Understanding hot workability of power plant P92 creep resistant steels using dynamic material modelling (DMM) and microstructural evolution

Abstract

Abstract This study reports the hot workability of two P92 creep-resistant steels with different chromium and tungsten contents, all within the ASME specification. These steels are used in manufacturing modern power plant boiler pipes. Uniaxial compression tests were done using a Gleeble® 3500 thermal-mechanical equipment. The test conditions were: deformation temperature of 850–1000°C and strain rate of 0.1-10s− 1. Experimental flow stress values obtained from isothermal hot compression tests were used to construct processing maps employing the dynamic material model approach. The flow stress-strain curve results of the two steels exhibited dynamic recovery characteristics. The flow stress increased with a decrease in temperature or an increase in strain rate. The correlation between the processing maps and the microstructure of the deformed samples reveals that the optimal processing window for the two steels occurred at a deformation temperature of 850°C and 1000°C and a lower strain rate of 0.1s− 1 for the conditions studied. These regions had maximum power efficiency of 26% (P92-A steel) and 19% (P92-B steel). The findings from this study have provided a new approach to process parameter optimisation using a dynamic material model technique of industrial metal forming of P92 steels. Hence, reducing manufacturing time and cost.