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

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

A novel approach for zero material loss (zero flash) and uniform cross-section during friction stir welding of dissimilar thickness Cu and Al alloys

A novel approach for getting a uniform weld cross-section and flash-free joint with the help of friction stir welding (FSW) is implemented. The influence of the tool tilt angle and rotational speed on the macrostructure, microstructure, and mechanical properties was investigated. Mechanical characterization techniques like an optical microscope, FESEM, profilometer, tensile test, bent test, and XRD analysis were used to evaluate the joint properties. A maximum tensile strength of 108.91 MPa was achieved, which led to a joint efficiency of 96.38 %. A maximum bending angle of 107˚ was achieved for samples S5 and S6. The Al/Cu mixed region in the stir zone displayed a maximum micro-hardness of 152.26 HV whereas a minimum micro-hardness of 33.57 HV was achieved in the HAZ along aluminium side. Welds prepared at a rotational speed of 540 RPM and a tool tilt angle of 4.5˚results in an almost flash-free joint

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

Microstructure evolution and mechanical properties of continuous drive friction welded dissimilar copper-stainless steel pipe joints

In the present investigation, the microstructure evolution and mechanical properties of dissimilar materials Copper-Stainless Steel pipe joints welded by continuous drive friction welding under two different processing conditions are analyzed. The processing conditions of friction welding for copper-stainless steel joints are varied by two friction times of 10 s and 15 s while keeping other processing parameters constant. The welded specimens are analyzed for materials characterizations and mechanical testing using optical microscopy and scanning electron microscopy, electron dispersive x-ray spectroscopy, electron backscatter diffraction analysis, X-ray diffractions, tensile testing, and microhardness measurements. The results revealed that the major microstructural evolution is observed at the Cu side with dynamic recrystallized zones. Enhanced metallurgical bonding between Cu-SS materials is obtained with microstructural evolutions (such as full dynamic recrystallized zone at Cu side and quenching zone at SS side) near to Cu-SS interface, in case of weld made by friction time of 15 s. Superior interatomic diffusion leading to enhanced metallurgical bonding is evidenced for weld made by friction time of 15 s. The reaction layer thickness influences the bonding and mechanical properties of Cu-SS friction welds. The reaction layer thickness of 17.28 μm is observed for the weld made by friction time of 10 s, whereas the reaction layer thickness of 1.21 μm is observed for the weld made by friction time of 15 s. The ultimate tensile strength of 181.05 MPa is obtained for Cu-SS friction weld

Friction welding of dissimilar joints copper-stainless steel pipe consist of 0.06 wall thickness to pipe diameter ratio

This paper examines dissimilar friction welding between electrolytic tough pitch copper (ETP-Cu) and stainless steel (SS) of grade 304 L for pipe joint configuration, having 0.06 wall thickness to pipe diameter ratio. The welding is performed using the continuous drive friction welding method. The welded joint is evaluated by visual inspection, leak-proof ability by helium leak detection testing, microstructure features by optical and scanning electron microscopy, energy dispersive x-ray spectroscope, x-ray diffraction patterns, tensile testing, and hardness measurements. The continuity of welding is evaluated by peripheral inspection and testing on four different locations of pipe welded joint. The results revealed that sound joints between dissimilar materials of Cu-SS are established with evidence of resistance to leak at room temperature and after cryogenic shock test. The Cu-SS pipe joint received excellent strength of 242.48 N/mm2, which is nearly 80% of ETP-Cu base material. The microstructure changes are distinctly observed at the Cu side, whereas no significant microstructure changes are observed at the SS side. The microstructure features are consisting of full dynamic recrystallization zone and partial dynamic recrystallization zone that are identified at the Cu side. However, no adverse effect of microstructure on tensile strength and hardness is observed. The weld continuity in the periphery of pipe configuration is observed at four different locations. A continuous reaction layer at four investigated locations is identified, with the presence of Cu and Fe elements at the joint interface

Repairing of exit-hole in dissimilar Al-Mg friction stir welding : process and microstructural pattern

The exit-hole is one major discontinuities in the friction based processes, where all the volume of the tool's probe is missing with a depth that corresponds to the full thickness of the processed component. This letter presents a new technique to repair the exit-hole of an Al-Mg friction stir welding, without any third body material with inexpensive probeless tooling, inducing forging, stirring, and thermomechanical consolidation of the local spot joint. Intercalated banned type structures with interpenetrating features were achieved. Composite type mixed structure was obtained at repaired zone with a local tensile strength of 159 MPa

Overview of fetomaternal outcome in twin gestation

Background: Twin pregnancy, involving the presence of two fetuses in the uterus, has intrigued humanity across history. Key challenges presented by twin pregnancies include prematurity, low birth weight (LBW), intrauterine growth restriction (IUGR), birth trauma, asphyxia, and congenital anomalies. Preterm delivery poses the most significant risk, contributing to elevated perinatal mortality, neonatal morbidity, and long-term health issues for twins. Methods: Retrospective study at Smt NHL Municipal Medical College analyzed 80 twin pregnancies from July 2022 to January 2024. Data included patient demographics, complications, and neonatal outcomes, informing findings through data analysis. Results: In this study, the majority were under 30 years old (56%) and primigravida (68%), with 48% having a BMI over 30. Common complications included preterm labor (70%), pregnancy-induced hypertension (27.5%), and gestational diabetes (20%). Most twin pregnancies were dichorionic diamniotic (80%). Caesarean section rate was 47.5%. Deliveries mostly occurred between 33-36 weeks gestation, with cephalic-cephalic presentation being most common (40%). Neonatal complications were primarily prematurity (50%), resulting in high NICU admissions (62%) and a neonatal death rate of 13.76%. Conclusions: Multiple pregnancies require early diagnosis and vigilant care to reduce maternal and perinatal risks. Access to skilled healthcare providers and advanced facilities is crucial. Antenatal care must be strengthened for timely referrals. Ultrasonography aids early complication detection. Further advancements and awareness are essential for improved outcomes