We wanted to share with you an important issue about our hollow bar production which we started in August 2005. Sarbak Metal A.Ş. we produce "EN 12168- Hollow Bars for Automats", Hollow Bars, Collectors and Various Profiles for chemical composition, mechanical specifications and dimensional tolerances according to European Norms. Ve San. all Hollow Bars and Profiles that are supplied from Sarbak Metal Tic. Ve San. A.Ş. As seen in the following figures, its compliance is controlled according to "TS EN ISO 196 / November 1998 - Wrought Copper and Copper Alloys - Detection of Residual Stress - Mercury (I) Nitrate Experiment". The purpose of the internal stress relieving heat treatment is, during and after the hot extrusion to eliminate the permanent internal stresses due to cold drawing. Thus, the physical life of the material is longer. If this procedure is not applied, cracks may occur in time during use and after installation. Three important factors in the formation of stress corrosion cracks are as follows; 1- Metallurgical composition, 2- The material being under stress (obvious), 3- The existence of a special corrosion trigger in the material; Impurity, high-temperature cold forming, etc. It does not matter if the tension is internal or external. However, pressure stresses do not create stress corrosion. Stress corrosion cracking occurs suddenly and without any sign. Stress corrosion cracking occurs by being affected by ammonia environment in brass. Atmosphere, water vapor etc. For prevention there must be 1- Heat treatment (the safest way) 2- Ammonia-free environment. 3- Precaution should be taken during construction and installation. Attention should be paid to the construction and installation in order to obtain the optimum voltage distribution with proper calculation. As a result of the test, you can see in the pictures that the material on whose internal stress detensioning was applied did not crack; the material on whose internal stress detensioning was not applied did crack.