Study of Weld Hardness of Pipes at Elevated Temperature Application in Power Plants

Weld hardness has close relationship with creep strength and ductility of the welded structures. Hence it is important for any weld to achieve certain level of weld hardness. This study aims at identifying the parameters that affect the quality of weld in achieving the required weld quality in terms of hardness and to establish the relationship between different factors that affect the weld hardness. The focus is to study and explore the welding input parameters for the gas tungsten arc welding (GTAW) of elevated temperature piping used in power plants and to predict the weld hardness on construction sites. The Design of Experiment (DoE) is used in analyzing the related parameters. The data generated through experiments has been validated for the hardness based on input process parameters (welding current, welding voltage, travel speed, welding rod diameter). The findings from the study revealed that the most important factor influencing the hardness of creep-strength enhanced ferritic (CSEF) material welds is the voltage while other factors have minimum or the least influence for the studied ranges and factors.