The E.O. Paton Electric Welding Institute (PWI) 3D Metalforming NATIONAL ACADEMY OF SCIENCES OF UKRAINE The E.O. Paton Electric Welding Institute (PWI) 3D Metalforming EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 1. Title 2. Speaker Ing. Sergei ILLARIONOV The E.O. Paton Electric Welding Institute (PWI) of NAS of Ukraine Department on Welding, Cutting and Treatment of Metals by Explosion 11 Bozhenko Str., Kiev, 03680, Ukraine Tel./fax: +380-44-205-25-53 E-mail: sergei.illarionov@outlook.com EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Explosive Cladding of Brittle Refractory Metals S.Yu. Illarionov, L.D. Dobrushin, S.D. Ventsev, H.D. Groeneveld

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Re Nb Ta Mo W 3. Subject of our interest EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Considered as refractory metals because of their melting point is more than 2200°C Mo W Subject of our interest They are highly demanded by different high-tech industries as coatings BUT THEY ARE RELATIVE BRITTLE

Low temperature heating prevents crack forming in the interface During several decades explosion welders clad high-strength and brittle materials that tend to crack when explosion loading is applied 4. State of the art EXPLOSIVE CLADDING OF THIN METAL FOILS Low temperature heating prevents crack forming in the interface

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 5. State of the Art EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Friction stir weld in high-strength Al alloy 7010 was destroyed when explosively clad and just with hammer

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 6. State of the art EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Successfully clad at 150°

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 7. Brittle – Ductile Transition EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Some materials, especially metals with body-centered cubic lattice, have relatively narrow brittle-ductile transition temperature range The simplest explanation scheme of brittle-ductile transition effect 1 – Ultimate tensile strength 2 – Yield strength

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 8. Factors influencing on the brittle-ductile transition temperature EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS The brittle-ductile transition temperature is not a constant for certain metal or alloy. It depends on many factors. Stress state Purity Surface roughness Thickness Grain size Deformation velocity

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 9. Plate thickness influence 0.3 mm thickness Mo clad to stainless steel at ambient temperature EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Increasing of the thickness of a cladding plate leads to moving the brittle-ductile transition temperature to the higher values. This can be explained, firstly, by the fact that passage of plastic deformation in the thicker metal is more difficult, especially in the central part of the plate. Secondly, the thicker plate, the higher probability of the presence of rolling defects. These factors impede the movement of dislocations and, consequently, make the metal more brittle Molybdenum Cracks Cracks Copper 1 mm thickness Mo clad to copper at ambient temperature

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 10. Successful realization EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 1 mm thickness molybdenum successfully clad to copper at 60°C

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 11. Successful realization EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 1000 x 600 mm copper-molybdenum plate

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 12. Plate thickness influence EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 0.5 mm thickness tungsten clad to copper at ambient temperature 1 mm thickness tungsten clad to copper at 400°C 0.5 mm thickness tungsten clad to copper at 400°C

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 13. Deformation velocity influence EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Increasing the deformation velocity of a cladding plate leads to moving the brittle-ductile transition temperature to the higher values. The simplified explanation is that increasing deformation velocity leads to increasing dynamic tensile strength and dynamic yield strength. However, the last one grows much faster, so the difference between them decreases. In this case, materials becomes more brittle under explosion loading and higher temperature is required to avoid cracks. Dynamic YS – relative deformation velocity dependence for low carbon steel

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 14. Detonation velocity influence EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 0.5 mm thickness tungsten clad to copper at 400°C when D = 4000 m/s 0.5 mm thickness tungsten clad to copper at 400°C when D = 2000 m/s

EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS 15. Common methodology for finding critical brittle-ductile transition temperature EXPLOSIVE CLADDING OF BRITTLE REFRACTORY METALS Cracking occurs during explosive cladding at ambient temperature Toughness – temperature dependence test procedures at 20…400°C * Making tests above 400°C is not reasonable Explosive welding must be done at the temperature 50…100°C higher than it was found with toughness tests

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