Ultrasonic Microscopy Research Articles

One Pot Synthesis of Thiopyrimidine Derivatives from Lignin Reproductions by Microwave-Assisted Ultrasonic Microscopy with DFT Description for Clarifying the Mass Spectrum

In this work, an efficient and sustainable procedure for the one-pot synthesis of thiopyrimidine derivatives starting 1,3-diketone cut off β-O-4 lignin precursors to create anticancer agents. Microwave-ultrasonic assisted lignin extract in accessing various heterocyclic precursors such as pyrimidine, pyridine, and thiophene moieties. The results designated the ultrasonic-assisted microwave significantly accelerated synthesis with reduced time. We have diversely prolonged to tight-binding approaches to the electron ionization mass spectrometry with quantum stimulation (DFT/EIMS) to examine electron ionization mass spectra correlated to the experiment. Moreover, DFT/EIMS provides into the mechanism of the reaction of mass spectra trials. It cabins on the fragmentation method to raise the challenging bond breaking and structural rearrangements. The quantum chemical process for effective precursors of a mass spectrum is exactness required and discussed. Foremost fragmentation designs are studied and related to experimental data of the pyrimidin-thione derivatives and their glycosides.

Internal Quality Inspection and Characterization of Casting Billets Based on Ultrasonic Microscopy

Abstract For evaluating the internal quality of casting billets, the low-power experimental and metallographic methods have the disadvantages of the complex process, the small detection range and the destructive evaluation. In addition, the internal defects of the casting billet are analyzed by the one-dimensional waveform and two-dimensional image for the traditional ultrasonic testing, which can not describe directly the three-dimensional spatial information. Hence, a new method is proposed based on ultrasonic microscopy to detect and characterize the internal defection of the casting billet. In this paper, 42CrMo casting billet is regarded as objective, five sets of samples are fabricated by adjusting temperature gradient field and the number of presses. The ultrasonic sequence images of the present samples are achieved by using ultrasonic microscopy, and the spatial distributions, number, and sizes are obtained for the defects of the casting billet by reconstructing the three-dimensional appearance of microdefects to characterize the internal mass of the casting billet. Finally, the effective and accuracy of the proposed method are validated by using metallographic method.

Classification Method of Internal Defects in Metal Materials Based on Ultrasonic Point Cloud Data

Abstract The commonly used methods for analysing defects in metal materials include metallography and scanning electron microscopy(SEM). However, these methods require grinding and polishing of the material surface, which can only obtain the characteristics of material surface defects, making it difficult to effectively detect and characterize internal defects in metal materials. Therefore, a deep neural network model based on ultrasonic point cloud data was proposed in this paper, called the Global and Local Feature Fusion Network (GLFFN), to classify the internal defects in metal materials. Firstly, an ultrasonic microscope was used to perform X-layer scanning on the metal materials, obtaining ultrasonic images at different depths, from which ultrasonic point cloud data was extracted. Based on this, the GLFFN model enhances the classification accuracy of internal defects in metal materials by deep fusion of global and local features of the point cloud. With casting billets as the detection object, which contain three typical internal defects: inclusions, shrinkage cavities, and cracks. The accuracy of the new model for defect classification reached 88.24%, which is superior to the traditional methods, proving the effectiveness of the new model on the classification of internal defects in metal materials.

Enhancing precision of defect 3D reconstruction in metal ultrasonic testing through point cloud completion

During the ultrasound multi-layer focused scanning inspection process, the sequential images characterizing the defect morphology suffer from inter-layer contour information loss, which causes a reduction in the accuracy of defect 3D reconstruction, subsequently leading to errors in the characterization of the defect size and morphology. In order to address the above issues, a new method based on the Attention-based Residual Completion Network (ARC) is proposed for ultrasonic point cloud completion to characterize metal defects. Firstly, the ARC network extracts global contour morphological features and local edge detail features from the ultrasonic point cloud through consecutive residual convolutions. Subsequently, the two sets of features are concatenated and finally fed into a decoder based on self-attention, realizing the reconstruction of lost contour information and enhancing the 3D reconstruction accuracy of defects. In the experiment, an ultrasonic microscope was used to inspect actual steel plates. The internal defects were then completed using the ARC network, and the completion results were compared with the metallographic images of the defects. The experiment results indicated that, after completion, the characterization accuracy of defect morphology and sizes is enhanced by an average of 10.31 %. The ARC network provides a novel method for high-precision 3D characterization of internal defects in metal materials.

Laboratory studies on the mechanical properties of sulphur-based construction material at simulated Martian temperatures

Mars is the next destination for further exploration and the hypothetical establishment of humanity's frontier. However, the planet offers very harsh environmental conditions particularly the very cold temperature in the Martian environment. Knowing that the sulphur-based construction material is perceived as one of the ideal Martian construction materials based on the identified abundant source of sulphur on Mars, its behaviour when subjected to the very cold Martian temperature is yet to be fully clarified. Therefore, this study intends to investigate the behaviour of the Martian sulphur-based construction material subjected to the simulated very cold Martian temperature whilst being compared with the simulated hot Martian temperature. Two mixture compositions of 50/50 and 60/40 comprising of sulphur and Mojave Mars simulant 1 (MMS-1) respectively were fabricated in this study characterising the simulated Martian temperature. The workability at 50 % and 60 % sulphur content was initially investigated. Subsequently, the overall mechanical properties characterising the sulphur content and simulated Martian temperature were investigated via unconfined compression, three-point bending and tensile splitting tests. Necessary factors that influence the overall mechanical properties including the internal structure and microstructural characteristics were also performed via ultrasonic pulse velocity (UPV) and scanning electron microscopy (SEM) respectively. X-ray diffraction (XRD) was also conducted to identify the chemical composition of the end product. The comparisons between this study and other previous related studies within the state-of-the-art Martian sulphur-based construction materials were also outlined. Prospects for future construction on Mars are also presented. It was found that the 60 % sulphur content exhibited higher workability due to the high amount of unreactive sulphur. The 50 % sulphur content recorded the optimal overall mechanical properties under the simulated hot and very cold Martian temperatures. The simulated very cold Martian temperature triggered non-uniform interparticle distribution and larger cavities thus dramatically reducing its overall strength and triggering higher volumetric inconsistency. The very brittle nature of unreactive crystallised sulphur binder at excessive thickness particularly at 60 % sulphur content in between filler particles also triggered volumetric inconsistency which further worsened at the simulated very cold Martian temperature. The iron sulphate hydrate found was almost in agreement with the related works and another new compound, potassium calcium magnesium sulphate was identified as well. The overall mechanical properties are comparable with the other previous related studies and the residual strength when subjected to the simulated very cold Martian temperature remains adequate in the Martian environment of low gravity. The 60 % sulphur content is suggested for structural elements built internally whereas the 50 % sulphur content demonstrated a high potential in adapting to the harsh Martian environmental conditions. The findings of this study hoped to act as the initial outlook on how such Martian sulphur-based construction material would react upon fabrication on Mars.

Study of Demographic Patterns and Treatment Approaches of Ocular Surface Squamous Neoplasia in a Tertiary Care Centre

Abstract Background: Ocular surface squamous neoplasia (OSSN) includes a wide spectrum of conjunctival and corneal intraepithelial neoplasia, which can manifest as mild, moderate, severe dysplasia, carcinoma-in-situ and invasive squamous cell carcinoma. OSSN can mimic many common indolent lesions like pterygium and have a potential for causing ocular and systemic morbidity and mortality. OSSN is more common in elderly males. ultraviolet-B light, human immune deficiency, and human papilloma virus have been proposed as major risk factors in aetiopathogenesis. Though diagnosis of OSSN is mainly based on clinical suspicion, definitive diagnosis needs histopathological evaluation. Anterior segment optical coherence tomography, ultrasonic bio microscopy, and impression cytology are nonsurgical tools used for diagnosis and management, of which anterior segment optical coherence tomography has brought about a paradigm shift in the diagnosis of OSSN. Aim: The aim of the study was to demonstrate the demographics, clinical profile, types of OSSN, management approaches, histopathology and the effectiveness of different approaches in patients with OSSN in a tertiary care centre in Tamil Nadu. Materials and Methods: It was a hospital-based prospective interventional study where 51 eyes of 50 patients with clinically suspicious OSSN were studied between July 2021 and January 2023 (over 18 months) with a minimum follow-up of 6 months. Results: The age group for the patients ranged between 30 and 79 years. Out of 50 patients, 26 were men and 24 were women with no sex predilection in our study. Unilateral involvement was seen in 49 patients and only one patient had bilateral involvement. Twenty-nine patients presented with gelatinous-like lesions, six with leukoplakic lesions, five with papilliform like lesion, nine with pigmented lesions and one with nodulo ulcerative type lesion. On histopathological examination, majority (21 patients) were severe dysplasia. Majority (78.4%) underwent surgical clearance with no recurrence. Adjunctive therapy to reduce recurrence included intraoperative cryotherapy and postoperative topical chemotherapy using mitomycin C. Conclusion: In our series, the most common morphological type of lesion was gelatinous, and surgical management using Shield’s technique was commonly used as the management option for unifocal lesions less than 5 mm with less than 4 clock hours involvement. The demographic profile was comparable with other studies on OSSN. Being a potentially malignant condition, a study on OSSN helps us in understanding the disease better and helps in early detection, leading to timely intervention and improved treatment outcomes. Furthermore, research on OSSN contributes to enhancing our knowledge on ocular oncology.

Study on the Preparation and Process Parameter-Mechanical Property Relationships of Carbon Fiber Fabric Reinforced Poly(Ether Ether Ketone) Thermoplastic Composites.

Carbon fiber fabric-reinforced poly(ether ether ketone) (CFF-PEEK) composites exhibit exceptional mechanical properties, and their flexibility and conformability make them a promising alternative to traditional prepregs. However, the formation of the CFF-PEEK composite is trapped in the high viscosity of PEEK, the smooth surface, and tightly interwoven bundles of CFF. It is more difficult for the resin to flow through the fibers of complex textile structures. Here, a simple film stacking method using the hot-pressing process of plain-woven CFF-PEEK thermoplastic composites is discussed. The uniform distribution of PEEK resin between each layer of CFF reduces the flow distance during the molding process, preventing defects in the composite material effectively. Four process parameters, including molding temperature (370, 385, 400, and 415 °C), molding pressure (1, 2, 4, 8, and 10 MPa), molding time (10, 20, 30, 40, 60, and 90 min), and pre-compaction process, are considered. Interlaminar shear strength (ILSS), tensile strength, and flexural strength of CFF/PEEK composites are evaluated to optimize the process parameters. Moreover, ultrasonic scanning microscopy and scanning electron microscopy are employed to observe the formation quality and microscopic failure modes of CFF/PEEK composites, respectively. The ultimate process parameters are a molding temperature of 410 °C, molding pressure of 10 MPa, molding time of 60 min, and the need for the pre-compaction process. Under the best process parameters, the ILSS is 62.5 MPa, the flexural strength is 754.4 MPa, and the tensile strength is 796.1 MPa. This work provides valuable insight for studying the process parameters of fiber fabric-reinforced thermoplastic polymer composites and revealing their impact on mechanical properties.

Characterization of the collagen network of human cheek skin using ultrasonic microscopy

Dermal collagen is the most abundant component of human skin and has a network structure that regulates the mechanical properties of the skin. Therefore, non-invasive characterization of the collagen network would be beneficial for the evaluation of skin conditions. The microscopic substructures of the network, which are individual bundles and fibers, have been optically investigated. However, the macroscopic structure of the collagen network has not been assessed. To evaluate the dermal collagen network, we developed two new indicators, volume filling factor (VFF) and collagen fiber texture (CFT), to analyze three-dimensional echo intensity maps of high-frequency ultrasonic microscopy. By identifying the difference in the elastic modulus components of the dermal layer of facial skin, the density and texture of the collagen network were characterized using VFF and CFT, respectively. These new indicators revealed that the density decreased and the texture became fine with facial age. This study demonstrates that ultrasonic microscopy is useful for investigating skin conditions, paving the way for diagnostic applications in dermatology and aesthetic medicine.

Residual life prediction of multi-layer composite coatings based on vector quantised and attention-variational AutoEncoder network

ABSTRACT The quality of multi-layer composite coatings (MLCC) directly affects the reliability of equipment. Ultrasonic C-scan has advantages of non-destructive and high-precision. The accurate determination of residual life (RL) from C-scan images of coatings is hindered by the difficulty of feature extraction. To address this issue, a RL prediction method for MLCC based on the Vector Quantised and Attention-Variational AutoEncoder (VQA-VAE) network is proposed. First, by incorporating attention mechanism and residual module, the VQA-VAE network can perform unsupervised feature extraction on C-scan images effectively. Then, the features are fused by two-dimensional entropy weighting method to get the health index (HI), which can be used to establish the RL prediction model. To verify the effectiveness of this method, C-scan is performed on MLCC by ultrasonic microscope to obtain C-scan images, and RL of MLCC is predicted. The experiment results demonstrate that this method achieves higher accuracy in predicting RL of MLCC. In a word, this is a non-destructive, high-efficiency, high-precision, and large-scale measurement technique for MLCC.

Effects of Deformation Penetration and Recrystallization on the Internal Quality of Casting Ingot

To investigate the influence of rolling passes on the internal quality during high‐temperature reduction pretreatment (HTRP), three cast ingots with identical total reduction but varying numbers of rolling passes are prepared. The 3D distribution, size, and quantity of defects are analyzed using ultrasonic nondestructive microscopy. The effect of rolling passes on defect healing is studied, with macrostructure, microstructure, and grain size analysis aided by finite element software. In contrast to the three‐pass HTRP, the one‐pass HTRP demonstrates a diminishment of 7% in defect dimensions and a notable decline of 66% in the quantity of defects. The results reveal that increasing the number of rolling passes leads to a deterioration in internal quality of the slab. Reducing the number of rolling passes improves internal strain penetration, facilitates the recrystallization process, and enhances the microstructure uniformity, ultimately improving the internal quality.

Assessing the Influence of Banana Leaf Ash as Pozzolanic Material for the Production of Green Concrete: A Mechanical and Microstructural Evaluation.

This paper reports an investigation of the mechanical and microscopic properties of partially replaced banana leaf ash (BLA) concrete. In this research, the cement was partially replaced by BLA in two phases: Phase A (0%, 5%, 10%, 15%, 20%, 25% and 30%) and Phase B (0%, 10%, 20% and 30%). The consequence of partially replacing cement with BLA in concrete was investigated by the application of a range of tests, namely X-ray fluorescence (XRF), compressive strength, splitting tensile strength, flexure strength, ultrasonic pulse velocity and scanning electron microscopy (SEM) analysis. The properties were then correlated with the properties of a standard 100% Portland cement concrete of similar strength. The XRF result of the BLA identified a composition with 48.93% SiO2 and 3.48% Al2O3, which indicates that the material potentially possesses pozzolanic properties. The mechanical properties of the partially replaced BLA concrete noted minor strength loss, approximately 5% with 20% partial replacement. The nondestructive testing data showed enhanced performance up to 20% partial replacement, with ultrasonic pulse values above 3500 m/s. The scanning electron microscopy analysis illustrated that the morphology of BLA specimens contained increased microcracks compared with the control. The decrease in strength observed is attributed to the fibrous composition of the BLA. The mechanical, nondestructive testing and microscopic results highlight the potential to utilize BLA as a partial replacement for cement as a pozzolanic material in concrete at up to 20% by weight of cement.

Effect of ageing conditions on the low velocity impact behavior and damage characteristics of aramid-basalt/epoxy hybrid interply composites

Polymer composites reinforced with aramid and basalt fibres are widely used in aviation, automobile, marine and civil structural components. In these applications, composites are often exposed to different environments involving temperature and humidity, which leads to the deterioration of mechanical properties and service life of the structure. This study aimed at investigating the influence of different ageing conditions on the low velocity impact (LVI) performance of 2-D aramid-basalt/epoxy interply composites. Compression molding method of fabrication was employed to prepare the hybrid laminates. LVI coupons were made as per the ASTM D3763 standard and aged in distilled water medium at three different temperatures namely, ambient condition (25 ℃), sub-zero condition (−10 ℃), and humid condition (40 ℃ and 60% relative humidity) until the specimens attain moisture saturation. After ageing, specimens were put through low velocity impact testing at two different impact energies of 10 J and 15 J and results were compared with the pristine specimens. Ultrasonic C-Scan and Scanning Electron Microscopy (SEM) were utilized to analyse the delamination due to impact and micro structural assessment of the pristine and aged specimens. Studies revealed that, specimens aged under sub-zero conditions showed better impact response compared to all other ageing conditions. Furthermore, fibre rupture, matrix decomposition, weakened fibre–matrix interface bonding and delamination were the major damages observed in aged specimens.

Photoacoustic (532 and 1064 nm) and ultrasonic coscanning microscopy for in vivo imaging on small animals: A productized strategy.

Photoacoustic microscopy provides a new dimension of observation in microscopic life science. However, due to the high complexity of building a photoacoustic microscopy system, for many life science practitioners, it usually takes several years to build a stable photoacoustic microscopy system. For the above situation, in this article, a productized strategy of photoacoustic (532 and 1064 nm) and ultrasonic coscanning microscopy for in vivo imaging on small animals is presented. A 532 nm laser is applied to image blood vessels and pigments in label-free manner, whereas 1064 nm laser is applied to image pigments and some novel probes developed for NIR-II windows. Ultrasound is applied to assist photoacoustic imaging to accurately locate its imaging site in tissues. All 3D results are obtained with one single scan. The strategy presented here will help life science practitioners to build a stable photoacoustic microscopy platform.

ICL Postimplantation Decentration and Tilt in Myopic Patients with Primary Iridociliary Cysts.

To observe the decentration and tilt of implantable collamer lens (ICL) as well as possible visual effects postimplantation in primary iridociliary cysts. The present investigation was a retrospective cohort study. All 48 patients (91 eyes) who underwent ICL surgery at the Center of Refraction Surgery of Tianjin Medical University Eye Hospital between July 2018 and May 2020 were split into two groups based on the absence or presence of primary iridociliary cysts established by ultrasonic biological microscopy (UBM) examination. Intraocular pressure (IOP), corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), anterior chamber angle (ACA), anterior chamber volume (ACV), and anterior chamber depth (ACD) were recorded preoperatively and postoperatively at 1, 6, and 12 months. Additionally, we performed an analysis of the ICL vault, decentration, and tilt using a rotating Scheimpflug Oculus Pentacam camera system at 1, 6, and 12 months after surgery. No serious complications were observed. Significant postoperative improvement (P < 0.05) of UDVA was established in the two studied groups; however, we did not observe statistically significant intergroup differences (P > 0.05) throughout the entire research period. In each group, the preoperative ACA, ACV, and ACD were statistically significantly reduced (P < 0.05), but no such decrease was established between their postoperative values (P > 0.05). We observed no statistical differences between both groups with regard to their values of IOP, ACA, ACV, ACD, ICL vault, ICL decentration, and tilt at 1, 6, and 12 months after surgery. Similarly, no statistically significant within-group correlation (P > 0.05) of the decentration of ICL and the tilt and the CDVA values was established. No postimplantation effect of ICL with a central hole on vision was established in myopia patients with primary iridociliary cysts, within certain limits of ICL decentration and tilt values.

Effects of Styrene Butadiene rubber on the properties of Normal Concrete

This work titled “examining the effects of Styrene butadiene rubber latex on properties of normal concrete” is aimed at exploring the potential in the use of SBR latex in concrete to investigate how different properties of concrete can be improved. Styrene Butadiene Rubber Latex with brand name “Top Shield” was added by virtue of volume of cement in the concrete mix in percentages of 0, 5, 10, 15 and 20%. A total of 135 samples consisting of 45 pieces of 150mm*150mm*150mm cubes, 45 samples 100*100*500mm beams and 45 pieces of 200mm*10mm diameter cyl-inders were cast. A concrete mix design using ACI was used targeting a strength of 25N/mm2 and a mix ratio of 1:2.4:2.6 was used at a constant water cement ratio of 0.44 adopted. Samples were cured for 3, 7, 28 days. Samples were tested to investigate different properties of concrete test through slump, compressive strength, flexural strength, split tensile strength, water absorption, ultrasonic pulse velocity and scanning electron microscopy tests were conducted on the samples. Regression analysis of result was conducted using excel multiple regression tool and mathematical formulae were developed to help field workers and researchers forecast the degree of certain properties of interest and to determine how each variable affect the end result. Results showed positive improvement in all properties tested for. Preliminary quality control tests were carried out on the respective ingredients of concrete to determine their suitability with reference to ASTM Standard. The study recommended that further research should consider the use of a higher percentage of SBR latex to find the optimum compressive and tensile properties of the concrete.

Characteristics of TiN Thin Films Deposited by Substrate Temperature Variables Using Scanning Acoustic Microscopy

In this study, TiN thin films fabricated based on the substrate temperature process parameters of a DC magnetron sputtering device and their characteristics are analyzed. TiN thin films are deposited on Si wafer (100) substrates by setting the substrate temperatures to ambient temperature, 100, 200, and 300 °C. The residual stress measurement using the XRD method, adhesion characteristic analysis performed using a nanoscratch test to measure the critical load of the nanoindentation device, and leaky surface acoustic wave (LSAW) measurement were conducted using the V(z) technique of the ultrasonic microscope; the correlations between each measurement were analyzed. The residual stress of the TiN thin film was relieved by up to approximately 48% and adhesion properties enhanced by approximately 10% with an increase in the substrate temperature. In addition, the velocity of the LSAW presented a tendency to increase by up to approximately 5%. The residual stress and velocity of the LSAW were found to be inversely proportional, while the critical load and velocity of the LSAW were directly proportional.

Effects of sodium nitrate and OPC-GGBS concrete mix composition on phase transition of pore water at subzero temperatures

Lowering the freezing temperature of the mixing water is crucial for concrete works at subzero temperatures. In this study, formation of ice was examined for various pastes and concretes of OPC-GGBS based, while exposed to a constant temperature of −15 °C. Sodium nitrate antifreeze admixture was added as 0, 6, 10, 15, 20, 25, 30 wt% by the total binder amount. The ice formation and its effects on the binder matrix microstructure was studied using differential scanning calorimetry (DSC), ultrasonic pulse velocity (UPV) and Scanning Electron Microscopy – Energy Dispersive Spectrometry (SEM-EDS). Several curing procedures were applied to samples before commencing tests. Results showed that, addition of 25 wt% of the sodium nitrate caused the most extensive delay of the ice growth. Mixes containing less admixture showed an increasing amount of the forming ice which in some cases lead to the development of the false strength. The hydration rate has been the highest for the mix with 25 wt% of the sodium nitrate and tended to be limited at lower additions. The porosity of the hydrated binder matrix tended to be lower for mixes characterized by a lower amount of the forming ice. In general, application of above freezing temperature resulted in resuming of the hydration process that led to densification of the microstructure and strength increase. This trend was more pronounced for mixes having lower amounts of the formed ice.

Experimental study on temporary fastening damage of composite structures

An experimental investigation was conducted to determine the form and characteristics of damage that temporary fasteners may cause to the composite hole in the aviation temporary fastening process. According to the shapes of the temporary fastener clamping feet, copying indenters were designed. The similarity between the quasi-static indentation (QSI) experiment and the installation of temporary fasteners was discussed. The QSI experiment was used to investigate the influence of shapes of clamping feet, prepreg category, installation direction, and other factors on the failure of the composite hole, and the displacement-load curves were obtained. The damage morphology was observed with the optical microscope and ultrasonic microscope. The results show that the QSI experiment can simulate the temporary fastening damage well. Due to the expansion of delamination, and the final occurrence of fiber breakage in the composite hole, the bearing capacity is reduced. The temporary fastening damage process can be divided into three stages: in the elastic stage, the laminate does not suffer damage, and the surface resin appears slight dents; in the delamination stage, the layers delaminate at the edge of the contact surface, and expand in the direction of fiber; in the failure stage, sudden damage occurs suddenly under the indenter, and the fiber matrix is crushed into powder. The propagation range of the damage depends on the material properties and installation direction. Compared with T700/3234, T800/X850 has greater energy absorption before the damage. Laminates have the worst anti-intrusion ability out-of-plane in the surface fiber direction. These results increase the understanding of the out-of-plane compression damage of the composite material and provide a theoretical basis and method guidance for the control of the temporary fastening damage of the composite structures. The copying indenter designed in this paper can be used for further research on temporary fastening damage.

Examining the role of water vapor on small fatigue crack growth behavior in Ti-6242S using ultrasonic fatigue and scanning electron microscopy

The influence of water vapor on small fatigue crack growth rates in the near alpha titanium alloy Ti-6242S was investigated using a combined ultrasonic fatigue/environmental scanning electron microscope system (UF-SEM). Small fatigue cracks were grown at a cyclic frequency of 20 kHz in laboratory air, partial pressures of water vapor ranging from 65 to 1330 Pa, and vacuum (1.7 × 10-4 Pa). Fatigue cracks grew at higher rates in all water vapor pressures investigated versus in vacuum, with a nearly identical growth rate observed in laboratory air and 1330 Pa water vapor. A linear dependence of small fatigue crack growth rate on water vapor pressure was observed that is consistent with a pressure dependent transport rate of water vapor molecules to the crack-tip. This work indicates that the amount of water vapor present in the environment (humidity) plays an important role in determining the fatigue life of Ti-6242S and must be accounted for even at very high cyclic frequencies, such as the 20 kHz cyclic frequency commonly employed in ultrasonic fatigue testing.

Quantifying the Comprehensive Characteristics of Inclusion-Induced Defects Using an Integrated Destructive and Non-Destructive Method.

Driven by the continuous improvement of the mechanical properties, especially the fatigue property of the high-strength steels, it is particularly important to characterize the type, size, and distribution of inclusions and the critical inclusions in the steel matrix, as they are decisive for the fatigue life performance. This paper presents an integrated approach for the comprehensive characterization of the inclusions in metals by combining the advantages of destructive methods based on metallography and non-destructive testing methods using ultrasonic detection technology. The position and size of inclusions were obtained by scanning ultrasonic microscope, and the composition and micro-image of inclusions were further analyzed by scanning electron microscope. According to the results obtained by the proposed approach, the distribution laws of oxide inclusions and sulfide inclusions in the samples were statistically analyzed, and then the maximum distribution analysis method was used to predict the maximum inclusions. We compare the predicted size value with the value obtained by the characterization method to establish a certain corresponding relationship. The results show that large defects in metals can be accurately characterized by the proposed method, and the size of inclusions predicted by extreme value analysis is close to that of the scanning electron microscope. The integrated destructive and non-destructive method can reveal the in situ information of inclusions and give the possible relationship between inclusions and process and material properties.