The origin of weld seam defects related to metal flow in the hot extrusion of aluminium alloys en AW-6060 and en AW-6082

Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. As these joins occur along the entire extruded length, it is desirable that these weld seams have a minimal impact on the structural integrity of the extrudate. In particular, defects associated with weld seam formation should be avoided. In this...

Towards predictive control of extrusion weld seams: An integrated approach

Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. The formation of longitudinal weld seams is a solid bonding process, controlled by the local conditions in the extrusion die. Being the weakest areas within the extrusion cross section, it is desirable to achieve adequate properties of these weld...

Developing a predictive weld-seam formation model: Experimental support

In hollow aluminium extrusions produced with porthole dies, longitudinal weld-seams are present throughout the entire extruded length, due to rejoining of metal streams inside the extrusion tooling. These weld-seams, formed by a solid-state bonding process at elevated temperatures and under conditions of interfacial pressure and plastic...

An integrated approach for predictive control of extrusion weld seams: Experimental support

In hollow aluminium extrusions, longitudinal weld-seams are formed through a solid-state bonding process at elevated temperatures and under conditions of interfacial pressure and plastic deformation. For structurally loaded components, sound weld seams are imperative. In our research, a weld seam integrity indicator as a means of quantifying...

Constitutive model for aluminum alloys exposed to fire conditions

An existing constitutive model for creep, developed by Dorn and Harmathy, is modified in order to be used for fire-exposed aluminum alloys. Two alloys, 5083-O/H111 and 6060-T66, are selected for the development of this constitutive model because of their different behavior at elevated temperature and their frequent application in structures for...

Combustion synthesis of TiB2-based cermets: modeling and experimental results

TiB2-based cermets are prepared by combustion synthesis followed by a pressing stage in a granulate medium. Products obtained by combustion synthesis are characterized by a large remaining porosity (typically 50%). To produce dense cermets, a subsequent densification step is performed after the combustion process and when the reacted material is...

Shear initiation of Al/MoO3-based reactive materials

Reactive mixtures based on nano aluminium and nano- or micron size molybdenum trioxide have been pressed. These energetic mixtures have been tested in the Ballistic Impact Chamber and as an energetic projectile impacting a steel plate. Al/ MoO3-based reactive mixtures can be initiated by a controlled mechanical stimulus. The sensitivity depends...

Shear initiated reactions in energetic and reactive materials

Deformation of energetic materials may cause undesired reactions and therefore hazardous situations. The deformation of an energetic material and in particular shear deformation is studied in this paper. Understanding of the phenomena leading to shear initiation is not only necessary to explain for example the response of munitions to intrusions...

Experimental study and modelling of combustion front velocity in Ti-2B and TIC-based reactant mixtures

Experiments and numerical modelling of gasless combustion processes (Lecture)

Experiments have been performed to produce TiC and TiB2-based cermets by Self-sustained High temperature Reactions or gasless combustion starting from the pure elements: titanium, carbon and boron and the admixing of inert metallic powders. Experimentally it has been observed, that porosity in the reactant mixture is needed for the reaction...

Functionally graded TiC-based cermets via combustion synthesis and quasi-isostatic pressing

Experimental results on the preparation of functionally graded TiC-based cermets obtained by combustion synthesis (also known as Self-Propagating High-Temperature Synthesis, SHS) followed by quasi-isostatic (QIP) pressing in a granulate medium are presented. Pellets of TiC-Fe graded cermets are produced by stacking layers of Ti and C powder...