Research On Sampling And Testing Technology Of New Metal Micro-Samples

At present,the development of micro-damage sampling equipment and its follow-up research for pressure vessel and pressure pipeline industry in China is still in the initial stage,and there is no micro-damage sampling machine for pressure vessel industry in China.This paper tries to design a micro-sample sampler which meets the rules of micro-sample sampling,and elaborates the preparation and theoretical analysis of the micro-sample testing technology.The main work is as follows:According to the technical specifications of micro-sampling in China,the basic system and structure of micro-loss sampler are studied,including cutting system,feed system design and cutting rate of micro-loss sampler.According to the design idea,the micro-damage sampler equipment was trial-manufactured and cut.Aiming at the designed micro-damage sampler,the feasibility of actual sampling and the equivalence of mechanical properties of the micro-samples were studied.The research contents include:(1)According to the obtained micro-sample,the thickness of the boundary damage layer of the micro-sample is observed and counted by metallographic analysis,which verifies the superiority and reliability of the sampling effect of the micro-sample sampler.(2)Small punch tests were carried out on micro-specimens and raw materials,and their mechanical properties curves and parameters were compared an d analyzed,which verified the equivalence of mechanical properties of micro-specimens and the feasibility of micro-damage sampler.Small punch testing is a common method of micro-damage testing technology.In order to study the mechanical properties of micro-samples,the preparation of small punch samples by micro-samples was studied.Combining with the size standard of small punch specimen and the precision of wire cutting method,the cutting planning of circular sample for making small punch specimen is studied.By establishing mathematical model,the optimal cutting method and the analytical method of maximum cutting number are determined.In view of the difference in processing thickness of small punch specimen prepared by micro-sample,which leads to the difference of experimental data in the results of traditional correlation method,the relationship between small punch test and traditional tensile test method was explored.Based on literature analysis and theoretical deduction,a set of correlation equation considering the thickness of small punch specimen is obtained by using the test data and data analysis method of small punch of various materials,which provides a new method and theoretical basis for the correlation between small punch test and traditional tensile test.