• Transactions of Materials Processing
• /
• v.23 no.8
• /
• pp.489-494
• /
• 2014

Micro forming is an appropriate process to manufacture very small metal parts which can be employed in the field of electronic devices or electrically controlled mechanical systems. The purpose of the current study was to investigate the influences of both blankholding force and blank diameter for the deep drawing of very small cups. It is essential to control the blankholding force because improper force can result in defects such as wrinkles in the flange or cracks in the corner of the drawn cups. In the current study blankholding force was controlled by springs connected to the blankholder of a press die. Exchangeable bushing dies with various die-corner radii were also used. To obtain the limit drawing ratio for each working condition several sizes of circular specimens were prepared using blanking tools. Beryllium copper(C1720) alloy sheet of $50{\mu}m$ thickness was chosen for the experiments. The maximum limit drawing ratio of 2.1 was achieved experimentally for the conditions of the blankholder force(BHF)=5.3kgf and Rd=0.3mm. Both thickness and hardness along the central section of drawn cups were measured and compared for different drawing conditions. It was found that the deviation of measured data in the thickness and hardness distribution increases with increasing blankholder force and blank diameter.

• Korean Journal of Materials Research
• /
• v.3 no.1
• /
• pp.43-49
• /
• 1993

Excellent deep drawability and strain aging rsistance are obtained by the addition of alloying elements such as Ti and Nb which can form carbide and nitride easily into Al killed extra low carbon steel. Recrystallization textures and mechanical properties of the three different extra low carbon steels with B containing Nb only, Ti only, and both Nb and Ti, respectively, along with have been compared. Inverse pole figure shows that (100) and (111) texture intensities of Nb containing steel changed a lot during the annealing treatment and the degree of texture-structural change in the steel containing both Nb and Ti is about the same as that in the Ti-containing 5teel. After annealing the pole figure shows that the {Ill} < 110 > and {112} < 110> textures are the strongest in the cold rolled state and the annealed state, respectively. However, there is little difference in texture structure among the three kinds of steels. There is a tendency that the steel containing both Nb and Ti the grain size of which is the smallest is the highest in hardness. Nb-containing steel is the next and Ti -containing steel is the last in hardness.

• Korean Journal of Materials Research
• /
• v.3 no.2
• /
• pp.131-139
• /
• 1993

Abstract Alloying elements such as AI, Ti, Nb and B in the extra low carbon AI-killed steel precipitate as nitrides or carbides and change the recrystallization texture structure of the steel during heattreatment with the result of strong effects on the deep drawability of the steel sheet. In this study the effects of fine precipitates such as nitrides and carbides on the texture of extra low carbon steels into which Ti, Nb, B, P, Si and Mn were added as alloying elements were investigated by means of TEM, SEM and optical microscopic analyses. Fine N$b_2$C and T$i_2$AIN precipitates are mainly observed in the steel containing both Nb and Ti, while fine AIN and coarse BN precipitates are observed in the Nb~containing steel and coarse T${i_4}{N_3}$ and ${N_10}{N_22}$/T$i_68$ precipitates are observed in the Ti-containing steel. The grain size of the Ti containing steel is larger than that of the Nb containing steel and that of the one containing both Nb and Ti.