Papers by Author: Zeng Pan

Abstract: Butt laser welding experiments of Q235 sheets in different parameter conditions are conducted, and residual deformation values of the samples are measured. To predict welding deformation, heat transfer analysis is first done by FEM to obtain corresponding quasi-steady temperature data; then an equivalent model is constructed based on temperature and inherent strain theory, and bending moment values are reversely calculated through specific measured deformation values by static analysis, which are verified by a series of process experiments. In the end, the established equivalent model is applied to predict welding angular deformation of the I-beam structure. It is shown that the proposed method has a high accuracy and efficiency.

Abstract: Thixo-forming is in the forefront of metal processing technology in the 21st century. The research on thixo-co-extrusion of multi-layer tube as extension and development of the semi-solid forming technology is a completely new processing method for the composite material forming and is of great significance, in which different semi-solid billets (slurries) are extruded at the same time to form multi-layer tubes. In this study, different sizes of column-shaped and ring-shaped billets of Al/Mg alloys were firstly prepared by using specially designed molds. Then they were reheated by electric-resistance furnace，microstructures from different heating laws were investigated. Lastly, FEM simulation on thixo-co-extrusion of double-layer tube with A356/AZ91 was conducted.

Abstract: The perfect semi-solid magnesium alloy had been prepared using ultrasonic stirring method. The effect of technological parameters such as melt temperature, ultrasonic power and ultrasonic treatment time on the microstructure of semi-solid AZ61 alloy had been investigated. The results showed that the better refined and well-distributed globular semi-solid magnesium alloy had been acquired with the increasing of output power of ultrasonic stirring when melt temperature and ultrasonic treatment time were at a certain range.

Abstract: Welding is a main processing way in the manufacture of steel bridges. Welding deformation is one of the main influencing factors on the quality of steel bridges, which relates to the effect of material mechanical behavior and welding techniques. The welding distortion is considered to be a result from the inherent strain after welding, which dependent on the highest temperature reached and the constraint at each point. 16Mnq is a common structural steel used in railway steel bridges. Thus, the paper addresses the high-temperature mechanical behavior of 16Mnq through a series of experiments under various peak temperatures and constant constraint conditions. Relationships between temperature, constraint and strain at high temperatures were discussed. The yielding phenomenon based on high temperature occurs under a certain condition of both constraint and temperature, and this phenomenon had significant influence on the inherent strain. The results are significant to understand thermal-mechanical behavior of material and to predict the inherent strain under constant constraint conditions during heat circulates of welding.