Influence of rolling and heat treatment on the structure and properties of the coatings fabricated on the titanium substrates by electron beam cladding

The influence of rolling and annealing on the structure and properties of VT1-0 titanium with cladded tantalum-containing coatings is estimated. It was found that electron beam treatment contributes to the formation of coatings characterized by the presence of dendritic segregation which is not neutralized by subsequent technological processes. However, the structural investigations revealed that annealing of the rolled material induces transformation of the quenched needlelike structure to the stable one, which is represented by equlaxial grains and lamination. A microhardness level of titanium surface layers after electron beam treatment increased from 165 to 385 HV. Rolling and annealing had no significant effect on the hardness of cladded layers, but they had an impact on hardness of the titanium substrate. Ultimate tensile strength of titanium workpieces after electron beam treatment was approximately equal to tensile strength of commercially pure (cp) titanium (about 420 MPa). Rolling of the composites led to workhardening of the titanium plate and increase of strength up to 610 MPa which was subsequently reduced to about 450 MPa by annealing. Plasticity of investigated materials was lower than plasticity of cp-titanium after all kinds of treatment. Electron beam cladding also induced decreasing the titanium impact strength level to 55 J/cm 2, which decreased to a greater extent (to 40 J/cm 2) after rolling. However, subsequent annealing eliminated the negative effect of technological processes on impact strength of the material and contributed to its increase up to approximately 100 J/cm 2.

electron beam cladding, tantalum, titanium, coating, corrosion resistance