Image Preprocessing Method in Radiographic Inspection for Automatic Detection of Ship Welding Defects

Welding defects must be inspected to verify that the welds meet the requirements of ship welded joints, and in welding defect inspection, among nondestructive inspections, radiographic inspection is widely applied during the production process. To perform nondestructive inspection, the completed weldment must be transported to the nondestructive inspection station, which is expensive; consequently, automation of welding defect detection is required. Recently, at several processing sites of companies, continuous attempts are being made to combine deep learning to detect defects more accurately. Preprocessing for welding defects in radiographic inspection images should be prioritized to automatically detect welding defects using deep learning during radiographic nondestructive inspection. In this study, by analyzing the pixel values, we developed an image preprocessing method that can integrate the defect features. After maximizing the contrast between the defect and background in radiographic through CLAHE (contrast-limited adaptive histogram equalization), denoising (noise removal), thresholding (threshold processing), and concatenation were sequentially performed. The improvement in detection performance due to preprocessing was verified by comparing the results of the application of the algorithm on raw images, typical preprocessed images, and preprocessed images. The mAP for the training data and test data was 84.9% and 51.2% for the preprocessed image learning model, whereas 82.0% and 43.5% for the typical preprocessed image learning model and 78.0%, 40.8% for the raw image learning model. Object detection algorithm technology is developed every year, and the mAP is improving by approximately 3% to 10%. This study achieved a comparable performance improvement by only preprocessing with data.

A Method for Automated Control of Electronic Components on Microfocus X-ray Images

Introduction. Machine vision systems are increasingly used in industrial production, particularly for monitoring the quality of electronic components. Radiographic (Х-ray) inspection is currently one of the most popular types of non-destructive testing. Electronic components are typically characterized by a small size, hence, their radiographic inspection should be based on obtaining images and their further enlargement. X-ray equipment for performing such studies is designed such that there are relatively small input doses of X-ray radiation in the plane of the receiver, which leads to a higher image noise than that using conventional X-ray devices.Aim. To develop a method for automated object recognition on microfocus X-ray images.Materials and methods. A method for segmentation of X-ray images is proposed. In the first step, adaptive median filtering is performed followed by correction of the image background by subtracting the distorting function. Next, the contours of the objects in the image are identified using the Canny edge detector followed by recognition of the objects on the resulting image.Results. The developed method was tested for quality control of the installation of microcircuits and for determining the number of electronic components. The experiments confirmed the accuracy of the proposed method. When monitoring the quality of microcircuit installation, the number of detected defects differed from that verified by the operator by less than 10 %. The average error of the proposed method was less than 0.1% when determining the number of electronic components.Conclusion. The proposed method for object recognition on microfocus X-ray images demonstrated sufficient accuracy in typical tasks of non-destructive testing of electronic components.

Evaluation of TIG dental welding applied to Ti-6Al-4V alloys with different diameters: Analysis by Ultimate Tensile Strength, Vickers Hardness, and Finite Element Method

There is limited information in literature regarding the accomplishment of Ti-6Al-4V TIG joints welded in prefabricated bars applied to dentistry. Evaluate the ultimate tensile strength and Vickers hardness of Ti-6Al-4V alloy subjected to TIG (Tungsten Inert Gas) welding technique in different diameters. Material and methods: Forty-five specimens were prepared and divided into 5 groups: control group (CG) (n=5), with intact bars in a diameter of 3.0mm, and groups TIG2.5, TIG3, TIG4, TIG5 (n=10) with diameters of 2.5, 3, 4 and 5 mm respectively, welded with TIG in a pulse of 10(ms) and in a depth of 3(A). The specimens were tested by both radiographic inspection and penetrating liquids. After that, they were tested by ultimate tensile strength (UTS) and the elongation percentage (EP) was obtained. Images from fractured samples were taken and the welded areas percentage (WAP) was calculated. Random images were also taken by scanning electron microscope (SEM). Vickers hardness was obtained for base metal (BM), Heat affected zone (HAZ) and Welded zone (WZ). Finite element models were constructed. One-way Anova, Dunnet and Tukey tests (α=.05) were used for statistical analysis of UTS, WAP and EP for different groups and for differences in regions (BM, HAZ and WZ). Finite element models were developed in a workbench environment with boundary conditions simulating a tensile test. The majority of the specimens showed internal voids on radiographic inspection, but porosities or groves were not observed on their surface on penetrant liquid test. Most of the samples fractured in the welded area. The 1-way ANOVA showed significant differences among the groups for UTS, WAP and EP values (P<.001). The Dunnett test showed that TIG3, TIG4 and TIG5 groups had lower UTS values than those of the CG, but TIG2.5 group had no statistical difference in relation to CG. The 1-way ANOVA showed significant differences among the regions (P<.001) for Vickers hardness. Under the experimental conditions described, the diameter of 2.5 seems to be the best option for joining prefabricated rods in this kind of union and in this regulation of the machine.

Evaluation of X-shaped welded joints with Co-Cr alloy under different welding parameters: analysis by micro-CT and flexural strength

This study evaluated the mechanical strength correlated to the percentage of the total volume of weld and porosities of Co-Cr alloy joints welded with TIG technique. Thirty specimens were perpendicularly sectioned to the long-axis and rejoined by using X30-shaped joint design with TIG welding. They were divided into 3 groups (n=10): the CG1 with a 60-A depth and 90-ms pulse; the CG2 with a 60-A depth and 120-ms pulse and the CG3 with a 60-A depth and 160-ms pulse. The specimens were submitted to nondestructive tests: radiographic inspection, penetrant liquid and Micro- CT (to calculate the percentage of the total volume of welding and the porosities) and then tested with 3-point bending. The fracture surfaces were analyzed with scanning electron microscopy (SEM). The data were statistically analyzed with 1-way ANOVA and the Tukey post hoc test for all the variables which were analyzed: flexural strength, total volume of weld and porosities. Pearson correlation test was also applied (ɑ=.05). The 1-way ANOVA showed that the factors machine parameters were not significant for flexural strength values (P=.231), the total volume of weld (P=.057) and porosities (P=.057). There are no significant relationships between any pair of variables after Pearson correlation test (P >.050). This, suggesting that the three machine regulation can be an option for joining prefabricated Co-Cr rods in this kind of union.

New NDT Documents in the Field of Nuclear Energy. Radiographic Inspection

The article discusses some inconsistencies in the regulatory documentation for radiographic inspection in the field of atomic energy use. Attention is drawn to differences in permissible values of the heat-affected zone for fillet welds in two regulatory documents NP-105-18 and GOST R 05.05.07-2018, intended for nuclear energy. The pros and cons of selective inspection of joints along the length or quantity are discussed. Possible ways to correct the situation are proposed. It is noted that in GOST R 05.05.07-2018 the approach to calculating images on fittings and nozzles for the first time is explained in a similar way to the calculation when monitoring pipelines through one wall. This is a useful working tool for calculating the number of images, very popular in the practice of inspection

A study of the influence of high frequency cyclic loading on the structure and properties of weld connections in process pipelines

Introduction. Pipeline systems are exposed to several conditions that lead to a drastic reduction in their durability, primarily due to variable low-frequency and high-frequency loads arising in a process pipeline due to the operation of compressor units. Hence, fatigue failure occurs, leading to the pipeline failure. As early as at the pipeline installation stage, sections of process pipelines have weld connections, and thermal welding cycles have an adverse effect on the properties of materials exposed to fatigue loading. The study of weld connections in steel pipelines exposed to high-frequency vibrations and effects of weld seam defects on durability characteristics are the focus of this research. Materials and methods. Low-carbon pipeline steel St20 was selected for the study. The radiographic inspection method, optical metallography, microhardness of structural phases, and the method of high-frequency fatigue tests were used. Results. The results and principal conclusions about the effect of welding defects on durability characteristics of welded samples, made of pipeline steel and exposed to high-frequency fatigue tests, are presented; structural changes in weld connections are analyzed using optical metallography and microhardness methods. Defects of weld seams and their dimensions were identified by means of radiographic inspection. A comparative analysis of durability limits, demonstrated by the parent metal of the model material that has defective weld connections, and the same limits of defect-free samples is provided. The main causes of failure of weld joints, exposed to high-frequency vibrations, are identified. Conclusions. Having summarized the research findings, we can argue that high-frequency vibrations have a negative impact on the parent metal of a process pipeline and its weld joints. The weld seam is the point of failure; defects trigger destruction, and their presence has a higher impact on fatigue characteristics than their dimensions or types. Characteristics of durability in case of exposure to high frequency loading applied to a weld joint in the gigacycle range are 67 percent below those of the parent metal.

Vital pulp therapy: an alternative to root maturation of a tooth with superficial micro abscess

Maintenance of pulp functional integrity should be aimed by the treatment of trauma affected immature permanent teeth. The prognosis of vital pulp therapies (VPT), when well indicated and correctly performed, not only preserves pulp vitality but also provides the immature root development. This case reports the treatment of a patient with a crown fractured immature maxillary right central incisor. Clinical examination, radiographic inspection and sensitivity tests confirmed tooth vitality. In spite of the superficial micro abscess presence, pulpotomy was the treatment of choice according to the pulp vitality characteristics found during the undergoing surgery. Root development and apical closure were verified at the 1st year radiographic control. After 3 years of follow-up, even with the occurrence of 3 new traumatisms, the treated tooth showed radiographic sound characteristics. Nevertheless, on the fourth-year return, the conventional endodontic treatment had to be carried out due to radiographic signal of initial root obliteration. It was concluded that pulp vitality diagnosis step and clinical-radiographic follow-up are extremely important for the pulpotomy outcome. This conservative approach resulted in success since it induced root development and apical closure, permitting the posterior execution of the endodontic therapy.