Study On Small Punch Creep Test Technique

Small punch creep test technique (SPC) using miniature specimen is a newtechnique which is applied to evaluate the creep properties of materials in hightemperature. It is nearly non-destructive and very suitable for the situations in whichtaking conventional sample is impossible or uneconomic. The evaluation of residual lifeof high temperature components can be performed non-destructively. However, most ofthe researches of small punch creep test technique are qualitative and restricted inempirical analysis without support of theoretical knowledge. Also, the SPC test apparatushas varied configurations and accuracies in different laboratories, which greatly affectsthe experimental data. Aimed at the above issues, the experimental research and numerical simulation havebeen performed in this research. Major research works and conclusions are summarizedas follows: (1) A SPC test system of a high accuracy is developed and commissionedsuccessfully. Test data are acquired automatically by a computer. (2) The SPC tests for SUS304 stainless material are carried out in variedtemperatures and loads. Central deflection vs. time and rupture time vs. test load data of aseries of specimen are measured which confirm the compatibility between SPC andconventional creep test and the feasibility of SPC as viewed from the practice. Also, themajor factors influencing the SPC test are discussed in detail. (3) The results of numerical simulation using ABAQUS on SPC show the sametendency between tests and simulation data as well as a little difference and thepracticability of simulation using finite element method for the complicated small punchcreep test. (4) On the basis of the above simulation results, the relationship between specimencentral deflection and central strain is established. Also, the relationship of test load andstress is obtained. So, the problem of calculating central strain of the specimen and stressfrom experimental data is solved. (5) Using the above relationship, the method based on Norton equation achievedfrom SPC test data to evaluate the creep properties of material is suggested anddiscussed.