The invention relates to explosion bonded multilayered components which comprise titanium bonded to steel using a copper-nickel interlayer and the method of making the multilayered component.
In the past, it has not been possible to directly join titanium and steel using conventional fusion welding, due to the formation of brittle intermetallics in the weld metal. Explosion bonding has been used to cold weld titanium to steel, however, the bond produced by the direct bonding between steel and titanium does not exhibit good fracture toughness. Thus, if sufficient stress is concentrated in the titanium/steel bond zone to initiate fracture, brittle catastrophic failure of the transition joint can occur. Although this deficiency is not fully understood, the prevailing hypothesis is that the poor bond properties result from a significant atomic spacing mismatch between titanium and steel. U.S. Pat. No. 4,612,259 to Ueda discloses the simultaneous use of two interlayers, first tantalum or niobium, and then copper, nickel, or copper-nickel, between titanium and steel to improve bond toughness of bonded and subsequently hot rolled clad. Both tantalum and niobium are very expensive and limit the practicality of the disclosed product.
Copper and nickel interlayers between titanium and steel have also been used to improve bond toughness. However, the use of copper and nickel does not produce a bond toughness equivalent to that of the tantalum family, and thus the use of either metal is not as effective.
It is therefore an object of the instant invention to provide an improved titanium/steel transition joint with superior bond toughness.
It is a further object of the instant invention to provide a multilayered metal component with improved bond fracture toughness.
It is a further object of the instant invention to provide a method for forming a improved multilayered titanium/steel product utilizing explosive force.