Research On The Fabrication Method Of Non-Destructive Testing Simulated Test Blocks For Metal Materials

In order to meet the application requirements of simulated defect test blocks in the non-destructive testing field and address the technical difficulties and application pain points,such as the lack of variety in existing preparation methods,low preparation efficiency and effectiveness,difficulty in replicability and large-scale production,and significant differences between the fabricated defects and real defects,this study investigates the application of hot-pressing diffusion bonding(HDB)and selective laser melting(SLM)additive manufacturing techniques in the fabrication of non-destructive testing simulated test block.The main research work is as follows:(1)Application research on fabrication method of hot-pressing diffusion bonding.By conducting experiments,the selected hot-pressing test process parameters were confirmed.Different typical fundamental three-dimensional defects,simulated crack matrix defects,and angular defects were designed as pre-fabricated defect research objects,and the defect fabrication was achieved through specific processes.Different hot-pressing quantitative deformation test conditions were designed and the corresponding simulated test block were fabricated using hot-pressing diffusion bonding method.The macroscopic and microscopic,non-destructive,and destructive analysis methods were employed to analyze and summarize the changes and corresponding conclusions of the test block,defects,diffusion interfaces,and related tissues as technical references.By comparing the hot-pressing diffusion bonding method with other traditional methods for the same designed defect fabrication process and results,the hot-pressing diffusion bonding method was proven to have advantages in terms of scalability,high efficiency,good defect accuracy and repeatability,and suitability for large-sized sample fabrication.(2)Application research of selective laser melting fabrication methodBased on the discrete/accumulation principle of the selective laser melting method,sub-millimeter numerical gradient defects with regular contours were designed as the research objects for forming and fabrication accuracy.The limit fabrication accuracy of this method was determined through non-destructive characterization methods combined with destructive actual verification tests,and the influencing factors and mechanisms of fabrication accuracy were analyzed.The applicability of the selective laser melting method for simulated defect preparation was verified by analyzing the feedback and variation of non-destructive test excitation signals caused by defects.By comparing the selective laser melting method with other traditional methods for the same designed defect fabrication process and results,selective laser melting was proven to have incomparable advantages,especially in terms of the freedom to design defects.Selective laser melting additive manufacturing and hot-pressing diffusion bonding methods complement each other to some extent,and their combination can meet the research and application needs of different size levels of simulated test blocks.(3)Simulation fabrication research of real defectsThe research established and determined the additive manufacturing preparation technology route and related theoretical basis from real defect objects to digital threedimensional models,and then to the reproduction of real defect objects.Several types of typical real defect objects were selected,and the corresponding simulated test blocks were fabricated through the simulation fabrication research using the corresponding technology route.The evaluation process for fabrication conformity and repeatability based on a three-dimensional digital model was researched and determined,and the fabricated simulated defect test block were analyzed and evaluated accordingly.The analysis results showed that the simulated fabricated defects had real defect morphology and good size accuracy,and the fabricated test blocks had high conformity and repeatability.The technical route for simulated fabrication and analysis evaluation of real defects can provide technical references for related research.The digital-based selective laser melting fabrication method,characterized by real defect data,facilitates data storage and on-demand retrieval,providing the foundation for simulated fabrication of real defects at different times and spaces.Real defect data,as the sole input for simulated fabrication,guarantees fabrication conformity and repeatability without being affected by human factors.