GB1168264A - Explosive Cladding of Metals - Google Patents

Abstract

1,168,264. Welding by pressure. E. I. DU PONT DE NEMOURS & CO. 21 Oct., 1966 [23 Oct., 1965], No. 47380/66. Heading B3R. In explosively cladding a metal backer layer with one or more metal cladding layers, the metal layers are disposed parallel or at an initial angle of less than 10 degrees and the cladding conditions are such that no substantial amount of melt is formed at the interface during cladding. By "no substantial amount of melt" is meant no melt at all or an amount of melt having an equivalent melt thickness of less than 10 microns, this being obtained by dividing the total volumes of alloy by the area of the interface. The equivalent melt thickness is preferably less than 1 micron. There is preferably no diffusion at the interface and a wavy interface having a wave amplitude of at least 5 microns but not more than 50% of the thickness of the thinner layer is preferred. Ordered plastic deformation parallel to the interface is exhibited and any solidified melt is in localized regions spaced between areas of metal-to-metal metallurgical bonding. No substantial melting is obtained when the "collision velocity", i.e. the velocity with which the line or region of collision travels along the layers to be bonded is less than a critical velocity which may be 2300 to 2500 m.p.s., preferably above 1400 m.p.s., e.g. above 1900 m.p.s. The layers may be the same or different and may be alloys. The metals should preferably have a specific gravity of at least 2, e.g. between 4 and 17, especially copper, nickel, iron, silver, titanium, zirconium, tantalum, aluminium, columbium, chromium, cobalt, vanadium, platinum, gold and their alloys. Different metals should preferably have a difference not greater than 9 in their specific gravities. The "impact angle", i.e. the angle between adjacent portions of the layers at the point or line of collision is preferably 7-20 degrees for titanium and 4-18 degrees for nickel. The explosive loading is preferably at least 0À2 and up to 8 times the weight of the cladding layer. A metal base-plate 1 and a cladding plate 2 are spaced in parallel relation by crinkled metal ribbons 4 at the plate corners and the plate 2 is surmounted by granular explosive 5 in a container 6. The explosive is initiated by a blasting cap 7. Mild steel baseplates are clad with nickel plates in this way, the bonding being over more than 90% of the interface, and having equivalent melt thicknesses ranging from less than 1 micron. Mild steel is similarly clad with titanium and the equivalent melt thickness from less than 1 micron. Similarly nickel-copper; tantalumsteel; stainless steel-aluminium; titaniumstainless steel; zirconium-carbon steel and zirconium-stainless steel bonds were effected. In another example a steel plate is clad with a titanium plate, the latter being initially tilted at 4 degrees.