1. Introduction
2. Experimental Procedure
2.1 Base metal
2.2 Welding preparation
2.3 Hardness test
2.4 Microstructure evaluation
3. Results and Discussion
3.1 VFAW and RSW joints
3.2 Microstructural variations in welds
3.3 Tensile test results
3.4 Fracture energy absorption behavior
4. Conclusions
1) Welds of DP 980 steels were fabricated by VFAW using 8kJ energy input. Alongside, deformed zone of DP980 by VFAW was very narrow only 100~200㎛
2) As a result of the hardness measurement, in RSW occurred HAZ softening and FZ hardening, but in VFAW only hardening occurred in the deformed zone, there was no softening.
3) As a result of microstructure analysis, the fusion zone of RSW was entirely in martensite and the welding zone was created in VFAW, consisting of ferrite and some martensite bands.