An electrical circuit was developed to model the behaviour of gas metal arc welding. The model incorporates results from a one-dimensional free burning arc model to describe the arc and a second order differential equation to describe one-dimensional energy conservation in the welding anode. Commercial circuit analy sis software was used to solve the circuit model. Predictions have been compared with experimental data for short circuit transfer mode as well as spray. Predictions agree well with experimental results. The model provides a fast and useful technique to simulate the gas metal arc welding process. In short circuit transfer mode, the model predicts that chaotic phenomena are occurring.
Using a fiber laser welding head, crack-free WC-Co/Steel weld depositions are obtained with optimized welding parameters. The microstructure, composition, phase, structure, and bend strength are analyzed using optical metallography, scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and bend test. The influence of the microstructure and WC/matrix interfaces in the vicinity of joint failure at the cemented carbide side is discussed. It is evident that the deposit consists of austenite dendrites and interdendritic eutectic carbides. The austenite further transforms to martensite on-cooling. The flexural bend strength and yield strength of the joints attained 970 MPa and 876 MPa, respectively. Bend fracture occurs at the HAZ in the cemented carbide side of the joint, characterized with cleavage fracture and quasi-cleavage fracture. TEM and HRTEM image of WC/Co interfaces verified the W2C and eta phase formation in the HAZ that contributed to the embrittlement.
In order to study the attenuation of shock waves induced by a high-power pulsed laser in magnesium alloy, an AZ31B magnesium alloy sample is processed with an Nd:Glass laser with a wavelength of 1054 nm and pulse width of 23 ns, and the relative pressures of the shock waves are measured on time by a polyvinglidene fluoride (PVDF) gauge with a short rise time and a wide linear response range, combined together with an oscilloscope. The law of attenuation of laser shock wave is obtained by measuring the intensity pressures on the rear surface of the target for different thicknesses through which the shock waves pass each time. The experimental results show that the average velocity of the shock wave attenuation in magnesium alloy is 5.83×103 m/s with using a laser pulsed energy of 5 J is in good agreement with the propagation velocity of stress longitudinal wave; the law of the shock wave attenuation is exponential. The experimental result can be very useful for the laser shock processing on magnesium alloy.
A nanocrystallines surface layer was produced in Fe3Al intermetallic compound by surface mechanical attrition treatment (SMAT). The microstructure of deformed layer, phase structure and morphology of surface nanocrystallines were characterized through optical microscopy, X-ray diffractometry, transmission electronic microscopy and high resolution electronic microscopy. The results show that a deformed layer about 11μm wide is produced after 10min surface mechanical attrition. The grains on the top surface of Fe3Al are refined to nanocrystallines and the grain size of nanocrystallines is about 35nm. High density dislocations collect on the boundaries of grains. The formation of nanocrystallines is controlled by grain subdivision mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.