The defects of the lower tooth height and of larger pitch in thread portion of rolled pieces are prone to appearing when rolling thread shaft in cross wedge rolling. To solve this problem, changing the blank shape and size were tried. Two types of concave conical and round blanks are designed with concave conical blanks obtained by rolling in the cross wedge rolling. Because the design of the rolling die is simple, good precision of blank can be ensured. Multiple size types of blanks were designed and the rolling experiment was made in the rolling mill of model H630. By measuring the values of the tooth height and pitch, the effect of blank shape on thread shafts rolled in the wedge rolling were investigated carefully. The reasonable size range of the blank shape was obtained. The conclusions above pave the theoretical foundation for the in-depth study on this technology.

The study on forming helical tooth shaft processes in cross wedge rolling can contribute to the advantages of material-saving and efficient. Die tooth profile is an important process parameter of cross wedge rolling helical tooth shaft. Three kinds of forming process of die helical teeth were simulated by DEFORM-3D finite element analysis software to analyze three different die helical tooth. According to the tooth forming characteristics, the effects of three kinds of die tooth profile on forming of a polled piece were analyzed. When rolling a polled piece using the die with the same addendum width, it is convenient for die processing and the effect of polled piece forming is better; when using the die with the narrow front and gradually wider rear, the defects of uneven tooth bottom and larger pitch may happen. The rolling experiment was made by using the die with the same width at the tooth bottom. The results are in good agreement with the simulation. Therefore, we should use the die with unchanged addendum width, tooth height and the sidewall proportional increased when designing the die.

The typical Fe-25Mn-3Si-3Al TWIP steel with different microstructure scale were investigated. It was found When the grains size is up to 35μm in the 25Mn-3Si-3Al TWIP steel samples, the twinning induced plasticity (TWIP) effect can fully developed and results in above 80% elongation. grain size had a strong effect on the mechanical properties. It was concluded that with increasing grain size ultimate tensile strength decreases, while elongation increases obviously.The annealing twin has the twin’s orientation, during deformation the annealing twin has get orientation ready for deformation twins

The traditional forming technologies of stainless steel tapered tube have some disadvantages, such as its complicated processes, few product specification, low production efficiency and high production cost. Dieless drawing is a new kind of near net-shaping process for fabricating tapered metallic tubes with large deformation per pass, high yield ratio of material and flexible production. Dieless drawing of stainless steel tapered tube was studied systematically in order to establish both temperature field model with respect to the changes of boundary condition and metal flow velocity during deformation, and a drawing speed controlling model with respect to the volume change of deformation zone. The models were verified by experiments in the present investigation. Finally, a continuous pickling process with variable-speed was proposed for tapered metallic tube, which was successfully applied to surface oxidation film removal of the stainless steel tapered tube.