Investigations on Elasto-Plastic Behaviour of the Boiler Steel Mb 16 at High Temperatures

Synopsis

The elasto-plastic fatigue behaviour of a plain 0.2%-carbon steel for boilers and pressure vessels was investigated under strain-controlled alternating tension-compression at elevated temperatures. By means of a new measurement principle it was possible to realize the strain-controlled alternating stress also for a number of cycles of N > 10⁴. For a number of cycles of N>3 × 10⁴ strain-aging effects at elevated temperatures (T = 300, 400 °C) cause a rise of the fatigue curve. Extrapolation of the fatigue curve to a number of cycles of N =. 10⁷ allowed it to determine a critical value of the fatigue limit which shows a good agreement with the fatigue limit from force-controlled high-cycle investigations.