Intermediary Thermic Treatments Applied to The Bz Be2 Tubes Plastic Deformation

This paper proposes to treat some theoretical and experimental aspects of plastic deformation and thermal treatments applied to an alloy between bronze and beryllium.

1.Generalities:

For obtaining the tubular products there has been used a foil from an alloy between bronze and beryllium 2% (BzBe2) and the thickness of h=0.5 mm, according DIN 1718.

Because the thickness of the foil is smaller than 1 mm (h < 1mm), there has been applied the plastic deformation without modifying the thickness of the material. The report “ H/d” ( H – highness, d – diameter ) being ample there has been resulted five successive plastic deformation.

The deep plastic deformation supposes the modification of the shape and of the dimensions of the foil under the action of an exterior force applied to inferior temperatures of the re-crystallization temperature.

During the technological procedure of deep plastic deformation the material passes through a structural and physical mechanical non equilibrium state named cold hardening.

For reintroduction to the equilibrium state, for continuing the plastic deformation operation there are necessary intermediary thermic treatments of re-maturation of re-crystallization.

2. The deep plastic deformation of the ze2 tubes without modifying the thickness

The calculus of the slab billet diameter “ Dsemifabricat” used for deep plastic deformation :

The calculus of the plastic deformation diameters basing on the plastic deformation coefficients “m” :

from the execution draw

H = 140 mm

d = 14 mm

h = 0,5 mm

It results that the given dimensions tube can be obtained through five successive plastic deformations. Because the plastic deformation coefficients are big, the technological operation will be executed until the permissibility limit.

Fig. 1 Execution draw of the BzBe2 tube

The calculus of the plastic deformation height “H” :

The obtained data are presented centralized in table 1: