Determination of the static, dynamic and cyclic properties of the heat affected zone for different steel grades

The material properties of the heat affected zone (HAZ) in welds can significantly differ from the material properties of the base material (BM) due to recrystallization effects during heating and cooling. In this work, the microstructure of the heat affected zones of the low-and high strength steels S355J2, S690QL and S960QL was physically simulated by a Gleeble simulator. The temperature profiles for heating and cooling were taken from in-situ temperature measurements of a MAG welding process. The static and dynamic yield strengths of the simulated HAZ were determined by tensile tests under variable strain rates. The cyclic material properties according to Coffin, Manson and Morrow were determined for the HAZ and for the BM of each steel by strain-and stress controlled fatigue tests. Furthermore, the cyclic stress-strain curve of each HAZ was determined according to Ramberg and Osgood. Due to the lack of data for comparison, two approximation methods were used for the determination of the cyclic material properties and were compared to the investigated ones.