The effect of Ti microalloying on the precipitation of NbC particles in Nb-microalloyed and Nb-Ti-microalloyed steels was investigated by scanning transmission electron microscopy. The experimental results illustrate that NbC precipitates tend to be formed via a conventional “nucleation and growth” mechanism in Ti-free steel, while the particles would be precipitated as a complex form of TiN cuboid core and NbC hemispherical cap in Ti-Nb-microalloyed steel with 0.009 wt.% Ti and 0.0046 wt.% N. Ti microalloying contributed to the refinement of the precipitate size, and an enhancement of the volume fraction of NbC particles was also found based on the experimental observations.

Effect of primary austenite grain size and processing parameters on the critical strain of dynamic recrystallization (DRX) during finishing has been investigated and modeled in the present paper. The stress-strain curves were achieved based on the hot compression experiments in the condition of different temperatures and strain rates with different primary austenite grain size. The deformation temperature and strain rate were normalized as Zener–Hollomon (Z) parameter. The experimental results illustrated that the critical strain for DRX was significantly influenced by the primary austenite grain size but peak strain was not, which has been interpreted based on the nucleation and growth of DRX grains. The modeling parameters have been established based on Sellars’ model, with which the effect of grain size and processing parameters on the critical strain for austenite DRX could be quantitatively calculated, which is helpful to design rolling schedule for promote DRX in order to refine grain size. A seven-passes rolling schedule was designed in the case of only 1.5 reduction ratio. The experimental results confirmed that the grain size was significantly refined by promoting austenite DRX, which are good agreement with modeling calculation.

This essay analyses the experiment of xylene, ethyl acetate and acetone as solvent materials influencing the surface resistivity and electromagnetic shielding effectiveness of conductive filler composite material, as well as the main reasons for this difference from the perspective of material properties of the solvent. Analysis shows that, when the acrylic is the resin-based material, all three solutions can be used as a solvent to adjust the viscosity of the coating electromagnetic shielding. However, there is a huge difference in shielding effectiveness after spraying. This essay found that the dielectric constant has an important influence on the shielding effectiveness. While acetone is the solvent with the largest dielectric constant, the electromagnetic shielding effectiveness is worst. While xylene is a solvent, the electromagnetic shielding effectiveness is the best, and the volume fraction variation does not affect the electromagnetic shielding effectiveness. While ethyl acetate is a solvent, the influence is more complicated. There is need for a comprehensive analysis on the mobility and film-forming properties.