Layered Composite Materials with Desired Thermal/Electrical Conductivity Produced by Explosive Welding V.M. Ogolikhin, S.D. Shemelin Design & Technology Branch of Lavrentyev Institute of Hydrodynamics SB RAS Tereshkovoi Str., 29, Novosibirsk, , Russia EPNM -2010

Steel-Copper-Steel Composite (three-metal) Copper-steel composite material produced by explosive welding has thermal and electric conductivity close to that of copper and strength parameters close to that of steel. These properties, together with good weldability and machinability of said materials, have stimulated the usage of copper-steel bimetal in manufacturing of main parts and units of electro-heat equipment. In present work the possibility to vary in wide range strength, heat conductivity, and electric conductivity of composite material produced by explosive welding is considered. Three-layered steel-copper-steel plate was chosen as model structure. Stainless steel (0.12%C, 18%Cr, 10%Ni) and copper M1 (technically pure copper) were taken as components. Total thickness of 3-layered material was kept constant and equal to 16 mm.

Samples of three-metal In experiments copper plates of size 600 x 600 x (12…14) mm were clad on both sides by steel plates of size 600 x 600 x (1…2) mm. Amatol/AN mixture with detonation velocity 2400… 2800 m/s was used for explosive welding, collision angle was 9…12 grad. Explosive welding was performed in two steps. After cladding of steel on one side of copper plate annealing of bimetal was made at temperature C to eliminate strengthening of copper. Then cladding of copper plate another side was done. Three composite plates were made: 2 pieces with steel layers thickness 1 mm and copper layer thickness 14 mm, and 1 piece with steel layers thickness 2 mm and copper thickness 12 mm.

Properties of three-metal Table 1. Thermal and electric resistance of used materials: copper M1 (technically pure copper) and stainless steel (0.12%C, 18%Cr, 10%Ni). Properties are given for exploitation temperature C. MaterialSpecific thermal resistance ρ t, (m·K)/W Specific electric resistance ρ e, Ω·m Copper2.89· ·10 -8 Stainless steel39.97· ·10 -8 Thermal and electric resistance of multilayered structure (per cross-section area 1 m2) can be find by formulas: R t = Σ ρ ti ·h i, R e = Σ ρ ei ·h i Results of calculations for three-metal with different steel/copper thickness ratios are given in Table 2. Layer thicknesses (steel-copper- steel), mm Electric resistance, Ω Thermal resistance, K/W Table 2. Three-metal thermal and electrical resistance

Nomogram for three-metal thermal resistance Three-metal thermal resistance, K/W Three-metal thickness, mm steel copper

Nomogram for three-metal electric resistance Three-metal electric resistance, Ω Three-metal thickness, mm steel copper

Samples after tension (left) and tear (right) tests Strength test of three-metal Three types of strength test were performed using test machine CDM-5: tear test, tension test, and bending test.

Method of tear test and results Test sample Test scheme σ, kg/mm 2 Average value 25.42

Results of tension test Test sample Strength average value σ, kg/mm 2

Results of bending test Bending test is performed according to Russian Standart GOST Diameter of cylindrical pilot 15 mm. Fracture of outer (clad) layer begins at bend angle > 55 0

Conclusion The present work has confirmed the possibility of manufacturing by explosive welding layered composite materials on the base of copper and steel, providing wide diapason of thermal and electric conductivity and having satisfactory strength properties. These materials can be successfully used in construction of parts and units of electro-heat equipment. The thickness ratio of layers in three-metal steel-copper-steel can be chosen by designer on a step of equipment design engineering using Thank you for your attention