Izumi Fukuda

Effect of Shot Peening on Bending Strength of AZ31 Magnesium Alloy Pipe

This paper deals with effect of shot peening on bending strength of cylindrical pipe of AZ31(Mg-3%Al-1%Zn) magnesium alloy. Specimen shape of the pipe is 240mm in gauge length and 330mm in total length, 22mm and 18mm in outer and inner diameters. Shot peening treatments were given on the surface of the pipe using an impeller-type peening machine and/or an air-type peening machine. Tensile and compressive tests were carried out under axial load at a crosshead speed of 10mm/min. Bending strength test was also performed at a crosshead speed of 100mm/min under lateral load using an Instron-type testing machine. From the experimental result, the bending yield load of the pipe was strengthened after shot peening treatment. It was found that the compressive yield stresses of the shot-peened pipe were strongly related to their bending strengths.

Effect of Temperature on Plastic Buckling Strength of Shot Peened Pipe of Magnesium Alloys

This paper deals with the effect of temperature on plastic buckling strength of cylindrical pipe of some magnesium alloys subjected to shot peening process. Workpieces are three cylindrical pipes of AZ31, AZ61 and AZ80 magnesium alloys. The shape of pipe is 30mm in height, 16mm and 14mm in outer and inner diameters. The shot peening treatment was given on the surface of cylindrical pipe using an air-type peening machine. Plastic buckling strength test was performed under axial compression in a case of both ends with fixed condition, at several temperatures between 293K and 573K and at a crosshead speed of 1 mm/min using an Instron-type testing machine. From the experimental result, buckling stresses for all kinds of AZ31, AZ61 and AZ80 alloy pipe were strengthened after the shot peening treatment, but a few of differences for the increasing ratio. The buckling stress of the shot-peened pipe was kept higher than that of as received one up to the test temperature of 473K, however it tended to be around equal at 573K.

Mechanical properties of a low carbon steel shock loaded by an explosive.

焼きなました低炭素鋼に水中で爆薬による衝撃圧力psを与えたのちの応力-ひずみ挙動と延性-ぜい性遷移温度Tcを調べた.降伏応力σsはpsの増大とともに減少しps=1400MPaで最小(焼きなまし材のσsの62%)になった.時効特性からこの軟化は自由転移の形成によると考えられた.p>1400MPaではσsの減少量は少なくなるが,それは双晶の増加による.1400MPa衝撃圧力負荷材のTcは焼きなまし材より15K低く,σsの単位現象当りのTcの低下は0.21K/MPaであった.