Infrared thermography non-destructive testing technology has been widely used in the defect detection of composite structures due to its advantages, including non-contact operation, rapidity, low cost, and high precision. In this study, a laser-line scanning system combined with an infrared thermography was developed, along with a corresponding dynamic sequence image reconstruction method, enabling rapid localization of surface damages. Then, high-precision quantitative characterization of defect morphology in reconstructed images was achieved by integrating an edge gradient detection algorithm. The reconstruction method was validated through finite element simulations and experimental studies. The results demonstrated that the laser-line scanning thermography effectively enables both rapid localization of surface damages and precise quantitative characterization of their morphology. Experimental measurements of ceramic materials indicate that the relative error in detecting crack width is about 6% when the crack is perpendicular to the scanning direction, and the relative error gradually increases when the angle between the crack and the scanning direction decreases. Additionally, an alumina ceramic plate with micrometer-width cracks is inspected by the continuous laser-line scanning thermography. The morphology detection results are completely consistent with the actual morphology. However, limited by the spatial resolution of the thermal imager in the experiment, the quantitative identification of the crack width cannot be carried out. Finally, the proposed method is also effective for detecting surface damage of wrinkles in ceramic matrix composites. It can localize damage and quantify its geometric features with an average relative error of less than 3%, providing a new approach for health monitoring of large-scale ceramic matrix composite structures.

In order to determine the failure reason for the non-working area of a cracked A-pillar hot-stamping die insert, various instruments were used to detect the properties and microstructures of the cracks and matrix. The results show that the cracks are located in the area where the oxidative corrosion is more serious, and the cracks do not appear in the pitting area, verifying that crack initiation is related to the stress concentration on the upper half of the inner wall of the cooling channel. Meanwhile, pores and cracks exist in the grain boundary and crystal, making the impact energy of the die steel poor. Therefore, crack initiation and propagation easily occur along the brittle oxide layer. In summary, the die insert is damaged by stress-induced corrosion. In engineering applications of hot-stamping dies, we should pay more attention to the cracking of the cooling channel caused by stress and corrosion.

Nanometrology guarantees the dimensional accuracy in nanomanufacturing. As integrated-circuit features shrink progressively, the conventional laser-wavelength traceability system becomes highly susceptible to ambient disturbances and fails to meet in situ production requirements. Referencing a quantized optical-lattice constant, a flattened traceability chain provides higher throughput and enhanced environmental robustness by reducing the number of calibration transfer steps. Its cornerstone is the self-traceable grating. The grating’s pitch is directly traceable to the 7S ₃ →7P ₄ ⁰ transition frequency of chromium (Cr) atoms, which provides picometer accuracy. However, this accuracy is vulnerable to thermal expansion. We developed a thermo-mechanical coupling model to quantify temperature effects and analyze the pitch expansion. This model was validated by finite element simulation (FES). The analysis reveals a cooperative mechanism for stress relief. This mechanism involves interfacial constraints caused by the thermal expansion coefficient (CTE) mismatch between the substrate and the atomic layer. These constraints work in concert with a buffer layer to relieve stress. Within (20 ± 5) °C, the pitch expansion of a 212.78 nm Cr grating decreases from 0.5 to 0.04 pm °C ⁻¹ when silicon substrate is replaced by zero expansion glass. This represents an order-of-magnitude improvement. Pitch expansion scales linearly with buffer layer thickness, albeit with opposite slopes for the two substrates. The proposed model and optimization rules furnish theoretical and engineering guidance for boosting nanometrological precision, and fortifying traceability reliability.

Zn-Ag alloys are deemed extremely promising materials for manufacturing biodegradable medical implants. Nonetheless, their practical applications are still constrained by inferior mechanical properties. To tackle this issue, Zn-0.5Ag alloy was alloyed with Mg (0.2 wt.%) and processed by combined equal-channel angular pressing (ECAP) and rolling, with different rolling reductions (40%, 60%, and 75%). ECAP-processed Zn-0.5Ag-0.2Mg alloy exhibited superior mechanical properties to its as-cast counterpart. Subsequent rolling of 40% further enhances the mechanical performance of ECAP-processed Zn-0.5Ag-0.2Mg alloy, with yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) reaching 255 MPa, 309 MPa, and 52%, respectively, surpassing the application requirements. As the rolling reduction increased to 60% and further to 75%, YS and UTS declined, whereas EL rose continuously. The underlying mechanisms for the variation in strength and ductility were elucidated based on microstructure evolution analysis through optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) characterizations.

4Cr13 martensitic stainless steel is widely used for plastic molds, but welding repair can produce heterogeneous weld/HAZ microstructures and a strength–toughness trade-off. This study evaluates how filler-wire composition and post-weld heat treatment affect the mechanical performance of repaired 4Cr13 steel. TIG welding was performed using high-molybdenum (HM), low-carbon (LC), and base-metal (BM) wires, followed by either post-weld tempering or quenching and tempering. Post-weld quenching and tempering reduced the hardness gradient and improved the overall hardness uniformity. The average weld-metal hardness followed HM > BM > LC, while the BM joint showed the smallest hardness variation because its nominal composition matched that of the base metal. After quenching and tempering, the tensile strengths of the HM, LC, and BM joints reached 1299.5, 1315.6, and 1300.0 MPa, respectively, compared with 1290.8 MPa for the similarly treated base metal. The corresponding impact energies were 58.9, 116.3, and 36.8 J, with LC showing the highest toughness. Fracture observations were consistent with these mechanical-property differences. The results demonstrate that filler-wire composition and post-weld heat-treatment route should be selected jointly according to the required balance of hardness uniformity, strength, ductility, and impact toughness, providing an experimental basis for repair-welding process selection for 4Cr13 steel.