Experimental and Numerical Study on the Explosive Welding of Niobium-Steel

The aim of this work is to study the use of explosive welding to produce Niobium-Steel composite plate, which is used in nuclear industry equipment material manufacturing. The welding parameters was determined by weldability window and numerical simulation was used to predict the wave shape of the welding interface. The morphology of the interface wave was observed by scanning electron microscope. Component measurement around interface waves. The experimental samples were investigeted using mechanical tests. The results show that the explosion parameters optimized by theory and numerical simulation can be used to obtain a niobium-steel composite plate with better welding quality. It can be proved that the welding quality is better by observing the interface wave and testing the mechanical properties, it can be seen that the melting zone of the welding interface is composed of niobium and steel by the composition analysis instrument. The morphology of the welding interface wave is consistent with the numerical simulation results, and the numerical simulation shows the changes of temperature, strain, and stress during the welding process.

Characterization of the Microstructure and Bonding Properties of Zirconium-Carbon Steel Clad Materials by Explosive Welding

An investigation was carried out to characterize the microstructure and bonding properties of the zirconium-carbon steel explosive clad. The microstructure and the composition of the clad were characterized using optical microscopy and scanning electron microscopy. Bonding properties were inspected by using bending and shearing tests. The examination results indicate that the R60702 and Cr70 plates were joined successfully without visible defects. The interface wave is symmetrical. There is no element diffusion across the interface of the clad plate. There are melt blocks at the interface. Bending and shearing test results indicate that the bonding properties of the clad meet the requirements of the ASTM B898 specification. And after shell rolling, no delamination appeared at the interface. Thus, it indicates that the clad plates have good bonding quality and meet the processing requirement.

Ultrasonic Interface Wave for Interlaminar Crack Detection in Steel–Titanium Composite Pipe

The bimetal composite pipe has found wide ranging applications in engineering owing to its excellent mechanical and physical performances. However, the interlaminar cracks which are usually invisible and inaccessible may occur in the bimetal composite pipe and are difficult to detect. The ultrasonic interface wave, which propagates along the interface with high displacement amplitudes and low dispersion at high frequencies, provides a promising nondestructive testing (NDT) method for detecting cracks in the bimetal composite pipe. In this study, the interlaminar crack detection method in the steel–titanium composite pipe is investigated analytically and experimentally by using interface wave. The interface wave mode in steel–titanium composite pipe is first identified and presented by theoretical analyses of dispersion curves and wave structures. The selection of suitable excitation frequency range for NDT is discussed as well. Then an experiment is conducted to measure the interface wave velocities, which are in good agreement with the corresponding numerical results. In addition, interlaminar cracks with different locations in steel–titanium composite pipe are effectively detected and located, both in the axial and circumferential directions. Finally, the relationship between the reflection coefficient and the crack depth is experimentally studied to predict the reflection behavior of interface wave with crack. The numerical and experimental results show the interface wave is sensitive to interfacial crack and has great potentials for nondestructive evaluation in the bimetal composite pipe.

Analysis on the Synthetic Seismograms of Seismic Wave Caused by Low Frequency Sound Source in Shallow Sea with Porous Seabed

Elastic wave in the seabed caused by low frequency noise radiated from ship is called ship seismic wave and can be used to identify ship target. In order to obtain the propagation features of ship seismic wave in shallow sea with thick sediment, this paper introduces an algorithm for synthetic seismogram aroused by low frequency point sound source in shallow sea based on Biot’s wave theory for saturated porous media. Numerical calculation of synthetic seismogram at seafloor was carried out at a typical shallow sea environment with thick sediment. According to the results of numerical examples, the time series of seismic wave at seafloor is mostly composed of interface wave and leaky modes. The interface wave can propagate to far distance with small attenuation when the source frequency is very low. When the source frequency increases, the interface wave can no longer propagate to far distance like the leaky modes because the attenuation of sediment increases rapidly with frequency. The porosity and permeability of sediment in shallow sea have some influence on the dispersion characteristic of seismic wave at seafloor.