Weldability Window Research Articles

Underwater Explosive Welding of Thin Magnesium Plate onto some Metal Plates

Explosive welding of a thin magnesium plate onto some metal plates was performed by using underwater explosive welding technique developed by some of the authors. The experimental results show that the wavy interface which is typically found in the well-bonded clad was observed. The welding condition is discussed using the welding window based on the numerically simulated results using AUTODYN-2D code.

On the formation of a centreline grain boundary during fusion welding

The formation of a centreline grain boundary during fusion welding constitutes a potential weldability issue and its presence may affect the life of a welded structure. In practice, it is therefore often appropriate to avoid it through the choice of suitable welding conditions. A numerical model for the formation of a centreline grain boundary is proposed. It involves the coupling of a semi-analytical heat transfer model and a treatment of dendritic growth in multicomponent alloys. It has been applied to the tungsten–inert gas (TIG) welding of IN718 superalloy. The thermal model and the predicted weld pool shape are validated against experimental observations. A weldability diagram is predicted, on which the conditions for centreline grain boundary formation are identified. The formation of a centreline grain boundary is found to be strongly dependent on welding power, and relatively independent of welding velocity. A weldability window arises if the formation of a centreline grain boundary is to be avoided.

Hot wedge fusion welding of HDPE geomembranes

Double track fusion welding offers more control, produces more consistent welds and is easier to nondestructively test than other types of welding system. However, as with other types of welding, there are a number of parameters which need to be understood and controlled in order to make consistently good welds. Heat, pressure and speed must be properly set, taking into consideration the resin being welded, the thickness of the sheet and environmental conditions. Speed, heat and pressure must be controlled and their effect on weld quality understood. The ‘welding window’ for these variables has distinct boundaries. A test weld which exhibits melting, ‘squeeze-out’ and peels without breaking the liner may not need more pressure or heat. Tests show that for some bonds which peel apart, reducing the heat and/or pressure may be the correct action in order to obtain a film tearing bond (FTB).

An impact weldability domain for the amorphous ribbon/steel system

The explosive welding domain for the amorphous ribbons/steel system is elucidated by the use of gas-gun (impact) welding experiments. The welds obtained inside the weldability window were found to have good bond strength. X-ray diffraction, reflection electron diffraction, and differential scanning calorimetry studies indicate that there is no recrystallisation induced to the amorphous alloys by the temperature generated during the impact.

Testing And Simulation Of Manufacture Of MetalMachine Components Using Explosive Welding

The goal is to study the explosive welding process of manufacturing components of different metals using testings and simulations. In the case study bronze sheets are welded to steels beams to components which are machined into hydrostatically lubricated sliding guides for a highspeed machine frame. Important production variables are explosive substance parameters, detonation rate, geometry of the initial positions and dimensions, material properties and surface preparation parameters. These are used in weldability window models. Qualitative visualisations of the explosive welding are obtained using multibody dynamics program models. It is concluded that the virtual prototype simulations can be used to design optimally the present machine components using the most important design and production variables in explosive welding process. But to get full use of the potential of explosive welding in advanced and conventional applications of geometrically more complex products, more development of virtual prototype simulations from macroto meso-levels is needed. Transactions on the Built Environment vol 32, © 1998 WIT Press, www.witpress.com, ISSN 1743-3509