. After welding process, the microstructure of the steels, mainly consisting of martensite in base material, was transformed to ferrite and tempered martensite in HAZ region, while weld zone is chiefly composed of martensite phase due to rapid quenching. The hardness was measured as about 550 Hv at weld zone, and 320 Hv in the region of heat affected zone in spite of 550 Hv of base material. It is deduced that the softening behavior occurred because heat input of welding caused phase transformation of martensite into tempered martensite and ferrite.
All Science Journal Classification (ASJC) codes
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering