Abstract: The advantage of tube axial compressive forming and whether to realize forming process depend on whether to produce the tearing or buckling failures during the forming process. Based on minimum energy principle for plastic forming, the buckling machenism and effects of forming parameters on it are investigated by theoretical analysis and experiment, and the criterion for bucking failure is developed which can be used to determine proper parameters for stable forming. The results show that the effect parameters of buckling failure includes geometrical parameters, material properties, and friction condition. The main governing parameter that controls the success of forming process without buckling is the correct choice of die radius, and existing a maximum radius and a minimum radius, in this range no buckling failure happens. With the high value of material strain hardening exponent n and the low value of the thickness to diameter ratio, it is possible to prevent buckling failure, at the same time decreasing the friction condition is helpful to prevent buckling. The criterion for bucking failure purposed in this paper is used in tube axial compressive forming process for aluminum tube blanks with brand No 5052, d0=31.0 mm, 41.0 mm and the results show that criterion is reliable and practical.

Key words: Buckling, Mechanical model of failure, Tube axial compressive forming