Abstract
In the present study the microstructund and mechanical properties including high-temperature tensile test of martensitic-ferritic steel 9-12% Cr were assessed. "Ibis steel, which is usually used in gas turbine power plants serving as shroud, was tested in the as-received (virgin) and anificially-aged condition for 1344hrs (8 weeks) at 700 degrees C and the results were compared and analyzed. high-temperature service of this steel suggested investigating the high temperature tensile behavior and the deformation mechanism occurring at different testing temperature and strain rates which were 540, 580 and 620 degrees C and 10(-3), 10(-4) and 10(-5) s(-1), respectively. The results showed that the microstructural features such as phases and carbides are factors which influence the high temperature mechanical properties. The stress- strain rate curves showed a large stress exponent of approximate to 15, indicating that the materials behavior lie in the power law breakdown regime. Based on stress vs. the reciprocal of temperature, the apparent activation energy was calculated as 443 kJ/ Mole. Plotting Zeiler Holloman parameter versus true stress made it possible to mathematically model all test results into a unified model.