Cheng Yun Peng

Phase Selection in Undercooled Cu85Cr15 Composites

Phase selection of undercooled Cu85Cr15 composites was analyzed by using different solidification conditions. The results revealed that the arc melted composites generally have non-uniform Cr-rich dendrites distributes on Cu-rich matrix. Due to strong electromagnetic stirring, uniform Cr-rich dendrites distributes on Cu-rich matrix for electromagnetic levitation melted composites. Both fine Cr-rich dendrites and Cr-rich particles coexisted in Cu-rich matrix for splat quenched composites, which means liquid phase separation occurred for the high cooling rate.

Study and Practice of Bilingual Teaching Course in Major of Materials Forming and Control Engineering

According to the require of national characteristic specialized construction education for the students and combinating the practice of bilingual teaching in major of materials forming and control engineering, this paper studied the modularization bilingual teaching reform in the curriculum teaching process in the local colleges or universities. The significance of bilingual teaching in major of materials forming and control engineering is clarified. The multimedia bilingual teaching is carried out in the course of foundation of materials forming and technology. The results prove that it is practical and fruitful to conduct bilingual teaching based on excellent original english teaching materials, multimedia methods, scientific organization and modularization teaching.

Research on Algorithm of Forming Limit Height in Semi-Ball Bottom Cylindrical Deep Drawing

With physical experiments and numerical simulation about semi-ball bottom cylindrical parts and flat-bottomed cylindrical parts, we got the thinning law about spherical bottom of semi-ball bottom cylindrical parts, and got forming limit height difference of semi-ball bottom cylindrical parts and flat-bottomed cylindrical parts under the same conditions. In accordance with the principle of constant volume, the cylindrical ball height of semi-ball bottom cylindrical parts can be converted to draw from the cylindrical part height of the flat-bottomed cylindrical parts, which introduced a method of calculating the forming limit height of semi-ball bottom cylindrical parts. Through practical examples, this algorithm is feasible.

Effect of Die Radius and BHF on Formability of the Corner of Box-Shaped Parts in Deep Drawing Processes

Formability of the corner in the deep drawing of box-shaped parts was studied. The forming of box-shaped parts was simulated through numerical simulation software DYNAFORM from the different die radius size of shoulders and corners, the different BHF of straight and curved edges and different materials, etc.. The results shows that, the forming limit height of box-shaped parts increases with the larger the die radius of shoulders and corners, and forming limit height of SS304 in the materials studied is the highest, because it has larger yield strength; If the BHF of straight and curved edges has the constant size, the forming limit height of box-shaped parts will be lower when the BHF increases, while forming limit has a clear upward trend as blank holder force increases in the deep drawing processes which accords with the change law of resistance during the dislocation movement.

Effect of Cooling Rate on the Microstructure of Cu80Cr20 Alloys

The effect of cooling rate on the microstructure of Cu80Cr20 alloys was studied by using vacuum non-consumable arc melting, vacuum induction melting, electromagnetic levitation and splat quenching. The microstructure evolution of the Cr-rich were analyzed by scanning electron microscopy (SEM) and optical microscopy. The results showed that nonuniform Cr-rich dendrite distributes on Cu-rich matrix for arc melted alloys and uniform Cr-rich dendrite distributes on Cu-rich matrix for electromagnetic levitation melted alloys and vacuum induction melted alloys. However, the Cr-rich phase show both dendrites and spheroids for splat quenched alloys. This means liquid phase separation occurred during rapid solidification.

Microstructure of Cu75Cr25 Alloys under Different Conditions

The microstructure of Cu75Cr25 alloys was investigated by using vacuum non-consumable arc melting, electromagnetic levitation and splat quenching. The microstructure and solidification behavior of the Cr-rich were investigated by scanning electron microscopy (SEM). The results showed that inhomogeneous Cr-rich dendrite distributes on Cu-rich matrix for arc melted alloys. The microstructure consisting of a fine dispersion of Cr-rich dendrite in a Cu-rich matrix for electromagnetic levitated alloys. However, the morphology and size of the Cr-rich phase vary greatly with the cooling rate for splat quenched alloys. The Cr-rich phase show both dendrites and spheroids, this means liquid phase separation occurred during rapid solidification.

Microstructure Study of Undercooled Hypereutectic Cu95Cr5 Alloys

Microstructure of Cr-rich phase in undercooled hypereutectic Cu95Cr5 alloys was studied by using arc melting, electromagntic levitation melting and splat quenching. The results showed that the alloys generally have a microstructure consisting of a fine Cr-rich dendrites in a Cu-rich matrix. Even there existed strong electromagnetic stirring during solidification process, the nonhomogeneous Cr-rich dendrites were observed in electromagnetic levitation melted alloys. However, fine homogenous primary Cr-rich particles or equiaxed Cr-rich grains distributed in the Cu-rich matrix in splat quenched alloys.

Analysis of Numerical Simulation and Experimental of the Flange in the Deep Drawing of Box-Shaped Parts

Deformation of the flange in the deep drawing of box-shaped parts was studied. The forming of box-shaped parts was simulated through numerical simulation software DYNAFORM, and hardness of box-shaped parts was measured with a hardness tester. The results shows that, the sheet thickness near the midpoint of straight edge is more lager than near the corner, and flow stress is small, indicating that plastic deformation is not sufficient. Sheet thickness of box-shaped parts of large aspect ratio is relatively large, and sheet flow is difficult, which is not conducive to forming. In the experiment, the hardness of rounded corner part is significantly greater than two adjacent straight edges at the same height, which shows that material flow of the rounded corner part is good and hardening phenomenon is obvious, and the maximum hardness is near the entrance to the die corner. The flange deformation of box-shaped parts of the experimental and numerical simulation is the same.

Analysis of Numerical Simulation in the Deep Drawing of Box-Shaped Parts Using Variable Blank Holder Force

Blank holder force of box deep drawing is studied changes with time and displacement by DYNAFORM numerical simulation software. The results shows that, when the straight edge part of the blank holder force is constant, rounded part adopts small blank holder force can significantly improve the forming limit of box deep drawing, but the wrinkle is still evident. If the straight edge and rounded part of the blank holder force changes with time, not only deep drawing limit increase, wrinkles are also significantly reduced, indicating that the forming limit of the box shaped part is more effective on the blank holder force changes over time than with the position variation.

Behavior of Cr-Rich Phase during Rapid Solidification Cu71Cr29 Alloys

Behavior of Cr-rich phase in rapid solidification Cu71Cr29 alloys was investigated by using melt spinning and splat quenching. The microstructure and solidification behavior of the Cr-rich were investigated by scanning electron microscopy (SEM). The results showed that the alloys generally have a microstructure consisting of a fine dispersion of a Cr-rich phase in a Cu-rich matrix. However, the morphology and size of the Cr-rich phase vary greatly with the cooling rate. On the one hand, the average size of the Cr-rich phase is reduced with increasing cooling rate. On the other hand, the Cr-rich phase show both dendrites and spheroids for lower cooling rate but only spheroids for the higher cooling rate. This means liquid phase separation occurred during rapid solidification. The results were discussed with respect to the formation of the Cr-rich spheroids during rapid solidification.