SLOW STRAIN RATE TESTING OF STEEL 14MoV6-3

Slow strain rate test (SSRT) represent a dynamic slowly increasing strain imposed by an external means on uniaxial tension specimen according to ASTM G 129 standard. It is used for relatively rapid screening or comparative evaluation of environmental, processing or metallurgical variables that can affect resistance of material. Testing has been accomplished on low-alloyed boiler steel 14MoV6-3 specimens at elevated temperature 540 °C. Specimens of steel 14MoV6-3 for investigations are taken from the main steamline of Unit 5 Thermal power plant Kakanj. Investigation has included two conditions of the same material 14MoV6-3. The first condition is the material that was not in exploitation at power plant steamline, and the second condition is the material that was in exploitation almost 200.000 working hours at steam temperature 540 °C and pressure 13,5 MPa. As a result of prolonged lifetime of exploited material there is a significant degradation of mechanical properties. In addition to the slow strain rate test, tensile testing at elevated temperature 540 °C with high strain rate and standard strain rate is also performed with the aim to investigate dependence between strain rate and mechanical properties of steel 14MoV6-3. Results of this investigation are given in comparative manner between un-exploited and exploited material.