دانلود رایگان مقاله استفاده از میکرو CT برای آزمایش های غیر مخرب افزودنی تولیدشده جزء تیتانیوم

Abstract

In this paper the application of X-ray microCT to the non-destructive testing of an additive manufactured titanium alloy component of complex geometry is demonstrated. Additive manufacturing of metal components is fast growing and shows great promise, yet these parts may contain defects which affect mechanical properties of the components. In this work a layered form of defect is found by microCT, which would have been very difficult or impossible to detect by other non-destructive testing methods due to the object complexity, defect size and shape and because the pores are entirely contained inside the object and not connected to the surface. Additionally, this test part was subjected to hot isostatic pressing (HIPPING) and subsequently scanned. Comparing before and after scans by alignment of the volumes allows visualization and quantification of the pore size changes. The application of X-ray microCT to additive manufacturing is thus demonstrated in this example to be an ideal combination, especially for process improvements and for high value components.

4. Conclusion

It has been shown that a very specific type of layered defect can be formed in laser AM metal parts, most likely due to imperfect melting in specific layers. These defects are present in a part with as little as 0.005% porosity, but can still be a problem if localized in a thin walled section and is hence of importance in material studies and non-destructive testing of high-performance parts. X-ray microCT seems to be the ideal tool to characterize this type of defect due to the defect size and geometry, though X-ray microCT could also be used to indicate where to physically section a sample for further analysis. The HIP treatment efficiency could be assessed quantitatively and it can be concluded that the treatment is effective for pores smaller than 0.01 mm3 but some larger layered defects can remain almost unchanged possibly due to connection to the surface, but it might be that the flat shape reduces the efficiency of HIP treatment. This visualization and characterization method holds promise for studies of improved material properties from additive manufacturing, and also generally for quality testing of HIPping and other material processing methods.