Research On Fatigue Reliability Of Steel For Pressure Vessel

Destroy of fatigue is universal in modem industry. Though people have paid great attention to the problem of fatigue, there are many accidents recently. Thereby it has been an important subject in modem industrial technique to guide design by method of fatigue analysis. Now, designs of mechanical engineering are changing from traditional method of safety coefficient to the method of combining mechanics analysis with probability analysis. Probability fatigue is a subject that studies the fatigue damage of machine accessory and structure component by the method of probability and statistics and analyzes their fatigue intensity according to the uncertainty and distribution of their fatigue damage. It has shown by the uncertainty of the data of fatigue experimentation and the size deviation of machine accessory and structure component and the original defect of materials that all of the stress and intensity and the factors that affect them are stochastic variables, so we should deal with the problem of fatigue by the method of probability and statistics to making the engineering life deduced by fatigue intensity to be the reliable life under a certain probability.WDL is a certain steel which has lower sensitivity to weld cold crack and need not or a little warm-up before weld. The whole name of this steel is lower weld crack sensitivity steel O7MnCrMoV(shorted as WDL). To study the series WDL steel抯 property of probability fracture mechanics, it is not only the foundation of safety assessment and probability analysis to pressure vessel but also the foundation of the study of assessment criterion on pressure vessel.This paper measures the probability fatigue life of steel WH530 and steel WH6 1 ODL which come from WUHAN steel and iron company and make out their P-S-N curve based on the basic principle of probability fatigue. Study the broad sense description and the estimation of the equation parameter of P-S-N curve. Study the estimation method of the reliability range of the materials fatigue life under given reliability correspond to different stress level.Based on the experiment and theory analysis, we give out the fatigue reliability curve of these two kinds of materials to provide bases for engineering. Get the broad sense method of the materials fatigue reliability according to the basic theory of probability fatigue.