A review on friction-based joining of dissimilar aluminum-steel joints

This article showcases details on enumerative information of dissimilar aluminum (Al) to steel welds manufactured using different friction-based welding processes with an emphasis on the description of the manufacturing process, influence of parameters, microstructural variations, formation of intermetallic compounds (IMCs), and variations in mechanical properties. Friction-based welding processes such as friction welding, friction stir welding, hybrid friction stir welding, friction stir spot welding, friction stir spot fusion welding, friction stir scribe welding, friction stir brazing, friction melt bonding, friction stir dovetailing, friction bit joining, friction stir extrusion, and friction stir assisted diffusion welding are analyzed for the formation of dissimilar Al-steel joints. It can be summarized that friction-based joining processes have great potential to obtain sound Al-steel joints. The amount of frictional heat applied decides the type and volume fraction of IMCs that subsequently affects mechanical joint properties. Process variations and novel process parameters can enhance joint properties

Benchmarking Toxic Molecule Classification using Graph Neural Networks and Few Shot Learning

Traditional methods like Graph Convolutional Networks (GCNs) face challenges with limited data and class imbalance, leading to suboptimal performance in graph classification tasks during toxicity prediction of molecules as a whole. To address these issues, we harness the power of Graph Isomorphic Networks, Multi Headed Attention and Free Large-scale Adversarial Augmentation separately on Graphs for precisely capturing the structural data of molecules and their toxicological properties. Additionally, we incorporate Few-Shot Learning to improve the model's generalization with limited annotated samples. Extensive experiments on a diverse toxicology dataset demonstrate that our method achieves an impressive state-of-art AUC-ROC value of 0.816, surpassing the baseline GCN model by 11.4%. This highlights the significance of our proposed methodology and Few Shot Learning in advancing Toxic Molecular Classification, with the potential to enhance drug discovery and environmental risk assessment processes

Exploring Graph Classification Techniques Under Low Data Constraints: A Comprehensive Study

This survey paper presents a brief overview of recent research on graph data augmentation and few-shot learning. It covers various techniques for graph data augmentation, including node and edge perturbation, graph coarsening, and graph generation, as well as the latest developments in few-shot learning, such as meta-learning and model-agnostic meta-learning. The paper explores these areas in depth and delves into further sub classifications. Rule based approaches and learning based approaches are surveyed under graph augmentation techniques. Few-Shot Learning on graphs is also studied in terms of metric learning techniques and optimization-based techniques. In all, this paper provides an extensive array of techniques that can be employed in solving graph processing problems faced in low-data scenarios

Effect of materials positioning on dissimilar modified friction stir clinching between aluminum 5754-O and 2024-T3 sheets

Dissimilar welding in lap joint configuration between AA5754-O and AA2024-T3 materials is successfully performed using novel technique of Modified Friction Stir Clinching (MFSC) process, wherein materials positioning is analyzed in this investigation. The results revealed that materials positioning in dissimilar MFSC between AA2024-T3 and AA5754-O greatly influences joint properties and grain formation behavior in size, shape and orientations. The superior protuberance leveling of keyhole without any defects and with highest fracture load of 1483 N having fascinating mixing features between AA5754-O and AA2024-T3 were obtained when AA2024-T3 material was kept on top of AA5754-O during second phase of MFSC. Dominated ductile fracture characterized as intergranular fracture mode with secondary cracks and quasi cleavage dimples were also observed in both MFSC

Novel manufacturing of multi-material component by hybrid friction stir channeling

The hybrid friction stir channeling (HC) is a recent manufacturing technique, reinforcing the broad range of solutions provided by the technological domain of solid-state friction stir-based welding and processing. HC enables the simultaneous welding of multiple components and the sub-surface channeling within the desired region at the stir zone. HC provides new demanding solutions having free path sub-surface channeling and welding for multi-material components with optimized physical and chemical performances. In the present investigation, a multi-material system consisting of 8 mm thick Al-Mg alloy (AA5083) and 3 mm thick oxygen free copper (Cu-OF) was processed by HC. A specially designed tool consists of the probe’s body features that steer materials extraction and the probe’s tip features that generate materials mixing was applied to produce sub-surface channel at AA5083, along with its simultaneous welding to Cu-OF material. Visual examination of the AA5083′s surface processed by the shoulder, cross-sectional dimensioning, optical 3D scanning of the internal surfaces of the channel, optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, electron backscatter diffraction and micro-hardness measurements were applied to investigate the results. The successful application of HC to manufacture multi-material Al-Cu component is demonstrated. A large sub-surface quasi rectangular channel with 9.6 mm in width per 3.3 mm in height was produced in the AA5083 rib along with defect free welding to thin Cu-OF plate at just below the channel region multi-material. The resulted sub-surface channel was consisted of unique wall surface features, with non-uniform and non-oriented surface roughness, suitable to activate turbulent fluid flow. The microhardness field depicts a higher-strength domain of the stirred material, at the ceiling of the sub-surface channel in comparison with the base materials. The welding zone comprises a metal matrix composite structure with Al-Cu inter-mixing and a mechanical hooking from Cu into the Al matrix. The metallurgical features of the weld stirred zone were analyzed, with an interpretation of Al-Cu phases, and solid solution of Al and Cu in each other. In this zone, Cu-rich lamellae regions are dispersed within the Al-matrix, presenting thin layers of discontinuous intermetallic compounds. The effective potential of manufacturing multi-material component for applicability in thermal management system is demonstrated

Effect of eclampsia on pregnancy outcome at the tertiary care center

Background: Eclampsia is a common medical and life-threatening emergency condition mainly seen in 5-10% of all pregnancies and that is a major cause of maternal and perinatal morbidity and mortality The aim of the study to find out the fetomaternal outcomes of eclampsia in tertiary care hospital and to analyse the trend of eclampsia and associated epidemiological variables.Methods: This retrospective analytical study was undertaken with 40 clinically diagnosed women with eclampsia in their third trimester of pregnancy in the Department of Obstetrics and Gynaecology, at tertiary care hospital from July 2020 to December 2021. Women who came to the hospital with eclampsia or developed eclampsia during hospital stay were included in our study.Results: In our study, the antepartum eclampsia was in 32 cases (80%), primigravida 27 cases (67.5%), maternal age (21-30 years) 26 cases (65%). Cesarean section was the mode of delivery in 26 cases (65%). NICU admission is required by 20 neonates (50%).Conclusions: Eclampsia is an important cause of maternal and perinatal morbidity and mortality. Providing quality antenatal health care services, increasing awareness of patients about warning symptoms, proper investigations, timely delivery, and proper monitoring in the intrapartum and postpartum period have the potential to improve maternal and perinatal outcomes.

Dissimilar friction stir welding of Al to non-Al metallic materials : an overview

The paper presents a comprehensive review on dissimilar friction stir welding (FSW) of Al to non-Al metallic materials, wherein the combination of Al–Mg, Al–Cu, Al-steel and Al–Ti are covered. The summary revealed that FSW is observed as one of the most feasible solutions in the family of welding in case of dissimilar materials combinations of Al to non-Al metallic materials. The challenges such as the formation of intermetallic compounds, defects, and degradation of mechanical properties at the joint area are extensively managed in the case of dissimilar FSW compared to dissimilar conventional welding

Processing and evaluation of dissimilar Al-SS friction welding of pipe configuration : nondestructive inspection, properties, and microstructure

In the present investigation, dissimilar friction welding between AA6063-T6 and SS 304L materials of pipe joint configuration with an outer diameter of 88.90 mm and a wall thickness of 5.4 mm was performed. Four different experimental conditions were varied based on visual inspection after each weld. The welded pipe joints were evaluated by vacuum leak detection, thermal shock test, pneumatic pressure test, tensile test, optical and scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffractions, X-ray elemental mapping, and hardness measurements. The results revealed that friction welded Al-SS bimetallic pipes sustained ultra-high vacuum pressure and cryogenic working environments without leak detection. Al-SS friction welded pipe resulted in high tensile strength with 72% of joint efficiency as compared to AA6063-T6 base material. Microstructure variations were observed significant towards AA6063-T6 material close to the Al-SS interface. The intermetallic compound of Fe3Al phase was identified with a reaction layer between Al-SS joints with varying thickness of 1.1 µm to 2.0 µm