Study on Microstructure and Impact Toughness of 1200 MPa High Strength Wear-resistant Steel Weld
1200 MPa high strength wear-resistant steel is an important material used in various engineering applications due to its excellent wear-resistance and high strength. The microstructure and impact toughness of welded steel is significant for its further usage and service performance. This study investigates the microstructure and impact toughness of 1200 MPa high strength wear-resistant steel welded by GTAW (Gas Tungsten Arc Welding) and SMAW (Shielded Metal Arc Welding).
Research Methodology:
GTAW and SMAW welding process was applied on 1200 MPa heat-treated steel plates with 10mm thickness. For microstructure characterization, optical microscope, scanning electron microscope (SEM), and electron backscatter diffraction (EBSD) were used. For impact toughening characterizations, Charpy impact testing method was used.
Results and Discussion:
The weld fusion temperature for GTAW and SMAW was monitored and the turning temperatures for these two welding processes were 1847℃ and 1684℃, respectively. The microstructure observation revealed that while the microstructure of the base metal consists of ferrite and bainite, the fusion zone microstructure of the welds consisted of austenite, ferrite and martensite. The SEM and EBSD characterization also showed that the hardness of the weld beads were slightly lower than that of the base metal. This is due to the lower thermal conductivity of the weld bead and this resulted in lower recrystallization temperature.
The impact toughness results showed that SMAW weld had better impact toughness than GTAW weld. The toughening of SMAW weld was due to its homogenous brittle microstructure with sufficient plastic deformation response.
Conclusion:
This study investigated the microstructure and impact toughness of 1200 MPa heat-treated steel welded by GTAW and SMAW welding processes. The microstructure of the welded steel consisted of austenite, ferrite and martensite. The hardness of the weld bead was slightly lower than that of the base metal. Moreover, the SMAW weld showed better impact toughness than the GTAW weld. Hence, SMAW weld was shown to more suitable for this high strength steel.
Conatct us
