The present study describes the effect of FRICTION welding process on mechanical and metallurgical properties of AISI 304 steel. The JOINTs were made by direct drive FRICTION welding (DDFW) machine, while the characteristics of FRICTION welded JOINTs were evaluated by macro-microstructure, microhardness, tensile test with 4 mm and 6 mm effective diameter, and scanning electron microscope (SEM). The results showed severe flash formation at stationary side related to rotating side, highly plastically deformed zone (HPDZ) was revealed at the interface with large dimension of 110 µm. Maximum microhardness values were recorded at welded center and increased from peripheral to central zones. Reducing ratio of ultimate tensile strength (UTS) and ductility for welded JOINT related to AISI 304 were 86 and 67%, respectively. Tensile fractures occurred adjacent to the interface at thermo-mechanically affected zone (TMAZ). Fracture morphologies by SEM were discovered cleavage features and mostly ductile mode with micro-porosities of different forms and dimensions

This study focuses on the effect of FRICTION pressure on the welding JOINT strength of AISI 316. Single factor method was used to evaluate the influence of FRICTION pressure, whilst the other conditions kept constant. The experimental data were achieved by temperature measurement using infrared thermometer and thermometer by touch, where hardness Hv10 and micro-hardness Hv0.1 realized along the axial direction, tensile test specimen with 8 mm effective diameter, scanning electronic microscopy (SEM) to observe tensile fracture surface and x-ray diffraction (XRD) to analyze the concentration of gamma iron. The results by high FRICTION pressure provide increased temperature during FRICTION and forging phase, elevated hardness and micro-hardness values at the welding center, improved ductility and ultimate tensile strength (UTS). Whilst the central region of tensile fracture seemed most ductile mode and presence of micro-porosities with different forms and dimensions, hence concentration of face centered cubic (FCC) structure of gamma iron clearly revealed at level of 111.

Lap JOINTs of commercially pure magnesium plates to aluminium plates (Magnesium plate on the top, and Aluminium plate, grade 1100, on the bottom side) were conducted by FRICTION stir welding using various traveling and rotation speeds of the tool to investigate the effects of the welding parameters on the JOINT characteristics and strength. Defect-free lap JOINTs were obtained in the welding traveling speed range of 40-80 mm/min, and rotational speed range of 1200-1600 rpm. The shear tensile strength of Mg/Al JOINTs increased as a result of decreasing the welding speed from 120 to 40 mm/min at constant rotation speed of 1600 rpm. Defects such as surface grooves, excessive flash, tunnels, and voids were observed if the JOINTs prepared out of the mentioned range. The effects of the welding parameters are discussed metallographically based on observations with optical and scanning electron microscopes.

The current paper presents a robust optimum design of FRICTION stir welding (FSW) lap JOINT AA1100 aluminum alloy sheets using Monte Carlo simulation, NSGA-II and neural network. First, to find the relation between the inputs and outputs a perceptron neural network model was obtained. In this way, results of thirty FRICTION stir welding tests are used for training and testing the neural network. Using such obtained neural network model, for the reliability robust design of the FSW, a multi-objective genetic algorithm is employed. In this way, the statistical moments of the forces, temperature, strength, elongation, micro-hardness of welded zone, grain size and welded zone thickness are considered as the conflicting objectives. The optimization process was followed by multi criteria decision making process, NIP and TOPSIS, to propose optimum points for each of the pin profiles. It is represented that some beneficial design principles are involved in FSW, which were discovered by the proposed optimization process.

Dissimilar metals FRICTION welding of austenitic–martensitic stainless steels is commonly used for manufacturing engine valves in automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) valve steel rods were welded by FRICTION welding. The welded JOINT was then heat treated at 760 ◦C for 60 min. Mechanical properties of the welded and heat treated samples were identified by means of micro-hardness and tensile tests. Microstructure of the weld and the fracture surface of the tension samples were investigated by optical and scanning electron microscopies. Fractographic evaluations were also performed by using scanning electron microscopy. According to the findings, due to the higher thermal conductivity and lower strength of the martensitic stainless steel, a larger upset and a broader heat affected zone are observed in the martensitic side. Furthermore, formation of non-tempered marten site with the maximum hardness of 880 HV in the heat affected zone (HAZ) of the martensitic stainless steel side makes the as-welded material susceptible to brittle fracture as detected by fractographic examinations. Nevertheless, a successful transition from brittle to ductile behavior is observed by the post-weld heat treatment at 760 ◦C for 60 min.

Introduction: Knee Osteoarthritis (OA) is one of the most important etiologies of pain and disability among adults. The effects of pulsed Ultrasound (US) on pain reduction and JOINT function have been proven, but its role on JOINT FRICTION and inflammatory mediators is still unclear. Therefore, this study was designed to investigate the effects of US on knee JOINT FRICTION and inflammation in non-traumatic experimental knee OA. Materials and Methods: Forty-eight guinea pigs were randomly assigned into four groups: OA+US, OA+US sham, 30 days after OA induction (OA30), and normal control (n=12 for each group). OA was induced by intra-articular injection of 3 mg/kg of Mono-Iodoacetate (MIA) in the animal’, s left knee. JOINT circumstance and weight of the animals were measured at baseline, before (i. e., after 30 days of MIA injection), and after US treatment. JOINT FRICTION was evaluated by a pendulum FRICTION tester system. Cytokine levels, including Tumor Necrosis Factor (TNF)-α,and Interleukin (IL)-1β, , were measured by the ELISA method. The Pearson correlation coefficient was calculated to study the relationships between FRICTION and inflammation variables. Results: JOINT circumference was increased in the OA30 group. JOINT FRICTION variables, including exponential curve fitting, cycle number, and FRICTION coefficient, were significantly better in the US group (P<0. 05). TNF-α,and IL-1β,cytokine levels were significantly lower in the US group. A significant positive correlation was observed between JOINT FRICTION indices and TNF-α,and IL-1β,cytokine levels (P<0. 05). Conclusion: US was an effective approach for reducing JOINT FRICTION and inflammation in OA30. Moreover, the relationship between knee JOINT FRICTION and inflammation could help us better understand the etiology, mechanism, and treatment strategies of this disease.

In this study, effects of process parameters of FRICTION Stir Spot Welding were investigated on Al2024T3 which has poor weldability. Several spot welds were performed by the FSSW process on the 2mm aluminium sheets. The effects of main process parameters such as tool Rotational Speed (RS), Normal Plunge Depth (NPD), and Dwell Tim e (DT) on the JOINT strength were investigated. By increasing the tool rotational speed, the JOINT strength increased, consequently. The mean failure load improved 52% when the tool rotational speed increased from 800 rpm to 1120 rpm, whereas increasing th e rotational speed from 1120 to 1600 did not have significant effect on the failure load. The results showed, increasing the normal plunge depth from 1. 5 to 1. 75 millimetre led to an increase in the failure load of spot welds by about 1. 62 times. Also, the 3 seconds dwell time showed higher failure load compared to 2 and 5 seconds dwell time.