Understanding spring back for the arched tubes constitutes a major problem for every tube manufacturer. Even when the allowable fluctuations are limited to tenth of degrees, angular fluctuations of several degrees are usually observed. This indicates the importance of the problem. The aim of this study is to understand the role of materials in determining spring back characteristics of bent tubes. The first stage of the work thus consists in finding analytical, semi-analytical, numerical or even empirical models in order to formulate the spring back. These models are then validated by experimental tests. In second stage, an analysis of sensitivity is carried out in order to determine the influence of various parameters like the geometry, the process or material.