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    ZHANG Tao, TIAN Feng, CHEN Hao, HOU Guo-xin, FENG Ze. Causes Analysis on Rupture of 2Cr12NiMo1W1V Steel Reheat Interceptor Valve Stem of a Ultra-supercritical Turbine[J]. PHYSICAL TESTING AND CHEMICAL ANALYSIS PART A:PHYSICAL TESTING, 2015, 51(4): 278-282.
    Citation: ZHANG Tao, TIAN Feng, CHEN Hao, HOU Guo-xin, FENG Ze. Causes Analysis on Rupture of 2Cr12NiMo1W1V Steel Reheat Interceptor Valve Stem of a Ultra-supercritical Turbine[J]. PHYSICAL TESTING AND CHEMICAL ANALYSIS PART A:PHYSICAL TESTING, 2015, 51(4): 278-282.

    Causes Analysis on Rupture of 2Cr12NiMo1W1V Steel Reheat Interceptor Valve Stem of a Ultra-supercritical Turbine

    • The rupture causes of a 2Cr12NiMo1W1V steel reheat interceptor valve stem of a ultra-supercritical turbine were analyzed by means of macro inspection,chemical compositions analysis,mechanical properties test,optical microscope and scanning electron microscope analysis.The results show that the excessive brittleness of nitriding layer of the valve stem was the main cause for the rupture.Cracks generated in the nitriding layer near exhaust steam holes when the valve stem extruded with the valve disc,then the cracks extended from nitriding layer to the base metal,and finally the valve stem was broken.On the other hand,the valve stem was used in high temperature environment for a long time where the temperature was higher than the designed value,which would reduce the ductility and plasticity and result in creep damage.So the cracks extending velocity was increased and the service life of the valve stem was shorten.
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