It is well known that sheet forming of magnesium alloys is inferior in comparison with other metal sheets. In this research, in order to examine bending, stretching, formability and drawability of AZ31 magnesium alloy sheets, the effects of rolling conditions of the sheet were investigated by the model experiments. The hot rolled sheet with reduction of 1 pass 30~50% at the high temperature showed good value. Furthermore, various properties were improved by final annealing temperature of the alloy sheet. In the bending test, the ratio of radius (R) to thickness (t) for the rolled sheet showed the value of 2 in final annealed temperature at 573–673K. In the stretching test, the best biaxial deformation limit was obtained in the 50% hot rolled sheet after annealed at 623 K. In the drawing test, the sheet of LDR showed the value of 1.7 in the 30% and 50% hot rolled sheets after annealed at 573 K. These results implied that good formability of AZ31 magnesium alloy sheet was obtained by selecting proper rolling conditions.

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In this study, we tried to solder directly heat treatable aluminum alloy to oxygen free copper without metallizing of solder, and investigated the effects of flux and the application of ultrasonic vibration on the strength of soldered joints and the soldered layer structure. The following results were obtained. Aluminum can be soldered to copper by applying ultrasonic vibration and using flux. However, in this case, many voids of 30~35 volume % are formed in the soldered layer. At the interface between Cu and soldered layer, AlCu intermetallic compound phase is formed and it grows with the duration of the ultrasonic vibration. When the thickness of the intermetallic phase is over about 760nm, the strength of the joint decreases. Only by applying ultrasonic vibration aluminum can be also soldered to copper without flux. The soldered layer includes few voids, however, the strength of the joint is lower than that of the joint soldered using flux. In this case, the AlCu intermetallic compound phase is also formed at the interface between Cu and soldered layer, and it grows with the duration of the ultrasonic vibration. However, the intermetallic phase does not grow uniformly and continuously along the overall interface, resulting in the low strength of the joint.

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The effects of frictional wear characteristics on fretting fatigue strength of Ti–4.5Al–3V–2Mo–2Fe conducted with various annealing treatments were investigated in this study. The weight loss tends to increase with decreasing the hardness. The estimated weight loss of the slip region at high cycle fretting fatigue life region tends to increase with increasing the length of the slip region. The fretting fatigue life tends to decrease with increasing the length of the slip region and increasing die estimated weight loss of the slip region. The depth of the crack growth zone caused by the contact pressure at high cycle fretting fatigue life region tends to increase with increasing the estimated weight loss of the slip region. The fretting fatigue life tends to decrease with increasing the estimated weight loss of die slip region and increasing the depth of the crack growth zone caused by the contact pressure.

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The sintering rate of the final stage in HIP process of imperfectly sintered Ti–6Al–4V and Ti–13V–11Cr–3Al alloy has been investigated on the basis of power-law creep. Activation energy and stress exponent of HIP-sintering rates of titanium alloy have the values close to the previously reported ones of creep and high temperature deformation. On the other hand, using the finite element method, it was evaluated that the f(D) function reported by P.L.Wilkinson et al. and J. M. Duva et al. etc. is most suitable as long as based on the cell model. A'_hs could be determined using this f(D) function. In addition, it was concluded that the equation of the HIP-sintering rate should be corrected by consid-ering the trapped gas in the pore, when the initial relative density at HIP is lower than 0.97.

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