| Explosive welding technology can make different cladding metals achieve a bonding metallurgical combine using the very high pressure and high speed impact energy instantaneously produced by explosive.And more excellent comprehensive properties will be achieved with the next machining and heat treatment.Hastelloy/Q345R explosive composite plate belongs to layer-metal composites with the advantages of high bonding strength and good corrosion resistance,which can requires the particular application in the fields such as military industry,shipbuilding.A high-performance Hastelloy/Q345R explosive composite plate produced by Xi'an Tianli Composite Materials Company using patent technology is chosen as the research object.The paper studies the influence of annealing heat treatment on the microstructure of the composite plate and interface bonding effect,discusses the mechanism of wave formation and analysis the diffusion phenomenon among elements in bonding interface during heat treatment.The correlation among microstructure,phase structure constitution and mechanical property is investigated by means of microhardness test and tensile shearing test.According to the study of electrochemical properties in the bonding interface,the factors influencing corrosion resistance of the composite plate are cleared.Some valuable conclusions are as following.The results of microstructure observation by means of optical microscopy show that the bonding interface belongs to the pattern of big wave combination,with the characteristics of wave front swirl.Great plastic deformation occurs in both sides metals of the interface.A few of molten metal exists in bonding interface,with the feature of melting block,melting zone and a large number of metal fragments.The element line scanning analysis indicates that the main alloy elements obviously present the characteristics of gradient distribution in the bonding interface,and the diffusion phenomenon occurs among alloy elements.The tiny atomic diffusing layer is about 0.7?m.It achieves a solid metallurgical combine.After annealing treatment,the bonding interface remains as the pattern of wave combination.As the heat treatment temperature increases and the holding time extends,plastic deformation fades away,appearing isometric crystals.Meanwhile,the atomic diffusing layer also increases.However,there is no hard intermetallic compound precipitation in the bonding interface according to the results of XRD analysis.The results of dynamic potential polarization curve and electrochemical impedance spectroscopy evaluated in artificial sea water show that both of the composite plates and cladding metal present passivity.But in comparison,the corrosion resistance of cladding metal is excellent,while the corrosion resistance of composite plate decreases slightly,which is better than the corrosion resistance of as-annealed composite plates.However,the decrease extent is little,which can satisfy the requirement of corrosion resistance to practical engineering structure.According to the results of tensile shearing test,fracture happens in the base plate,the corresponding tensile shearing strength reaches 330MPa.And no crack occurs on the surface of composite plate,which explains the interface presents high bonding strength.The test results of microhardness distribution show that the highest microhardness appears in the interface of composite plate,and the microhardness becomes lower as the distance is farther away from the interface.The mean reason is the work hardening effect caused by plastic deformation.However,the microhardness decreases obviously for the as-annealed composite plate,which explains that appropriate heat treatment can eliminate the deformation hardening caused by explosive welding at a great extent. |
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