Search results for "Composite"
showing 10 items of 4584 documents
Single block 3D numerical model for linear friction welding of titanium alloy
2018
A two-stage approach for the simulation of Linear Friction Welding is presented. The proposed model, developed using the commercial simulation package DEFORM, is 3D Lagrangian, thermo-mechanically coupled. The first phase of the process was modelled with two distinct workpieces, while the remaining phases were simulated using a single-block model. The Piwnik–Plata criterion was set up and used to determine the shifting from the dual object to the single-block model. The model, validated against experimental temperature measurements, is able to predict the main field variables distributions with varying process parameters. Titanium alpha and beta phases evolution during the whole process has…
Residual stress measurement in innovative friction stir welding processes
2017
In recent years, important innovations have been introduced in Friction Stir Welding (FSW) technology such as, for example, the Laser assisted Friction Stir Welding (LFSW) and in-process Cooled Friction Stir Welding (CFSW). Residual stresses have a fundamental role in welded structures because they affect the way to design the structures, fatigue life, corrosion resistance and many other material properties. Consequently, it is important to investigate the residual stress distribution in FSW where, though the heat input is lower compared to traditional welding techniques, the constraints applied to the parts to weld are more severe. The aim of the present work is to verify the capabilities …
In-process control strategies for friction stir welding of AZ31 sheets with non-uniform thickness
2017
Two different in-process control strategies were developed and compared with the aim to produce AZ31 magnesium alloy joints by friction stir welding on sheet blanks with a non-uniform thickness. To this purpose, sheets with dip or hump zones were welded by either changing the rotational speed or the tool plunging in order to keep constant the value of the vertical force occurring during the welding stage of the process. The influence of the main process parameters on the tool force, the micro- and macromechanical properties, and the joints microstructures in the dip and hump zones were analyzed. The results showed that using the rotational speed change-based approach, the hump zones are sub…
Microstructure and mechanical properties of dissimilar Ti/Nb/Cu/steel laser joints
2020
Abstract The absence of intermetallic phases in Fe/Cu, Cu/Nb and Nb/Ti binary systems opens the possibility to obtain reliable joints between titanium alloys and steels by using a multimaterial copper/niobium insert. Continuous Yb:YAG laser welding of 1 mm thick titanium and 316L stainless steel plates through niobium/copper multimaterial insert was performed. The use of a 100 µm laser beam allowed producing isolated molten zones and thus completely avoiding the formation of brittle intermetallic phases, according to SEM and XRD analysis. The effect of energy per unit length applied to the niobium/copper welds on the mixing process and mechanical properties of the joints was investigated. A…
Assessing the influence of fieldshaper material on magnetic pulse welded interface of Al/Cu joints
2019
Abstract Fieldshaper (FS) is a widely used component in magnetic pulse forming and welding to improve the efficiency of the process. It enables to increase the magnetic pressure experienced by the workpieces during forming and welding. Recent developments in this subject focuses to increase the life time of the fieldshaper and to improve the efficiency by introducing shape optimized designs. In this study, we compare the efficiency of four fieldshapers made of Cuprofor, Siclanic, CuBe2 and Steel. The main focus is given to the effect of material properties while the same geometry was considered for those four fieldshapers. The same welding conditions (discharge voltage of 6kV and air gap of…
AZ31 magnesium alloy recycling through friction stir extrusion process
2015
Friction Stir Extrusion is a novel technique for direct recycling of metal scrap. In the process, a dedicated tool produces both the heat and the pressure to compact and extrude the original raw material, i.e., machining chip, as a consolidated component. A proper fixture was used to carry out an experimental campaign on Friction Stir Extrusion of AZ31 magnesium alloy. Variable tool rotation and extrusion ratio were considered. Appearance of defects and fractures was related to either too high or too low power input. The extruded rods were investigated both from the metallurgical and mechanical points of view. Tensile strength up to 80 % of the parent material was found for the best combina…
Contactless generation of cavitation in high temperature liquid metals and its impact on particle dispersion in solidified iron and steel samples
2021
Abstract A recently developed method for the contactless magnetic generation of cavitation is demonstrated for high-melting-point metals. The approach is based on the floating-zone technique, which is truly contactless and crucible-free as it uses electromagnetic forces. Using this method, ultra-high-temperature ceramic particles, such as TiN, TiB2 and TiC, are admixed in liquid iron and 316L steel. The dispersion and particle refinement caused by cavitation treatment during melting and solidification are investigated. Magnetic fields up to 8 T that correspond to pressure oscillation amplitude of 0.83 MPa are used. The signal emitted by the collapsing bubbles is captured and visualized for …
Linear friction welding of dissimilar AA6082 and AA2011 aluminum alloys: microstructural characterization and design guidelines
2015
This paper presents the results of an experimental and numerical campaign on Linear Friction Welding of dissimilar AA2011-T8 and AA6082-T6 aluminum alloys. Experimental tests were carried out with constant oscillation amplitude and process time. Varying oscillation frequency, interface pressure, specimen geometry and mutual position were used. Grain size measurements, HV tests and EDX analysis were considered to characterize the microstructure of the joints as a function of the input process parameters. A thermal numerical model was utilized to predict the temperature profiles in the joints during the process. The obtained results allowed the identification of four weld categories: sound jo…
Dissimilar titanium/aluminum friction stir welding lap joints by experiments and numerical simulation
2016
Dissimilar lap joints were produced by friction stir welding (FSW) out of Ti6Al4V titanium alloy and AA2024 aluminum alloy sheets. The joints, welded with varying tool rotation and feed rate, were studied by analyzing the maximum shear strength, Vickers microhardness and optical observations. A dedicated numerical model, able to take into account the presence of the two different alloys, was used to highlight the effects of the process parameters on temperature distribution, strain distribution, and material flow. The combined analysis of experimental measurements and numerical predictions allowed explaining the effects of tool rotation and feed rate on the material flow. It was found that …
Ultrasonic Welding of PBT-GF30 (70% Polybutylene Terephthalate + 30% Fiber Glass) and Expanded Polytetrafluoroethylene (e-PTFE)
2021
The ultrasonic welding of polymeric materials is one of the methods often used in practice. However, each couple of material subjected to ultrasonic welding is characterized by different values of technological parameters. Therefore, the main objective of the research presented in this paper is to optimize the parameters for the ultrasonic welding of two materials, namely PBT-GF30 (70% polybutylene terephthalate + 30% fiber glass) and expanded polytetrafluoroethylene (e-PTFE). In this sense, the research was carried out considering a plate-type part made of PBT-GF30, which had a thickness of 2.1 mm, and a membrane-type part made of e-PTFE, with a thickness of 0.3 mm. The condition imposed o…