The Research On Relationship Of Mechanical Properties And Life Assessment Of12Cr1MoV Steel With Pearlite Spheroidization4-5Degree

The strength, hardness and fatigue resistance of12CrlMoV steel pipe decrease while the steel work under high temperature and high press at long time due to the spheroidization of pearlite, dilution of alloying elements and gathering of carbide, especially as the spheroidization of pearlite realize4-5degree. It is very dangerous for the safe operation of generating units.This work studies the influence factors of the strength, hardness of the12CrlMoV steel through analyzing texture and mechanical properties of12CrlMoV pipe under operation in Gansu province in-service boiler. The effect of the texture on the mechanical properties of12CrlMoV is studied by tests of the steel with4-5degree pearlite spheroidization under long time work at high temperature. Through this the service life planning and run-time supervision of the12CrlMoV steel can be resolved. Moreover, the service life of the12CrlMoV steel with pearlite spheroidization4-5degree is assessed by the tests of creep rupture test.The experimental resulting show that the mechanical properties of12CrlMoV steel decrease as the spheroidization of pearlite increases, however the yield strength, tensile strength and elongation of most specimen are higher than criterion lower limits. The high temperature mechanical properties of the steel mainly realize the requires although the properties decrease under high temperature. The workability and remaining work time of the steel should be verified by other tests. The results show that the degree of the pearlite spheroidization is not the direct influence actor of steel service lifetime. The lifetime is decreased with the increase of the operating pressure and temperature. As the same operating pressure and temperature, the lifetime is decreased with the increase of the external diameter of the pipe.