Because of the absence of heating, EXW products do not exhibit many of the metallurgical characteristics of fusion-welded,
· THE COMPONENT METALS REMAIN IN THEIR WROUGHT STATES; CONTINUOUS CASE STRUCTURES ARE NOT CREATED.
· THE MICROSTRUCTURES, MECHANICAL PROPERTIES, AND CORROSION PROPERTIES OF THE WROUGHT PARENT COMPONENTS ARE NOT ALTERED FROM APPLICABLE PREBONDING SPECIFICATION REQUIREMENTS.
· THERE ARE NO HEAT-AFFECTED ZONES.
· THERE ARE NO CONTINUOUS-MELT BANDS EXHIBITING MIXED CHEMISTRY.
· THERE IS ALMOST NO DIFFUSION OF ALLOYING ELEMENTS BETWEEN COMPONENTS
- Explosion welding is an effective joining method for virtually any combination of metals.
- The only metallurgical limitation is sufficient ductility and fracture toughness to undergo the rapid deformation of the process without fracture. Generally accepted limits are 10% and 30 J (22 ft · lbf) minimum, respectively
Explosion welding is suitable for joining metals of the same type–for example, steel to steel–as well as metals with substantially different densities, melting points, and/or yield strengths–for example, tantalum to alloy titanium. The process is commonly used to join corrosion-resistant alloys to carbon or alloy steels.
- Explosion welding is appropriate for use over a broad range of sizes. It has been used for joining electronic components of widths less than 0.5 mm (0.020 in.) and for cladding plates up to 5 × 13 m (16 × 40 ft).
- Cladding metal thicknesses can range from 0.025 to 100 mm (0.001 to 4 in.), and base metal thickness can range from 0.025 mm (0.001 in.) to over 1 m (40 in.).
- The size limits are generally mandated by component metal manufacturability and transport requirements.
- Explosion welding is limited to the bonding of flat surfaces or coaxial cylindrical surfaces. It is ideally suited for bonding large, flat areas, as in clad plate manufacture
Bond Zone Morphology:
- Explosion welding is traditionally known for its wavy bond zone morphology. The physics of the wave formation process and its relation to process variables are discussed in the article “Fundamentals of Explosion Welding” in this Volume.
- The EXW bond zone morphology is flat at the low end of the bonding velocity range and transitions to wavy as the velocity is increased. Through proper selection of EXW parameters, the bond zone morphology can be tailored to satisfy product performance requirements.
Interlayers: The physical and mechanical performance requirements of the EXW bond zone are determined by the product application. With some combinations of metals, the required bond zone performance characteristics are best achieved with an interlayer between the two primary metals.