A comparation of 304 stainless steels and galvanized sheets formability in different properties

Stainless steel and galvanized sheets have a wide usage in many industries. The main reason of this preference, particularly in white goods and automotive industries, is providing a nearly optimum combination of strength, formability and surface quality. The scrapping caused by the breaking or the localized necking of the sheet during the forming process affects the continuity, economy and quality of the production in a negative way.Both chemical composition and processes in the production cause some differences in metallurgical and mechanical properties between the quality grades of sheet products. These differences significantly affect the formability under press and the product quality.The most of stainless steel and galvanized sheets are hardened by the cold forming which provides increase in strength. In this way, the thickness of the goods can be decreased and considerable saving in the total weight and cost can be obtained.In this study, the general properties of stainless steel and galvanized sheets and its classification according to several standards were studied first. In addition to this, principles of several sheet metal forming methods were mentioned. To understand the act of the properties of sheet metal in the forming operations and to determine the formability of material, some metallurgical and mechanical concepts, constituting the base of formability theories were studied. Some mechanical test methods to evaluate formability of sheet metal were studied and the affects of mechanical properties to steel sheet formability were explained.In the last part, the mechanical properties and their changes with strain rate were determined by tensile tests in different angles to the rolling direction for 304 stainless steel and DX51 galvanized sheets. The differences in cupping values and maximum cupping forces were determined by Erichsen cupping tests, carried out in dry and lubricated conditions under different testing speed. The changes in the limiting draw ratio and maximum drawing forces were determined by deep drawing tests in similar conditions.