Explosion Welding Background
The origins of explosion welding go back to World War II, when it was observed that pieces of shrapnel were not only embedded into armor plating but also being clad, or welded, to the metal. Since there was none of the extreme heat involved in other forms of welding, it was determined that the weld was caused by the explosive forces.
DuPont later applied for a patent on the explosion welding process, which was granted in 1964 and resulted in the use of the Detaclad® trademark. In 1996, DMC acquired DuPont’s Detaclad® operations.
The explosion welding process uses the energy of an explosion to create a weld between metals. The process is most commonly used to clad steel with a thin layer of corrosion-resistant alloy metal, such as stainless steel, brass, nickel, silver, titanium, or zirconium. However, explosion welding can join nearly every kind of metal together. In fact, more than 260 metal combinations are possible.
Although the explosion generates intense heat, there isn’t enough time for the heat to transfer to the metals, so there’s no significant increase in the temperature of the metals. There also aren’t any significant changes in the characteristics of the component metals. The cladding process therefore creates a ductile, high-strength weld over the entire metal surface.
Explosion Welding Process
The explosion welding process begins with only the highest-quality materials from the most reputable manufacturers around the world, that meet our clients’ expectations and our own exacting specifications. Let’s look at the explosion welding of two plates as an example. When two plates are being clad, the mating surfaces of both metals (the surfaces facing each other) are ground flat to achieve a smooth finish and prepare the surfaces for the explosion.
The plates are then ready to be assembled into the pack, which locks the plates into position. To build a pack, the base metal, which is the stronger and thicker of the plates, is laid face up. Then the cladding metal, which is the thinner of the two plates, is placed on top. A small gap is left between the base metal and cladding metal.
Next, explosive powder is evenly spread on the cladding (alloy) plate. The amount and exact formulation of the powder are always matched to the types of metal involved.
The explosion is detonated from one edge of the cladding plate and moves across the top of the pack at a uniform speed, which results in a high-pressure collision of the metals. Oxides and impurities are expelled, leaving the plate surfaces metallurgically pure and creating a metallurgical weld between the two metals.
After this process is performed, the newly formed clad is flattened out by a press or, for thinner clad, a series of rollers known as levelers.
Finally, testing is performed, which involves ultrasonic inspection of the weld, mechanical analysis, and physical measurements to ensure the clad meets customer specifications. After the clad passes inspection, it’s shipped to the customer.