Nanchang Hangkong University

About: Nanchang Hangkong University is a education organization based out in Nanchang, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 7004 authors who have published 5270 publications receiving 62162 citations. The organization is also known as: Nanchang Aviation University.

Superplastic deformation mechanism and mechanical behavior of a laser-welded Ti–6Al–4V alloy joint

Abstract: The mechanical behavior and superplastic deformation mechanism of a laser-welded Ti–6Al–4V alloy joint were investigated. Uniaxial tensile tests were performed on welded specimens at 870–920 °C temperature and 10 −3 to 10 −1 s −1 strain rate. The microstructural evolution of the weld zone was observed under the strains of 43%, 143%, 229%, and 387%. The laser-welded joint was found to have good superplasticity under a suitable strain rate; the highest joint elongation reached 397%. Superplastic deformation in the weld zone accompanied the globularization of the as-welded microstructure. Continuous globularization ensured a good superplasticity of the laser-welded joint. As a major cause of the globularization of lamellar structures in the weld zone, the stress activated the diffusion of Al atoms by changing the chemical potential at the boundaries of the α phase. Consequently, α → β phase transformation occurred. The globularization of the as-weld microstructures was considered to be governed by this transformation and the development of grain boundary sliding.

Studies on influences of initial magnetization state on metal magnetic memory signal

Abstract: Metal magnetic memory testing is a novel testing method which can early test stress concentration level of ferromagnetic components. In theory, the influences of the initial magnetization on the magnetic memory signal were studied. In the experimental aspect, take Q235 steel specimen for example, the relationship between initial magnetization state and metal magnetic memory signal was researched by static tensile test under three different initial magnetization conditions. Both the experimental studies and theoretical analysis come to similar conclusion that the variation trend of magnetization with the stress is that the initial magnetization status tends to shift towards the non-hysteresis magnetization state. With the increasing of stress, the magnetizing state gradually shifts towards the anhysteretic magnetization state, and the variation rate is directly proportional to the difference between the initial magnetization and the non-hysteresis magnetization. Our study indicates that the initial magnetization state has an important influence on the magnetic memory signal, and the research results can provide reference for quantitative test of metal magnetic memory testing technology.