SP creep properties of Gr.91 boiler pipings service-exposed in different USC power plants

Abstract

The small punch (SP) testing technique was applied to five heats of Gr.91 steel, which had been actually used for boiler pipings in different USC power plants for long periods of time to investigate the applicability of this technique to the assessment of heat-to-heat variation of creep property. The experimental results revealed that the SP creep rupture strength and deformation behavior were quite different depending on the heat. Those differences in SP creep property, which could not be evaluated by hardness measurement, were qualitatively similar to those in standard uniaxial creep one. It was expected that the SP creep testing technique was applicable to the assessment of heat-to-heat variation for in-service boiler pipings.

Keywords

• small punch creep test
• usc power plant
• boiler pipings
• heat-to-heat variation
• gr.91 steel