Correlation Factor Study Of Small Punch Creep Test And Its Life Prediction

Properties evaluation and residual life inspection of the in-service high temperature equipment are of great significance to reduce staff injury and economic losses of the industry.Small punch creep test is one of the innovative methods that can be used to evaluate the properties of material without destructive harm to the in-service component.Conventionally identified material properties by uniaxial test are widely applied to engineering practice.How can the properties obtained from small punch creep test be applied with the same utility has been the goal.In 2006,European Code of Practice(CoP)of small punch creep test was firstly released,in which the correlation factor Ksp was introduced to bridge the gap between the above methods.The author investigates the relationship between uniaxial creep test and small punch creep test by exploring the correlation factor Ksp.Various sets of experiments and comparative studies of the conventional uniaxial creep test and small punch creep test were carried out.Methods include Norton Equation,Dorn equation were employed to determine the value of Kap.At the meanwhile,with the obtained creep rupture data of 16Mo3,by employing the Monkman-Grant and Larson-Miller Parameter life prediction models,the relation between rupture life and loading level of small punch creep test and uniaxial creep test was established.The results achieved are stated as follows:1)A practical approach of determining the correlation factor between small punch creep test and uniaxial creep test was suggested,which is more feasible than the previous commonly used one.2)By conducting various sets of small punch creep tests and uniaxial creep tests,the correlation factors Ksp for three different high temperature materials were derived.With the derived Correlation factor,the data of small punch creep test can be converted into the uniaxial creep results3)The life prediction model of Monkman-Grant and Larson-Miller Parameter were established.By comparing the prediction model of Small Punch Creep test and uniaxial creep test,influence factors of the accuracy were discussed.